Triaxial compaction provides improved green density and strength over other compaction methods like unidirectional pressing and isostatic pressing. Applying both axial pressure and confining pressure during triaxial compaction allows independent control of stresses and improves density uniformity. Higher confining pressures and shear stresses lead to higher green densities and strengths for powder compacts.
Powder metallurgy is a process that involves producing metal powders and compacting and sintering them to form finished parts. It allows for complex alloy compositions and near-net shape manufacturing, avoiding costly machining. The key steps are powder production, blending/mixing, compaction into a green compact, sintering to bond particles, and optional finishing. It offers advantages over casting and machining for net shape precision parts in large volumes.
The document discusses the powder metallurgy process which consists of three main steps: 1) blending and mixing of metal powders and additives, 2) compaction of the blended powder using pressure-based or pressureless techniques, and 3) sintering the compacted powder below the melting point to bond the particles together without melting. Optional secondary operations such as heat treatment, machining or infiltration can further process the sintered parts.
The fabrication methodology of a composite part depends mainly on three factors:
(i) the characteristics of matrices and reinforcements,
(ii) the shapes, sizes and engineering details of products, and
(iii) end uses.
The composite products are too many and cover a very wide domain of applications ranging from an engine valve to an aircraft wing.
The fabrication technique varies from one product to the other.
Hot isostatic pressing (HIP) is a powder metallurgy technique that uses high temperatures and pressures to densify metals and ceramics. HIP reduces porosity and increases density and mechanical properties. An inert gas applies uniform isostatic pressure at temperatures up to 2000°C to consolidate materials into fully or near fully dense components for applications like ball bearings, body armor, and dental implants.
Hot pressing is a technique that combines powder compaction and sintering into a single step. Powder is placed in a graphite die and sintered under pressure and heat. This allows densification of materials that otherwise have poor sintering behavior. The process involves placing powder in a die and applying heat and pressure simultaneously. The temperature increases during compaction to allow sintering through mechanisms like plastic deformation and diffusion. Hot pressing produces fully dense materials in less time compared to conventional sintering. It finds applications in advanced ceramics and dispersion strengthened metals.
This document discusses metal forming processes. It defines forming and shaping, and provides examples of each. Metal forming involves plastic deformation of material under large external forces to change its shape. The document classifies metal forming processes as cold working, hot working, or warm working based on the temperature of the material. It also discusses properties important for metal forming like ductility and strength. Rolling, forging, extrusion, drawing, and press working are provided as examples of metal forming processes.
Cold isostatic pressing (CIP) is a technique where high pressure is applied uniformly to metal powder sealed in a flexible container. This compacts the powder to a density of 75-85% without die wall friction, resulting in a part with uniform density and no residual stresses. There are two methods - the wet bag process suited for batch production of complex parts, and the dry bag process using a fixed mold for mass production. CIP is used to make intricate or long shapes out of materials like titanium, tool steels, tungsten, and molybdenum powders.
This document provides an overview of powder metallurgy, including:
1) The topics that will be covered related to powder metallurgy processes and properties including powder manufacturing, sintering, and applications.
2) The basic steps in powder metallurgy including mixing powders, compacting, and sintering to produce parts from metal powders.
3) The advantages of powder metallurgy which include a wide range of possible alloys and properties, close control over dimensions, and high material utilization.
Powder metallurgy is a process that involves producing metal powders and compacting and sintering them to form finished parts. It allows for complex alloy compositions and near-net shape manufacturing, avoiding costly machining. The key steps are powder production, blending/mixing, compaction into a green compact, sintering to bond particles, and optional finishing. It offers advantages over casting and machining for net shape precision parts in large volumes.
The document discusses the powder metallurgy process which consists of three main steps: 1) blending and mixing of metal powders and additives, 2) compaction of the blended powder using pressure-based or pressureless techniques, and 3) sintering the compacted powder below the melting point to bond the particles together without melting. Optional secondary operations such as heat treatment, machining or infiltration can further process the sintered parts.
The fabrication methodology of a composite part depends mainly on three factors:
(i) the characteristics of matrices and reinforcements,
(ii) the shapes, sizes and engineering details of products, and
(iii) end uses.
The composite products are too many and cover a very wide domain of applications ranging from an engine valve to an aircraft wing.
The fabrication technique varies from one product to the other.
Hot isostatic pressing (HIP) is a powder metallurgy technique that uses high temperatures and pressures to densify metals and ceramics. HIP reduces porosity and increases density and mechanical properties. An inert gas applies uniform isostatic pressure at temperatures up to 2000°C to consolidate materials into fully or near fully dense components for applications like ball bearings, body armor, and dental implants.
Hot pressing is a technique that combines powder compaction and sintering into a single step. Powder is placed in a graphite die and sintered under pressure and heat. This allows densification of materials that otherwise have poor sintering behavior. The process involves placing powder in a die and applying heat and pressure simultaneously. The temperature increases during compaction to allow sintering through mechanisms like plastic deformation and diffusion. Hot pressing produces fully dense materials in less time compared to conventional sintering. It finds applications in advanced ceramics and dispersion strengthened metals.
This document discusses metal forming processes. It defines forming and shaping, and provides examples of each. Metal forming involves plastic deformation of material under large external forces to change its shape. The document classifies metal forming processes as cold working, hot working, or warm working based on the temperature of the material. It also discusses properties important for metal forming like ductility and strength. Rolling, forging, extrusion, drawing, and press working are provided as examples of metal forming processes.
Cold isostatic pressing (CIP) is a technique where high pressure is applied uniformly to metal powder sealed in a flexible container. This compacts the powder to a density of 75-85% without die wall friction, resulting in a part with uniform density and no residual stresses. There are two methods - the wet bag process suited for batch production of complex parts, and the dry bag process using a fixed mold for mass production. CIP is used to make intricate or long shapes out of materials like titanium, tool steels, tungsten, and molybdenum powders.
This document provides an overview of powder metallurgy, including:
1) The topics that will be covered related to powder metallurgy processes and properties including powder manufacturing, sintering, and applications.
2) The basic steps in powder metallurgy including mixing powders, compacting, and sintering to produce parts from metal powders.
3) The advantages of powder metallurgy which include a wide range of possible alloys and properties, close control over dimensions, and high material utilization.
Compression molding involves placing plastic material into a heated mold cavity, closing the mold, and applying pressure and heat to compress the material into shape. It is commonly used to make electrical components. Transfer molding similarly uses pressure to mold thermoset plastics, but involves transferring the material from a heated pot into the mold cavity. This document discusses these processes, providing details on their working principles, pros and cons, and an example of using compression molding to fabricate a microlens array from polycarbonate and glass for optical applications.
Powder metallurgy is a process that involves compacting and forming metal powders into a solid object through sintering. It consists of 3 main steps - producing metal powders through various methods, compacting the powders into a green compact through pressing, and sintering the compact by heating it to fuse the particles together into a solid object. It allows for net-shape production of complex parts and close dimensional tolerances, and is used for applications where other fabrication methods are not suitable.
Powder metallurgy involves producing metal powders and using them to make parts. There are several methods for powder production, including mechanical, chemical, and physical methods. Mechanical methods involve milling or grinding metals into powders, while chemical methods reduce metal oxides using reducing agents. Physical methods like gas or water atomization involve spraying molten metal into a chamber to produce spherical powders. The properties of metal powders depend on factors like particle size, shape, density and flow characteristics, which influence the powder metallurgy process steps of mixing, compacting, and sintering to produce final parts.
Transfer molding is a manufacturing process where a casting material is forced into an enclosed mold under pressure to form a casting. There are different types of transfer molding including resin transfer molding (RTM) and vacuum assisted resin transfer molding (VARTM). Thermoset polymers and fibers are common materials used. The transfer molding process involves placing the preheated molding compound in a transfer pot, closing the mold, and forcing the compound into the mold cavity under pressure where it cures. Applications include parts for the natural gas, electrical, and automotive industries. Advantages are uniform products and simpler production compared to other molding processes, while disadvantages include more material waste.
Isostatic pressing is a powder metallurgy technique that applies equal pressure in all directions to compact powdered materials. There are three main types - cold isostatic pressing, hot isostatic pressing, and warm isostatic pressing. Isostatic pressing allows for high density and uniform compaction of materials without the need for lubricants. It can be used to compact difficult materials like superalloys. The global isostatic pressing market was valued at $5.72 billion in 2017 and is projected to reach $9.22 billion by 2023, growing at a CAGR of 8.08% due to increasing demand for high-density 3D printed parts and investment in aerospace and defense applications
Shell moulding is a casting process that uses a sand-resin mixture to form a disposable mould around a reusable pattern. This allows for higher production rates than sand casting while also enabling more complex part geometries. The process involves creating a metal pattern, heating it, applying a sand-resin mixture to form shell halves, joining the shells to create the mould, pouring molten metal, and removing the casting after solidification. Shell moulding provides better dimensional accuracy, higher productivity, and lower labor costs than sand casting for small to medium precision parts.
This document discusses the process of powder metallurgy. It begins by introducing powder metallurgy and some of its advantages over traditional manufacturing methods. The main steps of the powder metallurgy process are then outlined, including powder manufacture through various techniques like atomization, blending to ensure uniformity, compacting the powder under pressure, sintering the compacted powder by heating it below the melting point, and final finishing operations. A variety of end products that can be created using powder metallurgy are listed such as bearings, gears, and regulators.
The document provides an overview of metal matrix composites (MMCs). It discusses that MMCs consist of a metal matrix reinforced with ceramic particles or fibers. The reinforcement improves the composite's properties over the unreinforced metal, such as increased strength and stiffness. The document also examines the important interfaces between the matrix and reinforcement, which influence the composite's performance. It describes various bonding mechanisms at the interface like mechanical, chemical, and diffusion bonding. Finally, the document outlines common processing techniques for fabricating MMCs, including powder metallurgy where metal powders are compacted and sintered to form the final composite material.
This document discusses various methods for producing metal powders, including mechanical, atomization, electrochemical, and chemical methods. Mechanical methods include chopping, abrasion, milling and the cold stream process. Atomization methods include gas, water, centrifugal atomization and using a rotating electrode. Factors that influence particle size and shape from atomization are also covered. Electrochemical production involves electrolysis of molten metals. Chemical methods decompose metal compounds with heat or catalysts. The document provides details on the principles, equipment used, advantages and limitations of each production method.
Super plastic forming is a metalworking process that uses high temperatures and controlled strain rates to form sheet metal. Materials like titanium alloys and aluminum alloys can elongate several times their original length through this process. Explosive forming also shapes metals through high pressure, using an explosive charge to form sheet metal against a die in either a standoff or contact method. Both processes allow for complex shapes but super plastic forming is slower while explosive forming supports larger parts and shorter production runs.
This document discusses powder metallurgy, including the typical process steps of metal powder production, characteristics of metal powders, compaction, sintering, and secondary operations. The key steps are producing metal powders using various methods, compacting the powder in a die to form a green compact, and sintering the compact at high temperature to bond the powder particles together without melting. Powder metallurgy allows for net-shape production of parts, uses little material waste, and can create porous or alloyed parts not possible with other methods.
This document discusses two mechanisms of plastic deformation in metals: slip and twinning. Slip involves the sliding of crystal blocks along crystallographic planes called slip planes, analogous to pushing cards in a deck. Twinning results in a mirrored orientation of a crystal portion. Slip is the primary deformation mechanism and occurs when shear stress exceeds a critical value, following Schmid's law. Twinning occurs when slip is not possible and results in a deformed mirrored grain. The document compares the characteristics and conditions of slip versus twinning.
Nanoindentation is a technique used to determine material properties such as hardness and elastic modulus at small length scales. It works by pressing an indenter with a very small tip into the material and measuring the resulting load and displacement. Factors like thermal drift, machine compliance, and real tip geometry must be accounted for when analyzing the load-displacement data to determine properties. Commercial nanoindentation machines use various methods like capacitive sensing or optical lever systems to precisely measure displacement during indentation testing.
This document provides information on various sheet metal forming processes. It discusses the characteristics of sheet metal and tests used to determine formability. The main sheet metal forming processes covered are tube bending and forming as well as bending of sheet and plate. Tube bending can be done via press bending, rotary drawing, heat induction, roll bending, and sand packing. Sheet and plate bending includes techniques like roll bending, air bending, bottoming, coining, folding, wiping, and rotary bending. Common applications of sheet metal forming in industries like automotive, aircraft, appliances, and furniture are also mentioned.
This document provides an overview of fused deposition modeling (FDM) 3D printing technology. It discusses that FDM works by extruding melted thermoplastic through a nozzle to build an object layer by layer. Common materials used are ABS and PLA plastics. FDM printers have advantages of a wide material selection and low cost, but lower accuracy than other technologies. Applications include prototyping, manufacturing tools and end-use parts for industries like automotive, aerospace, medical and more. In conclusion, FDM is well-suited for prototyping and less structurally demanding applications.
- Shell moulding is an efficient and economical casting method that uses a resin-sand mixture to form a thin "shell" around a heated pattern. This shell is then used as the mold cavity.
- Investment casting, also called lost-wax casting, is an ancient casting process used to produce complex shapes. It involves creating a wax pattern, coating it with refractory materials to form a ceramic "shell" mold, heating to remove the wax, and pouring molten metal into the shell. This allows for net-shape casting of intricate parts.
- Pressure die casting is a high-pressure casting process where molten metal is injected into steel dies to form castings. It is well-su
The document discusses rate controlled sintering in advanced ceramic processes. It explains that sintering transforms ceramic powder compacts into dense materials through heating by reducing pores and growing grains. The driving force is lowering free energy. Sintering occurs in three stages and is affected by various factors. Rate controlled sintering controls the heating rate or temperature to control the sintering process for improved material properties. It provides examples demonstrating the effects of heating rate on microstructure.
The document discusses various defects that can occur in metal forming processes. It describes the different types of bulk metal forming processes like rolling, forging, extrusion, and drawing. It also covers sheet metalworking processes like bending, drawing, and shearing. The document discusses factors that influence metal forming like material behavior, temperature, strain rate, friction, and lubrication. It explains defects like springback, wrinkles, and provides methods to minimize them.
Sintering is a process that uses heat to consolidate powder materials into a solid form without melting them. There are three main stages of sintering: initial bonding and neck formation between particles, densification and pore shrinkage, and final grain growth. The driving forces for sintering include reducing surface curvature, applied pressure, and chemical reactions. Key parameters that affect sintering include powder properties, consolidation method, firing temperature and atmosphere. The main mechanisms are surface, lattice, and grain boundary diffusion which allow atoms to migrate and bonds to form between powder particles over time.
Powder metallurgy involves compacting metal powder and sintering it to form solid parts. Key steps include powder production, blending/mixing, compaction, and sintering. Sintering heats the compacted powder below melting to allow atomic diffusion and bonding between particles. Powder metallurgy is useful for making complex, porous, or multi-material parts that are otherwise difficult to produce.
Compression molding involves placing plastic material into a heated mold cavity, closing the mold, and applying pressure and heat to compress the material into shape. It is commonly used to make electrical components. Transfer molding similarly uses pressure to mold thermoset plastics, but involves transferring the material from a heated pot into the mold cavity. This document discusses these processes, providing details on their working principles, pros and cons, and an example of using compression molding to fabricate a microlens array from polycarbonate and glass for optical applications.
Powder metallurgy is a process that involves compacting and forming metal powders into a solid object through sintering. It consists of 3 main steps - producing metal powders through various methods, compacting the powders into a green compact through pressing, and sintering the compact by heating it to fuse the particles together into a solid object. It allows for net-shape production of complex parts and close dimensional tolerances, and is used for applications where other fabrication methods are not suitable.
Powder metallurgy involves producing metal powders and using them to make parts. There are several methods for powder production, including mechanical, chemical, and physical methods. Mechanical methods involve milling or grinding metals into powders, while chemical methods reduce metal oxides using reducing agents. Physical methods like gas or water atomization involve spraying molten metal into a chamber to produce spherical powders. The properties of metal powders depend on factors like particle size, shape, density and flow characteristics, which influence the powder metallurgy process steps of mixing, compacting, and sintering to produce final parts.
Transfer molding is a manufacturing process where a casting material is forced into an enclosed mold under pressure to form a casting. There are different types of transfer molding including resin transfer molding (RTM) and vacuum assisted resin transfer molding (VARTM). Thermoset polymers and fibers are common materials used. The transfer molding process involves placing the preheated molding compound in a transfer pot, closing the mold, and forcing the compound into the mold cavity under pressure where it cures. Applications include parts for the natural gas, electrical, and automotive industries. Advantages are uniform products and simpler production compared to other molding processes, while disadvantages include more material waste.
Isostatic pressing is a powder metallurgy technique that applies equal pressure in all directions to compact powdered materials. There are three main types - cold isostatic pressing, hot isostatic pressing, and warm isostatic pressing. Isostatic pressing allows for high density and uniform compaction of materials without the need for lubricants. It can be used to compact difficult materials like superalloys. The global isostatic pressing market was valued at $5.72 billion in 2017 and is projected to reach $9.22 billion by 2023, growing at a CAGR of 8.08% due to increasing demand for high-density 3D printed parts and investment in aerospace and defense applications
Shell moulding is a casting process that uses a sand-resin mixture to form a disposable mould around a reusable pattern. This allows for higher production rates than sand casting while also enabling more complex part geometries. The process involves creating a metal pattern, heating it, applying a sand-resin mixture to form shell halves, joining the shells to create the mould, pouring molten metal, and removing the casting after solidification. Shell moulding provides better dimensional accuracy, higher productivity, and lower labor costs than sand casting for small to medium precision parts.
This document discusses the process of powder metallurgy. It begins by introducing powder metallurgy and some of its advantages over traditional manufacturing methods. The main steps of the powder metallurgy process are then outlined, including powder manufacture through various techniques like atomization, blending to ensure uniformity, compacting the powder under pressure, sintering the compacted powder by heating it below the melting point, and final finishing operations. A variety of end products that can be created using powder metallurgy are listed such as bearings, gears, and regulators.
The document provides an overview of metal matrix composites (MMCs). It discusses that MMCs consist of a metal matrix reinforced with ceramic particles or fibers. The reinforcement improves the composite's properties over the unreinforced metal, such as increased strength and stiffness. The document also examines the important interfaces between the matrix and reinforcement, which influence the composite's performance. It describes various bonding mechanisms at the interface like mechanical, chemical, and diffusion bonding. Finally, the document outlines common processing techniques for fabricating MMCs, including powder metallurgy where metal powders are compacted and sintered to form the final composite material.
This document discusses various methods for producing metal powders, including mechanical, atomization, electrochemical, and chemical methods. Mechanical methods include chopping, abrasion, milling and the cold stream process. Atomization methods include gas, water, centrifugal atomization and using a rotating electrode. Factors that influence particle size and shape from atomization are also covered. Electrochemical production involves electrolysis of molten metals. Chemical methods decompose metal compounds with heat or catalysts. The document provides details on the principles, equipment used, advantages and limitations of each production method.
Super plastic forming is a metalworking process that uses high temperatures and controlled strain rates to form sheet metal. Materials like titanium alloys and aluminum alloys can elongate several times their original length through this process. Explosive forming also shapes metals through high pressure, using an explosive charge to form sheet metal against a die in either a standoff or contact method. Both processes allow for complex shapes but super plastic forming is slower while explosive forming supports larger parts and shorter production runs.
This document discusses powder metallurgy, including the typical process steps of metal powder production, characteristics of metal powders, compaction, sintering, and secondary operations. The key steps are producing metal powders using various methods, compacting the powder in a die to form a green compact, and sintering the compact at high temperature to bond the powder particles together without melting. Powder metallurgy allows for net-shape production of parts, uses little material waste, and can create porous or alloyed parts not possible with other methods.
This document discusses two mechanisms of plastic deformation in metals: slip and twinning. Slip involves the sliding of crystal blocks along crystallographic planes called slip planes, analogous to pushing cards in a deck. Twinning results in a mirrored orientation of a crystal portion. Slip is the primary deformation mechanism and occurs when shear stress exceeds a critical value, following Schmid's law. Twinning occurs when slip is not possible and results in a deformed mirrored grain. The document compares the characteristics and conditions of slip versus twinning.
Nanoindentation is a technique used to determine material properties such as hardness and elastic modulus at small length scales. It works by pressing an indenter with a very small tip into the material and measuring the resulting load and displacement. Factors like thermal drift, machine compliance, and real tip geometry must be accounted for when analyzing the load-displacement data to determine properties. Commercial nanoindentation machines use various methods like capacitive sensing or optical lever systems to precisely measure displacement during indentation testing.
This document provides information on various sheet metal forming processes. It discusses the characteristics of sheet metal and tests used to determine formability. The main sheet metal forming processes covered are tube bending and forming as well as bending of sheet and plate. Tube bending can be done via press bending, rotary drawing, heat induction, roll bending, and sand packing. Sheet and plate bending includes techniques like roll bending, air bending, bottoming, coining, folding, wiping, and rotary bending. Common applications of sheet metal forming in industries like automotive, aircraft, appliances, and furniture are also mentioned.
This document provides an overview of fused deposition modeling (FDM) 3D printing technology. It discusses that FDM works by extruding melted thermoplastic through a nozzle to build an object layer by layer. Common materials used are ABS and PLA plastics. FDM printers have advantages of a wide material selection and low cost, but lower accuracy than other technologies. Applications include prototyping, manufacturing tools and end-use parts for industries like automotive, aerospace, medical and more. In conclusion, FDM is well-suited for prototyping and less structurally demanding applications.
- Shell moulding is an efficient and economical casting method that uses a resin-sand mixture to form a thin "shell" around a heated pattern. This shell is then used as the mold cavity.
- Investment casting, also called lost-wax casting, is an ancient casting process used to produce complex shapes. It involves creating a wax pattern, coating it with refractory materials to form a ceramic "shell" mold, heating to remove the wax, and pouring molten metal into the shell. This allows for net-shape casting of intricate parts.
- Pressure die casting is a high-pressure casting process where molten metal is injected into steel dies to form castings. It is well-su
The document discusses rate controlled sintering in advanced ceramic processes. It explains that sintering transforms ceramic powder compacts into dense materials through heating by reducing pores and growing grains. The driving force is lowering free energy. Sintering occurs in three stages and is affected by various factors. Rate controlled sintering controls the heating rate or temperature to control the sintering process for improved material properties. It provides examples demonstrating the effects of heating rate on microstructure.
The document discusses various defects that can occur in metal forming processes. It describes the different types of bulk metal forming processes like rolling, forging, extrusion, and drawing. It also covers sheet metalworking processes like bending, drawing, and shearing. The document discusses factors that influence metal forming like material behavior, temperature, strain rate, friction, and lubrication. It explains defects like springback, wrinkles, and provides methods to minimize them.
Sintering is a process that uses heat to consolidate powder materials into a solid form without melting them. There are three main stages of sintering: initial bonding and neck formation between particles, densification and pore shrinkage, and final grain growth. The driving forces for sintering include reducing surface curvature, applied pressure, and chemical reactions. Key parameters that affect sintering include powder properties, consolidation method, firing temperature and atmosphere. The main mechanisms are surface, lattice, and grain boundary diffusion which allow atoms to migrate and bonds to form between powder particles over time.
Powder metallurgy involves compacting metal powder and sintering it to form solid parts. Key steps include powder production, blending/mixing, compaction, and sintering. Sintering heats the compacted powder below melting to allow atomic diffusion and bonding between particles. Powder metallurgy is useful for making complex, porous, or multi-material parts that are otherwise difficult to produce.
Powder metallurgy involves blending metal powders, compacting them under pressure into a desired shape, and then sintering the compressed material at high temperatures to bond it together. The key steps are compacting powdered materials into a shape and then sintering to fuse the materials. Powder metallurgy allows forming complex shapes without extensive machining and has been used since ancient times to produce metal objects.
This document discusses powder metallurgy, including its definition, advantages, limitations, applications, and basic production steps. Powder metallurgy involves blending metal powders, compacting them into a desired shape, and sintering the compact to bond the particles. It allows for net-shape production, close tolerances without machining, and complex alloy compositions. Common applications include gears, bearings, and electrical contacts. The basic steps are powder production, blending, compaction in a die, and sintering to densify and strengthen the part. Design considerations for powder metallurgy parts include simple shapes, adequate wall thickness, and avoiding undercuts.
Slip casting is a process used to mass produce ceramic items like figurines, dishes, and flower pots. A liquid suspension of ceramic powder called a slip is poured into a plaster mold. Water from the slip is absorbed by the porous mold, leaving a solid ceramic layer. Excess slip is drained out. The piece is then dried and fired. There are two main methods - drain casting produces hollow items while solid casting allows the entire mold cavity to solidify. Key factors that affect the process include the viscosity and setting rate of the slip as well as shrinkage and strength of the final piece. Slip casting allows intricate shapes and sizes but the process is slow with limited commercial applications.
Powder metallurgy is a process that involves blending metal powders, compacting them under pressure into a desired shape, and then sintering or heating the compact to fuse the particles together. It allows for the production of small, intricate parts with complex shapes from difficult-to-machine materials. Common applications include automotive components, gears, bearings, and appliances. The key steps are powder production through atomization, blending and mixing, compaction, and sintering.
Powder pressing is used to compact powders into a geometric form called a green compact. This creates a solid part with some strength that can be handled before sintering. The document discusses the powder pressing process, including filling powder into a die, compacting it with a punch to the desired shape and density, and the importance of lubrication. It also covers the mechanics of how powder particles rearrange and bond together during pressing through mechanisms like plastic deformation and cold welding.
Compaction and compression, Forces involved in compression & Factors affectin...Dharmendra Chaudhary
This document summarizes key aspects of compaction and compression presented in a seminar. It discusses how compaction involves applying mechanical force to powdered solids, consolidating the material and increasing particle interaction. It also describes various forces involved in compression, including the applied force, force transmitted to the lower punch, and die wall friction. Factors affecting tablet hardness are compression force magnitude and distribution within the die, as well as material properties like plasticity and stress relaxation rate.
Powder metallurgy (P/M) is used to produce parts when other metalworking processes cannot be used due to high melting points or difficulty in machining. P/M involves producing metal powders, blending them with other powders, compacting the blended powder into a "green" part, sintering the part to bond the powders together, and finishing the part. Near 70% of P/M production is for automotive applications due to its ability to produce parts with good dimensional accuracy and controllable porosity.
Experimental Investigation and Analysis of Extrusion of Lead from Round Secti...IOSR Journals
Abstract : An experimental investigation has been done on the changes of die angle, area reduction in dies,
loading rate on the final extruded products, extrusion pressures of lead of circular cross sections of different
length. The proposed method is successfully adapted to the extrusion of the equilateral triangular section from
round billet through converging dies of different area reductions. Computation of extrusion pressure at various
area reductions and finite element analysis of different parameters (stress, strain, velocity) both in dry and wet
condition.
Keywords - Converging dies, Extrusion of the equilateral triangular section, Extrusion Pressure
Investigation of Extrusion of Lead experimentally from Round section through ...inventy
ABSTRACT :The changes of die angle, area reduction in dies, loading rate on the final extruded products, extrusion pressures of lead of circular cross sections has been investigated experimentally. The proposed method is successfully adapted to the forward extrusion of the equilateral triangular section from round billet through converging dies of different area reductions. Computation of extrusion pressure at various area reductions and calculations of different parameters (stress, strain etc.) in wet condition.
Keywords - Extrusion of Triangular section, Converging Dies at different area reductions, Friction Factor, Extrusion Pressure
Presentation for Jindal steels prepared on 02/01/2021 by
Dr. R. Narayanasamy, Retired Professor, Department of Production Engineering, NIT - Trichy, Tamil Nadu, India. Chief metallurgist, Balaji Super Alloys, Karamadai, Coimbatore - 641104, Tamil Nadu, India.
This document describes a photoelastic stress analysis of the bending strength of a helical gear. The analysis involved creating a 3D photoelastic model of the gear, subjecting it to loading, and freezing the stresses. Slices were cut from the model and observed under polarized light to determine stress distributions. Maximum bending stresses were calculated for different slices and scaled up to prototype values. Finite element analysis was also performed and showed good agreement with experimental results, with less than 2% variation in maximum stress values. The analysis found that helical gears experience higher peak bending stresses than spur gears due to their point contact loading.
Study on the Effect of Stress Concentration on Cutout Orientation of Plates w...IJMER
This document analyzes stress concentration in perforated aluminum plates with various cut-out shapes, degrees of bluntness at cut-out edges, and cut-out orientations. Finite element analysis was conducted on plates with circular, square, and triangular cut-outs having different radius ratios representing bluntness. Cut-outs were also oriented at 15, 30 and 45 degree rotations. Stress concentration factor increased with sharper cut-out edges and orientations farther from the loading direction. The highest stress occurred for a triangular cut-out with minimal bluntness oriented at 30 degrees. Understanding how cut-out design affects stress distribution can help optimize lightweight structures.
The document discusses stress concentration and fatigue failure in machine elements. It defines stress concentration as the localization of high stresses due to irregularities or abrupt changes in cross-section. Stress concentration can be reduced by avoiding sharp changes in cross-section and providing fillets and chamfers. Fatigue failure occurs when fluctuating stresses cause cracks over numerous load cycles. The endurance limit is the maximum stress amplitude that causes failure after an infinite number of cycles. Factors like stress concentration, surface finish, size, and mean stress affect the endurance limit. Designs should minimize stress raisers and protect against corrosion to prevent fatigue failures.
The document compares residual stress in equal matching and undermatching weld joints of high strength steel thick plates through numerical simulation. The simulation found that equivalent stress and longitudinal stress were significantly lower in undermatching welds compared to equal matching welds, while transverse stresses were similar. Stress maximums in equal matching welds occurred in both the weld and heat affected zone, while undermatching welds only showed stress maximums in the heat affected zone. The undermatching weld configuration is an effective way to reduce residual stress and avoid cold cracking in high strength steel thick plate welding.
This document provides information about flexural testing of materials including steel, pine, and Douglas fir. It includes the experimental setup, procedures, formulas used to calculate flexural properties, graphs of load vs deformation, and tables of test data for each material. The key results are the ultimate flexural strengths of 2.2 kips for steel, 1.05 kips for pine, and still to be determined for Douglas fir. Comparisons are made between the flexural properties of the different materials.
Dr. R. Narayanasamy - Presentation on Formability of Deep Drawing Grade SteelsDr.Ramaswamy Narayanasamy
Step 1: The document summarizes a presentation given by Dr. Ramaswamy Narayanasamy on the formability of deep drawing grade steels.
Step 2: It provides details of the speaker's achievements and scientific contributions related to sheet metal forming and formability studies on various steel grades.
Step 3: The presentation describes the methodology used to construct forming limit diagrams (FLDs), including the different strain conditions tested, grid circle marking on sheet specimens, measurement of strain after deformation, and plotting of the FLD curves.
Analysis of Stress Distribution in a Curved Structure Using Photoelastic and ...IOSR Journals
1) The document analyzes stress distribution in a curved structure subjected to uniaxial tension using photoelastic and finite element methods.
2) Photoelasticity is used to experimentally determine stress distribution in models of the curved structure with and without circular and elliptical stress relievers. Finite element analysis is then used to validate the experimental photoelastic results.
3) The study found that an elliptical stress reliever with its major axis normal to the load more effectively reduced stress concentration at the inner boundary of the curved structure compared to a circular stress reliever.
1. The document analyzes stress distribution in a curved structure subjected to uniaxial tension using photoelastic and finite element methods.
2. It introduces circular and elliptical stress relievers in the low stress region to reduce weight without affecting strength. The elliptical stress reliever with major axis normal to loading reduced stress intensity by 2% compared to the original structure.
3. Results from photoelastic experiments matched well with finite element analysis simulations. The experimental method provided precise stress values regardless of geometric complexity, while finite element analysis was less time consuming and helped optimize the stress reliever geometry.
Analysis of Stress Distribution in a Curved Structure Using Photoelastic and ...IOSR Journals
1. The document analyzes stress distribution in a curved structure subjected to uniaxial tension using photoelastic and finite element methods.
2. It introduces circular and elliptical stress relievers in the low stress region to reduce weight without affecting strength. The elliptical stress reliever with major axis normal to loading reduced stress intensity by 2% compared to the original structure.
3. Results from photoelastic experiments matched well with finite element analysis simulations. The experimental method provided precise stress values regardless of geometric complexity, while finite element analysis was less time consuming and helped optimize the stress reliever geometry.
Modeling of Rough Surface and Contact Simulationijsrd.com
As a result of limitation of manufacturing processes, real surfaces always have some roughness and surface curvature. In many heat transfer applications, the perfectly smooth surfaces are necessary to transmit the heat. Due to the surface curvature of contacting bodies, the macro-contact area is formed, the area where micro-contacts are distributed randomly. The real contact occurs only over microscopic contacts. The heat flow must pass through the macro-contact and then micro-contacts to transfer from one body to another to form heat conductance. This phenomenon leads to a relatively high temperature drop across the interface. Thermal contact resistance (TCR) is a complex interdisciplinary problem, which includes geometrical, mechanical, and thermal analyses. In this paper, geometric modeling of asperities of rough surface 2 μm, 3.2 μm and 15μm surface roughness's is done in ANSYS and the number of asperities and areal contact area is found. The simulation is done with 1.8MPa pressure and with SS 304 as material for all above mentioned surface roughness's. The contacting bodies are kept at LN2 temperature and atmospheric temperature.
A closed form solution for stress concentration around a circular hole in a lIAEME Publication
1) The document presents a closed-form solution to determine stress concentration around a circular hole in an infinite plate with linearly varying stress.
2) The equation developed can determine stress field around the hole without need for computationally intensive numerical methods.
3) Results from the closed-form solution are compared to finite element analysis and show close agreement.
A closed form solution for stress concentration around a circular hole in a lIAEME Publication
This document presents a closed-form solution for determining stress concentration around a circular hole in an infinite plate with linearly varying stress. The plate is subjected to a tensile stress that varies linearly from the top edge to the bottom edge. An equation is derived for the stress field in polar coordinates using stress functions. Boundary conditions are applied at the hole edge and at a large distance from the hole. A solution is obtained for the stresses around the hole in terms of constants and the original varying stress field, without requiring numerical methods. The results are compared to finite element analysis and show close agreement.
The Comparison of Properties of Tinplates during Uniaxial and Biaxial Stresstheijes
The majority of thin steel sheets is used to make of food covers, cans, capsules and other products, which are produced by metal forming. Concerning considerable changes in production of tinplates and still higher requests on their properties there is requirement to use such methods on their evaluation, which are able to determine especially mechanical and plastic properties of sheets quickly and with the low costs. Following of present know-how there were developed new testing methods, which correspond more to steel sheets stress during technological treatment (concerning their stress-strain state). In the contribution we deal with the comparison of properties of tinplates during uniaxial tensile test and biaxial tensile test.
This document provides an abstract for a master's thesis on numerical analysis of residual stress on plate girders. The abstract indicates that the thesis addresses the prediction of imperfections in plate girders using simulation tools and simplified engineering models. It evaluates the impact of these imperfections, with a special focus on the effect of residual welding stress. Different simplified stress distributions are compared to results from welding simulation to validate recommendations on implementing weld-induced imperfections.
Root Fillet Stress Reduction in Spur Gear having UndercutIJLT EMAS
Generally the gear tooth fails due to high stress at root
region. Even a slight reduction in the stress results in greater
increase in life of the gear. For a compact design of a gear box, it
is necessary that the number of teeth of the pinion should be less
.For a given pressure angle there is a limiting value on minimum
number of teeth below which undercut occurs. The spur gear
with undercut suffers in strength severely. Therefore the gears
with undercut are generally avoided. The present work explores
the possibilities of increasing the strength of spur gear having
undercut thereby reduce the overall size of the gearbox. A
systematic study is conducted to understand the effect of
introducing circular stress relief features on stress distribution in
a statically loaded spur gear. Circular stress relief features of
various sizes at different radial distance and angular position are
placed around the end point on critical section on loaded side of
the gear tooth profile. Effect of these stress relief feature on
maximum stress are investigated.
This document provides lecture notes on metal forming processes. It covers topics such as stress and strain analysis, yield criteria, plasticity theory, and different metal forming methods like rolling, forging, extrusion, and sheet metal working. It also discusses concepts like hot working, strain hardening, and the relationship between true stress and engineering stress. The notes are divided into 5 units covering these various metal forming topics.
The document discusses design considerations for machine elements subjected to fluctuating loads. It covers topics such as stress concentration, fatigue failure, endurance limit, factors affecting fatigue strength, and methods to reduce stress concentration and improve fatigue life. Stress concentration occurs due to discontinuities and can be reduced by avoiding abrupt changes in cross-section and providing fillets. Fatigue failure is caused by fluctuating stresses and depends on factors like the number of cycles and mean stress. The endurance limit is the maximum stress amplitude a material can withstand without failure under completely reversed loading. Surface finish, size, and mean stress affect the endurance limit.
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4. Die compaction
Consolidation of powder by the application of uniaxial
stress while the powder is constrained in rigid tooling.
Powders from the feed hopper at apparent density in
placed in die cavity.
Particles rearrange, deform and bond because of pressure
applied by punch.
Deformation hardens the particles and hence, more
pressure is applied to the powder.
After attaining maximum hardness, there is no density
change with further application of compaction pressure.
The compaction pressure ranges up to 1000MPa. (Depends
on powder and tool material)
Soft powders (ex: Al powders attains more green density
(~90%) with less compaction pressure ~ 150 MPa)
Hard powders (ex: cemented carbide attains ~ 60% green
density for the compaction pressure of ~175MPa).
9. Conventional P/M Route
Compaction relative density R=(ρf /ρth) > 0.70 (or)
70%
During sintering, there is 4 to 5% increase in R
During cold working, (Example: Cold upsetting) there
is 12% increase in R
During hot working, there is more than 20% increase
in R
10. (a) (b) (a) (b)
Pressures mobilized during
single action die compaction, a)
without and b) with lubricant.
Pressures mobilized during a)
free mould (wet – bag) and b)
fixed mould (dry – bag) isostatic
compaction.
12. Unidirectional compaction: Single action
pressing
Vertical pressure is applied to powder
Friction occurs between powder and die walls
Non uniform pressure distribution along sides of
compacts
Pressure gets reduced at the base of compacts.
13. Unidirectional compaction: Double
action pressing
Produce equal pressure at top and bottom of compacts
Friction in side walls are reduced by lubricants which
enhances the lateral pressure
Final global stress state is not uniform
Parts with large height to diameter ratios and complex
shapes cannot be compacted
But, used in where large production rates are required
14. Isostatic compaction/ Hydrostatic
compaction
Powder is placed in a flexible mould (rubber) and
immersed into a pressure vessel and compacted using
hydorstatic pressure
This method is flexible with part size and shape
The final global stresses are isostatic around the compacts
The production rate is low. To overcome this, a slight
modification with fixed mould (upper and lower end with
rigid part) and side walls with rubber was introduced
This modified setup leads to low axial pressure than lateral
pressure
15. Triaxial compaction
Setup is similar to fixed mould isostatic pressing
Lateral and axial pressures can be controlled separately
Shear stress within compacts enhance green density and
strength
Torsional shear stress is applied (either by load piston or
rotation of tool)
The minor principal stress (σ3) is uniform in all directions
Axial pressure is applied by the piston which increases axial
stress (σ1)
The resulting principal stress difference (σ1 - σ3 = 2τ)
The above is nothing but Tresca Yield criteria
16.
17. Mohr stress space diagrams
In fig. (a), confining pressure is increased to produce σ3 in all
directions (horizontal dotted line)
Axial stress (σ1) is increased along with increase in average
normal stress and also produce a shear stress (angular dotted
line)
The various combinations of stress paths are shown in fig. (b).
Stress path (1) reduces total time of compaction with low green
density compared to other stress paths.
Stress path (5) produces high green density compacts with high
confining pressure than other stress paths.
Stress path (3) is the representation of fig.(a) which is optimum.
There is a limit for shear stress for compaction in rigid moulds.
Further increase in shear stress will lead to shear failure.
A failure plane propagation is approximately 45°
18.
19. Stress and volumetric strain versus axial strain
response curves for green iron compacts at various
confining pressures.
The peak stress in each curve denotes shear failure.
Increasing confining pressure increases the principal stress
difference (shear stress). Hence, the sample’s shear strength is
increased.
Axial strain at failure increases with decreasing confining pressure.
As the difference between principal stresses increases, the axial
strain at failure also increases.
Modulus of elasticity increases with increasing confining pressure.
Green density also increases with increasing in confining pressure.
Volume decrease is high when the compacts have low green density
(or) the difference between principal stresses decreases.
Under shear stress, different types of iron powders behave similarly.
21. Mohr’s circle (three – dimensional) for the state of
stress
Uniaxial tension
- σ σ
σ1
τ max=σ1/ 2
τ
σ2 = σ3 = 0
(a
)
3
2
22. Mohr’s circle (three – dimensional) for the state of
stress
Uniaxial compression
σ1 = σ2 = 0
σ3
τ
max
2
1
23. Mohr’s circle (three – dimensional) for the state of stress
biaxial tension
σ3 = 0
σ2
σ1
τ max =
τ2
τ1 τ3
3
σ2
σ1 = 2σ2
24. Mohr’s circle (three – dimensional) for the state of stress
biaxial compression
σ1
σ3 = 0
τ1τ3
σ2
σ2
3
τ max =
τ2
σ1 = 2σ2
25. Mohr’s circle (three – dimensional) for the state of stress
triaxial tension (unequal)
σ1
σ2 = σ3
τ max = τ2 =τ3
σ3
σ2
σ1 = 2σ2 = 2σ3
26. Mohr’s circle (three – dimensional) for the state of stress
triaxial compression (unequal)
σ2 = σ3
σ1
τ max = τ2 =τ3
σ2
σ3
27. Mohr’s circle (three – dimensional) for the state of stress
uniaxial tension plus biaxial compression
σ2 = σ3
σ1
τ max = τ2 =τ3
σ3
σ2
σ1 = -2σ2 = -2σ3
28.
29. Failure envelope on Mohr stress space for green
iron compacts
Curve drawn tangent to Mohr’s circles indicates the
failure envelope.
Above this shear stress, failure takes place by shear.
The failure envelope is in a linear pattern with
approximately 5° angle to the horizontal line.
This is in good agreement with Schwartz et al.
In empirically fitted log-log sheet, the equation of
failure curve is τ = 3.52 σ ^ 0.48
where τ – shear stress and σ – normal stress.
30. ISOSTATIC DENSITY
AT 100 ksi = 90.4%
PERCENTAGETHEORITICAL
DENSITY
SHEAR STRESS τ , ksi
0 20 40 60 80 100 120
PRINCIPAL STRESS DIFFERENCE σ1 – σ3 , ksi
For decreasing
confining pressure
31. 6 6.5 7
EDGE
CTR.
EDGE
ISOSTATIC AT 30,000 psi
GREEN DENSITY GREEN DENSITY
ISOSTATIC AT 60,000 psi
EDGE
CTR.
EDGE
6.5 7 7.5
Radial density gradients of isostatically compacted iron powder at
different levels of confining pressure. (1 ksi = 6.9 MPa.)
32. 6.5 7 7.5
EDGE
CTR.
EDGE
Radial density gradients of triaxially compacted iron powder at
different levels of confining pressure. (1 ksi = 6.9 Mpa.)
GREEN DENSITY
TRIAXIAL AT 30,000 psi
7 7.5 8
TRIAXIAL AT 60,000 psi
EDGE
CTR.
EDGE
33. Radial density gradients of isostatically and
triaxially compacted iron powder at different
levels of confining pressure
Atomized iron powder was used in this study.
Radial density variation was measured by subsequently
machining the compacts up to the core.
At 30,000 psi, Isostatic compact has high density at edge than
centre (variation: ~ 0.23g/cm^3).
Particles closer to the edge are plastically deformed and
compacted compared to the core.
At 60,000 psi, Isostatic compaction shows less density variation
(~ 0.10 g/cm^3) across the radial distance.
At 30,000 psi, triaxial compaction shows same tendency with
density variation of ~ 0.19 g/cm^3.
At 60,000 psi, triaxial compaction shows no density variation
across the radial distance.
34. Vertical density gradients of isostatically compacted iron powder at
different levels of confining pressure. (1 ksi = 6.9 Mpa.)
35. Vertical density gradients of triaxially compacted iron powder at
different levels of confining pressure. (1 ksi = 6.9 Mpa.)
36. Vertical density gradients of isostatically and
triaxially compacted iron powder at different
levels of confining pressure
Vertical density variation was obtained by sectioning the
compacts horizontally.
At 30,000 psi, isostatic compaction shows high density at centre
than top and bottom with a density variation of ~0.2 g/cm^3.
At 60,000 psi, isostatic compaction shows density variation of
~0.15g/cm^3
At 30,000 psi, triaxial compaction shows higher overall density
with less variation of density between top and bottom.
At 60,000 psi, triaxial compaction shows density variation of ~
0.03g/cm^3
Triaxial compaction is better than isostatic compaction.
As the H/D ratio of compact increases, the density variation will
be larger.
37. 60
70
80
90
100
0 20 40 60 80 100
No Shear
High Shear
Medium Shear
Low Shear
TRANSVERSE RUPTURE STRENGTH (ksi)
PERCENTTHEORETICALDENSITY
Density versus transverse rupture strength for isostatically and triaxially
compacted on powder compacts showing the influence of shear stress: no shear;
low shear (0-17 ksi); medium shear (17-24 ksi); high shear (34-50 ksi). (1 ksi = 6.9
MPa.)
38. Density versus transverse rupture strength for
isostatically and triaxially compacted on powder
compacts showing the influence of shear stress
For the given green density, compacts formed under
high shear stress have greater strength.
At 90% theoretical density, compacts formed by high
shear stress have more than twice the strength of
isostatic compacts.
Shear stress during compaction increases the green
density and the strength.
45. Compaction of Metal Powders by Cold
Isostatic Pressing
Metal powder is placed in a
flexible rubber mold made
of neoprene rubber,
urethane, polyvinyl
chloride (PVC).
The assembly is then
pressurized hydrostatically
in a chamber, by water.
Most common pressure:
400MPa.
47. Die insert and liner
It is a removable liner used to minimize too wear,
which is fabricated out of hard materials (ex:
cemented carbide)
Die insert will be in contact with the component.
A liner is similar to this, formed as a coating or hard
electroplated layer
48. Die wall friction
Applied uniaxial load makes the powder to deform and
spread laterally.
This lateral pressure is against the tooling and creates
wall friction.
Wall friction reduces powder flow and sliding during
compaction.
Continual pressure loss with distance from the punch
as the powder bleeds off the applied pressure in the
form of die wall friction.
49. Die wall lubrication
External spray is dispersed on the die wall after every
compaction.
The die wall lubrication is introduced via seal ring
built into the lower punch. As the punch moves to the
fill position, it will leave a lubricant film on the die
walls.
Electrostatic spray with an external dispersion unit.
Lubricant can be mixed with powders
Molybdenum disulphide is used as lubricant
50. Compaction of Metal Powders by
other Processes
Rolling:
Powder is fed to the
roll gap in 2-high
rolling mill, and is
compacted into a
continuous strip at
speeds of up to 0.5 m/s.
Rolling process carried
out at room or at elevated
temperature.
Common parts: Sheet
metal for electrical and
electronic components
and for coins.
51. Compaction of Metal Powders by
other Processes
Powder Extrusion:
Powder is incased in a metal container and extruded.
After sintering, preformed PM parts may be reheated and
then forged in a closed die to their final shape.
52. Sinter forging
Applicable for ceramic parts
Ceramic deformation takes
place at a very slow strain rate.
Limited plastic flow capacity
(for hot ceramics stress and
stain will be low)
The cycle time is long.
The slow deformation appears
like forging.
The stress is low and the
densification and shaping rates
are controlled by diffusional
creep.
53. Powder sinter forging
No sintering stage is involved.
Loose powders are compacted and then hot forged.
This is called sinter forging
56. Powder compaction equations cont…
Panelli and Ambrozio Filho equation:
Ge equation:
Where
D- relative density of the compacted material
P- applied pressure
and others are constants
57. Powder compaction equation cont…
Findings of Narayanasamy et al.
The compaction data were best fitted to the Ge
equation for studying the densification behavior of
nano composite.
The above is Narayanasamy and Jeyasimman work
for AA 6061 nano composites reinforced with hybrid
(TiC + Al2O3) nano particles.
58. Powder compaction equations cont…
Van Der Zwan and Siskens equation:
Where
D – relative density of the post compacts
- relative apparent density
and others are constants
Van Der Zwan and Siskens equation is the well fitted equation
according to Narayanasamy and Sivasankaran.
It can be used for analyzing the compaction behavior of powders
as applicable and useful to P/M industries.
D0
59. Theory of Plasticity for powder - sinter
forging
Uniaxial stress state condition:
In the compression of a P/M part, under frictional conditions,
the average density is increased. Friction enhances densification
and at the same time decreases the height reduction at fracture.
The state of stress in a homogeneous compression process is as
follows:
According to Abdel-Rahman et al.
σz = −σeff , σr = σθ = 0 – (1)
where
σz - axial stress
σeff - effective stress
σr - radial stress
Σθ - Hoop stress.
60. Theory of Plasticity for powder -
sinter forging cont ….
- (2)
σm - mean or hydrostatic stress
- (3)
ε0 – hoop strain
εz – axial strain
D0 – initial diameter of the compacts
Df – contact diameter after deformation
61. Theory of Plasticity for powder
- sinter forging cont ….
Where
H0 - initial height of the compacts
Hf – fracture height of the compacts
When the compression continues, the final diameter increases and the
corresponding hoop strain, which is tensile in nature, also increases until it
reaches the fracture limit. Once the fracture is initiated, the forming limit strain is
the same as the effective strain. It is determined from:
62. Theory of Plasticity for powder -
sinter forging cont ….
As an evidence of experimental investigation implying
the importance of the spherical component of the
stress state on fracture according to Vujovic and
Shabaik proposed a parameter called a formability
stress index ‘β’ which is given by:
This index determines the fracture limit
63. Theory of Plasticity for powder - sinter
forging cont ….
Plane stress state condition
According to Narayanasamy and Pandey, the state of
stress in a plane stress condition is as follows:
where σeff is the effective stress,
Where α is the Poisson’s ratio and σz is the axial stress in upsetting.
64. Theory of Plasticity for powder - sinter
forging cont ….
Since the radial stress, σr is zero at the free surface it
follows from the flow rule that:
σm - mean or hydrostatic stress is :
The hoop strain (εθ) of the compact is determined
by this equation
where
Db - bulged diameter of the
compacts
Dc - contact diameter of the
compacts
Do - initial diameter of the
compacts.
65. Theory of Plasticity for powder - sinter
forging cont ….
Triaxial stress state condition
According to Narayanasamy and Ponalagusamy,
The state of stress in a triaxial stress condition is given as
follows:
67. Theory of Plasticity for powder - sinter
forging cont ….
The effective stress can be determined from the
following relation:
According to Doraivelu et al.
(or)
for axisymmetric condition
68. Theory of Plasticity for powder - sinter
forging cont ….
Once we know σm and σeff ,we can determine the
formability stress index (β).
The formability stress index will tell you to what
extend the metal can be forged.
β is constant for uniaxial compression forging and this
value is 0.33.
For plane stress and triaxial condition, it has a range of
values.
For hot forging, the β value is very high compared to
cold forging.
69. Theory of Plasticity for powder - sinter
forging cont ….
According to Narayanasamy et al., the formability
strain index parameter is defined as follows:
70. Theory of Plasticity for powder - sinter
forging cont ….
The behaviour of and are same.
Narayanasamy et al., proposed pore closure index
parameters based on , , n, m and R value.
72. References
D. Jeyasimman, K. Sivaprasad, S. Sivasankaran, R. Ponalagusamy, R. Narayanasamy, Vijayakumar Iyer
“Microstructural observation, consolidation and mechanical behaviour of AA 6061 nanocomposites
reinforced by γ-Al2O3 nanoparticles”,Advanced Powder Technology, Volume 26, Issue 1, January 2015, Pages 139-148.
D. Jeyasimman, R. Narayanasamy, R. Ponalagusamy, V. Anandakrishnan, M. Kamaraj, “The effects of various
reinforcements on dry sliding wear behaviour of AA 6061 nanocomposites”, Materials & Design, Volume 64,
December 2014, Pages 783-793.
Ilangovan Arun, Muthukannan Duraiselvam, V. Senthilkumar, R. Narayanasamy, V. Anandakrishnan,“Synthesis of
electric discharge alloyed nickel–tungsten coating on tool steel and its tribological studies”,Materials &
Design, Volume 63, November 2014, Pages 257-262.
B. Selvam, P. Marimuthu, R. Narayanasamy, V. Anandakrishnan, K.S. Tun, M. Gupta, M. Kamaraj,“Dry sliding wear
behaviour of zinc oxide reinforced magnesium matrix nano-composites”,Materials & Design, Volume 58, June
2014, Pages 475-481.
D. Jeyasimman, S. Sivasankaran, K. Sivaprasad, R. Narayanasamy, R.S. Kambali, “An investigation of the synthesis,
consolidation and mechanical behaviour of Al 6061 nanocomposites reinforced by TiC via mechanical
alloying”,Materials & Design, Volume 57, May 2014, Pages 394-404.
D. Jeyasimman, K. Sivaprasad, S. Sivasankaran, R. Narayanasamy, “Fabrication and consolidation behavior of Al
6061 nanocomposite powders reinforced by multi-walled carbon nanotubes”,Powder Technology, Volume 258,
May 2014, Pages 189-197.
S.C. Vettivel, N. Selvakumar, R. Narayanasamy, N. Leema, “Numerical modelling, prediction of Cu–W nano
powder composite in dry sliding wear condition using response surface methodology”,Materials & Design,
Volume 50, September 2013, Pages 977-996.
A.P. Mohan Raj, N. Selvakumar, R. Narayanasamy, C. Kailasanathan, “Experimental investigation on workability
and strain hardening behaviour of Fe–C–Mn sintered composites with different percentage of carbon and
manganese content”, Materials & Design, Volume 49, August 2013, Pages 791-801.
73. References cont….
M. Srinivasan, C. Loganathan, R. Narayanasamy, V. Senthilkumar, Q.B. Nguyen, M. Gupta, “Study on hot
deformation behavior and microstructure evolution of cast-extruded AZ31B magnesium alloy and
nanocomposite using processing map”,Materials & Design, Volume 47, May 2013, Pages 449-455.
P. Ravindran, K. Manisekar, R. Narayanasamy, P. Narayanasamy, “Tribological behaviour of powder metallurgy-
processed aluminium hybrid composites with the addition of graphite solid lubricant”, Ceramics
International, Volume 39, Issue 2, March 2013, Pages 1169-1182.
N. Selvakumar, A.P. Mohan Raj, R. Narayanasamy, “Experimental investigation on workability and strain
hardening behaviour of Fe–C–0.5Mn sintered composites”,Materials & Design, Volume 41, October 2012, Pages
349-357.
M. Sumathi, N. Selvakumar, R. Narayanasamy, “Workability studies on sintered Cu–10SiC preforms during cold
axial upsetting”, Materials & Design, Volume 39, August 2012, Pages 1-8.
P. Ravindran, K. Manisekar, P. Narayanasamy, N. Selvakumar, R. Narayanasamy, “Application of factorial
techniques to study the wear of Al hybrid composites with graphite addition”, Materials & Design, Volume 39,
August 2012, Pages 42-54.
V. Senthilkumar, A. Balaji, R. Narayanasamy, “Analysis of hot deformation behavior of Al 5083–TiC
nanocomposite using constitutive and dynamic material models”, Materials & Design, Volume 37, May 2012,
Pages 102-110.
V.S. Sreenivasan, D. Ravindran, V. Manikandan, R. Narayanasamy, “Influence of fibre treatments on mechanical
properties of short Sansevieria cylindrica/polyester composites”, Materials & Design, Volume 37, May 2012, Pages
111-121.
T. Vigraman, D. Ravindran, R. Narayanasamy, “Effect of phase transformation and intermetallic compounds on
the microstructure and tensile strength properties of diffusion-bonded joints between Ti–6Al–4V and AISI
304L”, Materials & Design, Volume 36, April 2012, Pages 714-727.
74. References cont….
D.R. Kumar, R. Narayanasamy, C. Loganathan, “Effect of Glass and SiC in Aluminum matrix on workability and
strain hardening behavior of powder metallurgy hybrid composites”, Materials & Design, Volume 34, February
2012, Pages 120-136.
M. Srinivasan, C. Loganathan, M. Kamaraj, Q.B. Nguyen, M. Gupta, R. Narayanasamy, “Sliding wear behaviour of
AZ31B magnesium alloy and nano-composite”,Transactions of Nonferrous Metals Society of China, Volume 22,
Issue 1, January 2012, Pages 60-65.
S. Sivasankaran, K. Sivaprasad, R. Narayanasamy, “Microstructure, cold workability and strain hardening
behavior of trimodaled AA 6061–TiO2 nanocomposite prepared by mechanical alloying”, Materials Science and
Engineering: A, Volume 528, Issues 22–23, 25 August 2011, Pages 6776-6787.
S. Sivasankaran, K. Sivaprasad, R. Narayanasamy, P.V. Satyanarayana, “X-ray peak broadening analysis of AA
6061100 − x − x wt.% Al2O3 nanocomposite prepared by mechanical alloying”, Materials Characterization,
Volume 62, Issue 7, July 2011, Pages 661-672.
S. Sivasankaran, K. Sivaprasad, R. Narayanasamy, Vijay Kumar Iyer, “Evaluation of compaction equations and
prediction using adaptive neuro-fuzzy inference system on compressibility behavior of AA 6061100 − x–x wt.%
TiO2 nanocomposites prepared by mechanical alloying”, Powder Technology, Volume 209, Issues 1–3, 15 May 2011,
Pages 124-137.
D.R. Kumar, C. Loganathan, R. Narayanasamy, “Effect of glass in aluminum matrix on workability and strain
hardening behavior of powder metallurgy composite”, Materials & Design, Volume 32, Issue 4, April 2011, Pages
2413-2422.
V.S. Sreenivasan, D. Ravindran, V. Manikandan, R. Narayanasamy, “Mechanical properties of randomly oriented
short Sansevieria cylindrica fibre/polyester composites”, Materials & Design, Volume 32, Issue 4, April 2011, Pages
2444-2455.
M. Srinivasan, C. Loganathan, V. Balasubramanian, Q.B. Nguyen, M. Gupta, R. Narayanasamy, “Feasibility of
joining AZ31B magnesium metal matrix composite by friction welding”, Materials & Design, Volume 32, Issue 3,
March 2011, Pages 1672-1676.
75. References cont….
V.S. Sreenivasan, S. Somasundaram, D. Ravindran, V. Manikandan, R. Narayanasamy, “Microstructural, physico-
chemical and mechanical characterisation of Sansevieria cylindrica fibres – An exploratory investigation”,
Materials & Design, Volume 32, Issue 1, January 2011, Pages 453-461.
S. Sivasankaran, K. Sivaprasad, R. Narayanasamy, Vijay Kumar Iyer, “Effect of strengthening mechanisms on cold
workability and instantaneous strain hardening behavior during grain refinement of AA 6061-10 wt.% TiO2
composite prepared by mechanical alloying”, Journal of Alloys and Compounds, Volume 507, Issue 1, 24
September 2010, Pages 236-244.
S. Sivasankaran, K. Sivaprasad, R. Narayanasamy, Vijay Kumar Iyer, “An investigation on flowability and
compressibility of AA 6061100 − x-x wt.% TiO2 micro and nanocomposite powder prepared by blending and
mechanical alloying”, Powder Technology, Volume 201, Issue 1, 12 July 2010, Pages 70-82.
G. Naveen Kumar, R. Narayanasamy, S. Natarajan, S.P. Kumaresh Babu, K. Sivaprasad, S. Sivasankaran, “Dry sliding
wear behaviour of AA 6351-ZrB2 in situ composite at room temperature”, Materials & Design, Volume 31, Issue 3,
March 2010, Pages 1526-1532.
S. Sivasankaran, K. Sivaprasad, R. Narayanasamy, Vijay Kumar Iyer, “Synthesis, structure and sinterability of 6061
AA100−x–x wt.% TiO2 composites prepared by high-energy ball milling”, Journal of Alloys and Compounds,
Volume 491, Issues 1–2, 18 February 2010, Pages 712-721.
S. Sivasankaran, R. Narayanasamy, T. Ramesh, M. Prabhakar, “Analysis of workability behavior of Al–SiC P/M
composites using backpropagation neural network model and statistical technique”, Computational Materials
Science, Volume 47, Issue 1, November 2009, Pages 46-59.
R. Narayanasamy, V. Anandakrishnan, K.S. Pandey, “Effect of molybdenum addition on workability of powder
metallurgy steels during cold upsetting”, Materials Science and Engineering: A, Volume 517, Issues 1–2, 20 August
2009, Pages 30-36.
S. Natarajan, R. Narayanasamy, S.P. Kumaresh Babu, G. Dinesh, B. Anil Kumar, K. Sivaprasad, “Sliding wear
behaviour of Al 6063/TiB2 in situ composites at elevated temperatures”,Materials & Design, Volume 30, Issue 7,
August 2009, Pages 2521-2531.
76. References cont….
R. Narayanasamy, T. Ramesh, M. Prabhakar, “Effect of particle size of SiC in aluminium matrix on workability
and strain hardening behaviour of P/M composite”, Materials Science and Engineering: A, Volume 504, Issues 1–2,
25 March 2009, Pages 13-23.
K. Sivaprasad, S. P. Kumaresh Babu, S. Natarajan, R. Narayanasamy, B. Anil Kumar, G. Dinesh, “Study on abrasive
and erosive wear behaviour of Al 6063/TiB2 in situ composites”, Materials Science and Engineering: A, Volume
498, Issues 1–2, 20 December 2008, Pages 495-500.
R. Narayanasamy, V. Anandakrishnan, K.S. Pandey, “Effect of carbon content on instantaneous strain-hardening
behaviour of powder metallurgy steels”, Materials Science and Engineering: A, Volume 497, Issues 1–2, 15
December 2008, Pages 505-511.
R. Narayanasamy, V. Anandakrishnan, K.S. Pandey, “Comparison of workability strain and stress parameters of
powder metallurgy steels AISI 9840 and AISI 9845 during cold upsetting”, Materials & Design, Volume 29, Issue
10, December 2008, Pages 1919-1925.
R. Narayanasamy, K. Baskaran, S. Arunachalam, D. Murali Krishna, “An experimental investigation on barreling
of aluminium alloy billets during extrusion forging using different lubricants”, Materials & Design, Volume 29,
Issue 10, December 2008, Pages 2076-2088.
K. Baskaran, R. Narayanasamy, “Effect of various stress ratio parameters on cold upset forging of irregular
shaped billets using graphite as lubricant under plane and triaxial stress state conditions” Materials & Design,
Volume 29, Issue 10, December 2008, Pages 2089-2103.
R. Narayanasamy, V. Anandakrishnan, K.S. Pandey, “Effect of carbon content on workability of powder
metallurgy steels”, Materials Science and Engineering: A, Volume 494, Issues 1–2, 25 October 2008, Pages 337-342.
A.Rajeshkannan, K.S. Pandey, S. Shanmugam, R. Narayanasamy, “Deformation behaviour of sintered high
carbon alloy powder metallurgy steel in powder preform forging”, Materials & Design, Volume 29, Issue 9,
October 2008, Pages 1862-1867.
77. References cont….
R. Ponalagusamy, R. Narayanasamy, “Finite difference method for analysis of open-die forging of sintered
cylindrical billets”, Materials & Design, Volume 29, Issue 9, October 2008, Pages 1886-1892.
A Rajeshkannan, K S Pandey, S Shanmugam, R Narayanasamy, “Sintered Fe-0.8%C-1. 0%Si-0.4%Cu P/M Steel
Preform Behaviour During Cold Upsetting”, Journal of Iron and Steel Research, International, Volume 15, Issue 5,
September 2008, Pages 81-87.
R. Narayanasamy, V. Anandakrishnan, K.S. Pandey, “Effect of geometric work-hardening and matrix work-
hardening on workability and densification of aluminium–3.5% alumina composite during cold
upsetting”,Materials & Design, Volume 29, Issue 8, 2008, Pages 1582-1599.
R. Narayanasamy, K. Baskaran, D. Muralikrishna, “Some studies on stresses and strains of aluminium alloy
during extrusion-forging at room temperature”, Materials & Design, Volume 29, Issue 8, 2008, Pages 1623-1632.
R. Narayanasamy, V. Senthilkumar, K.S. Pandey, “Some features on hot forging of powder metallurgy sintered
high strength 4%titanium carbide composite steel preforms under different stress state conditions”, Materials
& Design, Volume 29, Issue 7, 2008, Pages 1380-1400.
R. Narayanasamy, T. Ramesh, K.S. Pandey, “Some aspects on cold forging of aluminium–alumina powder
metallurgy composite under triaxial stress state condition”, Materials & Design, Volume 29, Issue 6, 2008, Pages
1212-1227.
R. Ponalagusamy, R. Narayanasamy, R. Venkatesan, S. Senthilkumar,“Computer-aided metal flow investigation
in streamlined extrusion dies”, Materials & Design, Volume 29, Issue 6, 2008, Pages 1228-1239.
K. Baskaran, R. Narayanasamy, “An experimental investigation on work hardening behaviour of elliptical
shaped billets of aluminium during cold upsetting”, Materials & Design, Volume 29, Issue 6, 2008, Pages 1240-
1265.
78. References cont….
R. Narayanasamy, T. Ramesh, K.S. Pandey, S.K. Pandey, “Effect of particle size on new constitutive relationship
of aluminium–iron powder metallurgy composite during cold upsetting”,Materials & Design, Volume 29, Issue
5, 2008, Pages 1011-1026.
A. Syed Abu Thaheer, R. Narayanasamy, “Comparison of barreling in lubricated truncated cone billets during
cold upset forging of various metals”,Materials & Design, Volume 29, Issue 5, 2008, Pages 1027-1035.
R. Narayanasamy, T. Ramesh, K.S. Pandey, “Some aspects on cold forging of aluminium–iron powder
metallurgy composite under triaxial stress state condition”, Materials & Design, Volume 29, Issue 4, 2008, Pages
891-903.
K. Baskaran, R. Narayanasamy, “Some aspects of barrelling in elliptical shaped billets of aluminium during
cold upset forging with lubricant”, Materials & Design, Volume 29, Issue 3, 2008, Pages 638-661.
R. Narayanasamy, V. Senthilkumar, K.S. Pandey, “Effect of titanium carbide particle addition on the
densification behavior of sintered P/M high strength steel preforms during cold upset forming”, Materials
Science and Engineering: A, Volume 456, Issues 1–2, 15 May 2007, Pages 180-188.
R. Narayanasamy, T. Ramesh, K.S. Pandey, “An experimental investigation on strain hardening behaviour of
aluminium – 3.5% alumina powder metallurgy composite preform under various stress states during cold
upset forming”, Materials & Design, Volume 28, Issue 4, 2007, Pages 1211-1223.
R. Narayanasamy, N. Selvakumar, K.S. Pandey, “Phenomenon of instantaneous strain hardening behaviour of
sintered Al–Fe composite preforms during cold axial forming”, Materials & Design, Volume 28, Issue 4, 2007,
Pages 1358-1363.
S. Malayappan, R. Narayanasamy, G. Esakkimuthu, “Barrelling of aluminium solid cylinders during cold upset
forging with constraint at both ends”, Materials & Design, Volume 28, Issue 4, 2007, Pages 1404-1411.
79. References cont….
R. Narayanasamy, C. Loganathan, “The influence of friction on the prediction of wrinkling of prestrained
blanks when drawing through a conical die”, Materials & Design, Volume 28, Issue 3, 2007, Pages 904-912.
S. Malayappan, R. Narayanasamy, K. Kalidasamurugavel, “A study on barrelling behaviour of aluminium billets
during cold upsetting with an extrusion die constraint at one end”, Materials & Design, Volume 28, Issue 3, 2007,
Pages 954-961.
A. Syed Abu Thaheer, R. Narayanasamy, “Barrelling in truncated lubricated zinc cone billets during cold upset
forging”, Materials & Design, Volume 28, Issue 2, 2007, Pages 434-440.
K. Manisekar, R. Narayanasamy, “Effect of friction on barrelling in square and rectangular billets of
aluminium during cold upset forging”, Materials & Design, Volume 28, Issue 2, 2007, Pages 592-598.
N. Selvakumar, P. Ganesan, P. Radha, R. Narayanasamy, K.S. Pandey, “Modelling the effect of particle size and
iron content on forming of Al–Fe composite preforms using neural network”, Materials & Design, Volume 28,
Issue 1, 2007, Pages 119-130.
R. Narayanasamy, V. Senthilkumar, K.S. Pandey, “Some aspects of workability studies on hot forging of sintered
high strength 4% titanium carbide composite steel performs”, Materials Science and Engineering: A, Volume 425,
Issues 1–2, 15 June 2006, Pages 121-130.
R. Narayanasamy, V. Senthilkumar, K.S. Pandey, “Some aspects on hot forging features of P/M sintered iron
preforms under various stress state conditions”, Mechanics of Materials, Volume 38, Issue 4, April 2006, Pages
367-386.
R. Narayanasamy, T. Ramesh, K.S. Pandey, “Some aspects on strain hardening behaviour in three dimensions
of aluminium–iron powder metallurgy composite during cold upsetting”, Materials & Design, Volume 27, Issue
8, 2006, Pages 640-650.
80. References cont….
R. Narayanasamy, T. Ramesh, K.S. Pandey, “Workability studies on cold upsetting of Al–Al2O3 composite
material”, Materials & Design, Volume 27, Issue 7, 2006, Pages 566-575.
R. Narayanasamy, R. Ponalagusamy, R. Venkatesan, P. Srinivasan, “An upper bound solution to extrusion of
circular billet to circular shape through cosine dies”, Materials & Design, Volume 27, Issue 5, 2006, Pages 411-415.
K. Manisekar, R. Narayanasamy, S. Malayappan, “Effect of friction on barrelling in square billets of aluminium
during cold upset forging”, Materials & Design, Volume 27, Issue 2, 2006, Pages 147-155.
R. Ponalagusamy, R. Narayanasamy, P. Srinivasan, “Design and development of streamlined extrusion dies a
Bezier curve approach”, Journal of Materials Processing Technology, Volume 161, Issue 3, 30 April 2005, Pages 375-
380.
R. Narayanasamy, T. Ramesh, K.S. Pandey , “An investigation on instantaneous strain hardening behaviour in
three dimensions of aluminium–iron composites during cold upsetting”, Materials Science and Engineering: A,
Volume 394, Issues 1–2, 15 March 2005, Pages 149-160.
R. Narayanasamy, T. Ramesh, K.S. Pandey, “Some aspects on workability of aluminium–iron powder
metallurgy composite during cold upsetting”, Materials Science and Engineering: A, Volume 391, Issues 1–2, 25
January 2005, Pages 418-426.
N Selvakumar, R Narayanasamy, “Phenomenon of strain hardening behaviour of sintered aluminium
preforms during cold axial forming”, Journal of Materials Processing Technology, Volume 142, Issue 2, 25 November
2003, Pages 347-354.
R Narayanasamy, P Srinivasan, R Venkatesan, “Computer aided design and manufacture of streamlined
extrusion dies”, Journal of Materials Processing Technology, Volume 138, Issues 1–3, 20 July 2003, Pages 262-264.
81. References cont….
S. Malayappan, R. Narayanasamy, “Some aspects on barrelling in aluminium solid cylinders during cold upset
forging using a die with constraints”, Journal of Materials Processing Technology, Volume 135, Issue 1, 1 April 2003,
Pages 18-29.
R. Narayanasamy, R. Ponalagusamy, K.R. Subramanian, “Generalised yield criteria of porous sintered powder
metallurgy metals”, Journal of Materials Processing Technology, Volume 110, Issue 2, 19 March 2001, Pages 182-185.
R Narayanasamy, S Sathiyanarayanan, R Ponalagusamy, “Uniaxial tensile behaviour of ZM-21 magnesium alloy at
room temperature”, Journal of Materials Processing Technology, Volume 102, Issues 1–3, 15 May 2000, Pages 56-58.
R Narayanasamy, S Sathiyanarayanan, R Ponalagusamy, “A study on barrelling in magnesium alloy solid
cylinders during cold upset forming”, Journal of Materials Processing Technology, Volume 101, Issues 1–3, 14 April
2000, Pages 64-69.
R Narayanasamy, K.S Pandey, “A study on the barrelling of sintered iron preforms during hot upset forging”,
Journal of Materials Processing Technology, Volume 100, Issues 1–3, 3 April 2000, Pages 87-94.
R. Narayanasamy, R. Ponalagusamy, “A mathematical theory of plasticity for compressible powder metallurgy
materials — Part III”, Journal of Materials Processing Technology, Volume 100, Issues 1–3, 3 April 2000, Pages 262-
265.
R Narayanasamy, R Ponalagusamy, “A mathematical theory of plasticity for the upsetting of compressible P/M
materials”, Journal of Materials Processing Technology, Volume 97, Issues 1–3, 1 January 2000, Pages 107-109.
R. Narayanasamy, R. Ponalagusamy, “A mathematical theory of plasticity for compressible powder metallurgy
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