This lecture gives a brief review of the fundamental terms and laws governing metal forming at room temperature as well as at high temperatures. This lecture is a necessary prerequisite to understand the more specific treatment of metal forming subjects such as forging, impact extrusion and sheet metal forming in the subsequent TALAT This lectures 3400 to 3800. General background in production engineering, machine tools is assumed.
This document discusses rolling processes used to shape metals. It describes rolling as a bulk deformation process that reduces thickness or changes cross-section of a workpiece using compressive forces from rotating rolls. Hot rolling involves heating metal above its recrystallization temperature before rolling, allowing larger deformation and grain refinement. Cold rolling increases strength but reduces ductility, so heat treatment is often required after. The document provides details on advantages and limitations of both hot and cold rolling processes.
Heat treatment involves heating and cooling metals to alter their internal structure and properties. There are several heat treatment methods for carbon steels including annealing, normalizing, hardening, and tempering. Annealing involves heating steel to high temperatures and slowly cooling to relieve stresses and improve ductility. Normalizing also starts with heating above the critical point but involves air cooling to refine grain size. Hardening greatly increases hardness but causes brittleness, so tempering is used to relieve stresses and improve toughness through controlled reheating.
This document provides an overview of metal forging processes. It begins with an introduction to forging and then classifies forging processes into hammer/drop forging and press forging. It further classifies processes as open-die forging or closed-die forging. The document also discusses typical forging operations, the types of forging machines, and provides examples of specific forging processes. It describes the goals of minimizing forging defects and achieving the desired final shape and properties of forged parts.
Extrusion is a process that uses pressure to force heated metal material through a die to create parts with a constant cross-section. There are two main types of extrusion: direct and indirect. Direct extrusion involves pushing the material through the die in the same direction as the ram movement, while indirect extrusion moves the material in the opposite direction of the ram. Extrusion can be performed hot or cold depending on the material, with hot extrusion allowing for more complex shapes from more readily extrudable metals like aluminum. Proper die material and lubrication are important for reducing friction during extrusion.
The document discusses various heat treatment processes including annealing, normalizing, quenching, and martensitic transformation. It provides details on the purposes, methods, and applications of each process. Annealing involves heating and slow cooling to relieve stresses and modify properties. Normalizing heats above the transformation temperature and air cools to produce a fine grain structure. Quenching rapidly cools steel above the transformation temperature to form very hard martensite. Martensitic transformation is the formation of acicular needlelike structures during rapid cooling of austenite.
This document provides an overview of fatigue failure. It begins by defining fatigue as the premature failure or lowering of strength of a material due to repetitive stresses, even if they are below the material's yield strength. It then discusses key topics in fatigue such as stress cycles, S-N curves, fatigue testing, and factors that affect fatigue life. Crack initiation and propagation stages are described. Methods for improving fatigue performance, such as shot peening and removing stress concentrators, are also covered.
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.
Defects in deep drawing and their remediesShivam Pandey
This document discusses common defects that can occur in the deep drawing process and their remedies. It describes defects such as flange wrinkles, step rings, draw marks, orange peel, scratches, fractured flanges and bottoms, corner fractures, miss strikes, and directional earing. For each defect, it provides details on what causes the defect and potential remedies, such as increasing the blank holder force, using a draw bead, ensuring proper lubrication and die surface finish, working within material limits, and providing sufficient blank holder force. The overall document serves as a guide for identifying and addressing issues that may arise during the deep drawing manufacturing process.
This document discusses rolling processes used to shape metals. It describes rolling as a bulk deformation process that reduces thickness or changes cross-section of a workpiece using compressive forces from rotating rolls. Hot rolling involves heating metal above its recrystallization temperature before rolling, allowing larger deformation and grain refinement. Cold rolling increases strength but reduces ductility, so heat treatment is often required after. The document provides details on advantages and limitations of both hot and cold rolling processes.
Heat treatment involves heating and cooling metals to alter their internal structure and properties. There are several heat treatment methods for carbon steels including annealing, normalizing, hardening, and tempering. Annealing involves heating steel to high temperatures and slowly cooling to relieve stresses and improve ductility. Normalizing also starts with heating above the critical point but involves air cooling to refine grain size. Hardening greatly increases hardness but causes brittleness, so tempering is used to relieve stresses and improve toughness through controlled reheating.
This document provides an overview of metal forging processes. It begins with an introduction to forging and then classifies forging processes into hammer/drop forging and press forging. It further classifies processes as open-die forging or closed-die forging. The document also discusses typical forging operations, the types of forging machines, and provides examples of specific forging processes. It describes the goals of minimizing forging defects and achieving the desired final shape and properties of forged parts.
Extrusion is a process that uses pressure to force heated metal material through a die to create parts with a constant cross-section. There are two main types of extrusion: direct and indirect. Direct extrusion involves pushing the material through the die in the same direction as the ram movement, while indirect extrusion moves the material in the opposite direction of the ram. Extrusion can be performed hot or cold depending on the material, with hot extrusion allowing for more complex shapes from more readily extrudable metals like aluminum. Proper die material and lubrication are important for reducing friction during extrusion.
The document discusses various heat treatment processes including annealing, normalizing, quenching, and martensitic transformation. It provides details on the purposes, methods, and applications of each process. Annealing involves heating and slow cooling to relieve stresses and modify properties. Normalizing heats above the transformation temperature and air cools to produce a fine grain structure. Quenching rapidly cools steel above the transformation temperature to form very hard martensite. Martensitic transformation is the formation of acicular needlelike structures during rapid cooling of austenite.
This document provides an overview of fatigue failure. It begins by defining fatigue as the premature failure or lowering of strength of a material due to repetitive stresses, even if they are below the material's yield strength. It then discusses key topics in fatigue such as stress cycles, S-N curves, fatigue testing, and factors that affect fatigue life. Crack initiation and propagation stages are described. Methods for improving fatigue performance, such as shot peening and removing stress concentrators, are also covered.
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.
Defects in deep drawing and their remediesShivam Pandey
This document discusses common defects that can occur in the deep drawing process and their remedies. It describes defects such as flange wrinkles, step rings, draw marks, orange peel, scratches, fractured flanges and bottoms, corner fractures, miss strikes, and directional earing. For each defect, it provides details on what causes the defect and potential remedies, such as increasing the blank holder force, using a draw bead, ensuring proper lubrication and die surface finish, working within material limits, and providing sufficient blank holder force. The overall document serves as a guide for identifying and addressing issues that may arise during the deep drawing manufacturing process.
Deep drawing is a metal forming process where a sheet metal blank is placed over a die opening and forced into the die cavity by a punch. It is commonly used to make cylindrical or box-shaped parts like pots, pans, and automotive fuel tanks. Metals used include alloys, aluminum, brass, cold rolled steel, and copper. Lubrication is applied to reduce forces and increase formability.
The document provides an overview of the wire drawing process. It discusses how wire drawing works by pulling a wire through progressively smaller dies to reduce its diameter and increase its length. This cold working process improves the material properties of the wire. Key aspects covered include the types of drawing, processing parameters like die design and lubrication, how drawing machines operate using multiple dies, and common die materials like cemented carbides and industrial diamonds.
This document summarizes key concepts regarding fatigue crack propagation. It discusses three stages of crack growth: (1) crack initiation, where microcracks form due to cyclic stresses; (2) crack propagation, where cracks grow according to Paris' law and form fatigue striations; and (3) final failure, where cracks rapidly grow unstable until catastrophic fracture. Critical factors like stress levels, number of cycles, and material properties are outlined. Paris' law and sigmoidal crack growth curves are also summarized.
This document discusses fatigue failure in metals. It defines fatigue as weakness caused by repeated cyclic loading. There are two types of fatigue loading: low-cycle loading with high stresses that cause plastic deformation, and high-cycle loading with lower elastic stresses. Fatigue failure requires sufficient tensile stresses, stress variations through cycling, and a large number of cycles. The document outlines fatigue testing methods, the stages of fatigue propagation including crack initiation and propagation, analyzing fatigue failures, and methods for preventing fatigue such as surface treatments and removing stress concentrators.
This document discusses various metal forming rolling processes. It defines rolling as plastically deforming metal by passing it between rolls. There are different types of rolling processes including transverse, shaped, skew, ring, thread, tube, powder, and continuous casting and hot rolling. It also describes the classification and purposes of processes like transverse, shaped, skew, ring, thread, and tube rolling. Finally, it discusses sheet rolling processes including hot and cold rolling.
This document discusses various types of forging processes including hot forging, press forging, swaging, and cold forging. It describes how each process uses compressive forces and dies to shape metal at different temperatures. Examples of specific forging techniques are provided like hammer forging, drop forging, and upset forging. The document also outlines common forging tools, defects that may occur, and applications in small tools and automotive manufacturing.
This document discusses creep, which is the time-dependent plastic deformation of materials under constant stress that is below their yield strength. It occurs more at higher temperatures, especially above 35% of the melting point for metals. Creep testing involves applying a constant stress and measuring strain over time. The resulting creep curve shows three stages: primary, secondary, and tertiary creep. Creep is influenced by mechanisms like dislocation climb, vacancy diffusion, and grain boundary sliding. Creep can be reduced by using high-melting point alloys, coarse grains, precipitation hardening, and dispersion strengthening. Creep is an important consideration in designing components that operate at high temperatures, such as turbine blades and steam pipes.
This document discusses various metal fabrication processes and heat treatments. The main metal fabrication processes covered are cutting, folding, punching, shearing, welding, forging, rolling, extrusion and drawing. Common raw materials used include plate metal, tube stock, welding wire, castings and fittings. Annealing heat treatments are also summarized, which involve heating metal to high temperatures to relieve stresses, increase softness and ductility, and produce desired microstructures, followed by controlled cooling. The stages of annealing and different types of annealing like normalizing and full annealing are defined.
The document provides information on various casting processes for aluminum alloys. It discusses sand casting, die casting, semi-solid casting, squeeze casting, and Cosworth casting. For each process, it describes the key steps, suitability for different applications, advantages, and disadvantages. Sand casting allows for complex shapes at low cost but has rough finishes. Die casting facilitates high-volume production of parts with complex geometries. Semi-solid casting results in near-net shape parts with excellent dimensional accuracy. Squeeze casting produces stronger parts with a tighter grain structure.
Metal forming processes are used to shape metals into useful products. Rolling is the most common forming process and accounts for around 90% of metal forming. It involves passing metal between rolls to reduce thickness or change cross-section. Forging uses dies and compression to shape hot or cold metal. Extrusion forces heated metal through a die to create shapes like rods, tubes and structural sections. Drawing pulls metal through a die to make wires, rods and tubes from both hot and cold workpieces. Deep drawing specifically makes cylindrical parts like cups from sheet metal.
The document discusses various aspects of metal forming processes including strain hardening, work hardening, annealing, cold working, hot working, and the effects of temperature and strain rate on formability.
Some key points include: Strain hardening occurs during metal forming at lower temperatures and increases flow stress. Work hardening is caused by an increase in dislocation density during plastic deformation. Annealing heat treats cold worked metals to restore ductility by reducing dislocation density. Cold working is done below the recrystallization temperature and causes strain hardening, while hot working allows recrystallization during forming. Temperature and strain rate impact formability, with higher temperatures and lower strain rates generally improving formability.
This document discusses sheet metal forming processes. It introduces various sheet metal forming methods like bending, stretching, deep drawing, and identifies common defects. The objectives are to describe sheet metal forming processes, discuss variables that affect formability, and emphasize defects and solutions. Various forming equipment, stresses involved, and classifications of sheet metal parts and processes are outlined over several pages.
Bulk metal forming processes change the shape of metal parts through plastic deformation. Hot working above the metal's recrystallization temperature allows for significant shape changes with less force. Cold working below this temperature increases strength but requires more force. Common bulk metal forming processes include forging, rolling, and extrusion, which can produce parts near their final net shape with little waste.
Stainless steels contain 10.5-30% chromium which forms a passive oxide layer protecting the steel from corrosion. Common types include martensitic, ferritic, austenitic, and duplex stainless steels. Martensitic stainless steels can be hardened through heat treatment while ferritic stainless steels have higher ductility and corrosion resistance. Duplex stainless steels have a mixed austenite and ferrite structure providing high strength and pitting/stress corrosion resistance. Austenitic stainless steels have excellent ductility and toughness down to cryogenic temperatures and are widely used in chemical plants and food processing. Proper welding techniques are required to prevent issues like sensitization, hot cracking, and sigma
This document discusses various carbon and alloy steels. It begins by classifying steels based on their carbon content as plain carbon steels including low carbon (<0.3%), medium carbon (0.3-0.6%) and high carbon (0.6-0.95%). Alloy steels are then introduced which add other elements to iron to improve properties. The AISI classification system is explained which uses a 4 digit numbering system relating to steel composition. Examples of common carbon and alloy steels are given. Heat treating processes like annealing, normalizing and quenching+tempering are defined in terms of their effects on microstructure and properties. Specific alloying elements used in steels like manganese,
Introduction Hot Working and Cold Working of Metals Forging Processes- Open, impression die forging, Closed die forging-forging operation Rolling of metals-types of rolling- Flat strip rolling-shape rolling operation -Defects in rolled parts- Principle of rod and wire drawing-tube drawing -Principle of extrusion Types-hot and cold extrusion.
The document provides information on various types of building and construction materials including:
- Mild steel grades such as S235 JR and their mechanical properties.
- Cold rolled steel grade DC01 and its surface finishes.
- Galvanized steels with specifications for coatings like G60 and qualities like DX51D.
- Stainless steels grades 304 and 316 and their mechanical properties.
- Aluminum alloys 5052 and 6063 with conversion tables.
- Guidelines for bi-metallic contact between different metals.
- Hot-dip galvanization process and comparisons of standards like ISO 1461 and ASTM A123 for coating thickness.
Blackodising is a process that forms a corrosion-resistant coating on ferrous metals through a chemical reaction when immersed in a hot alkaline salt solution. This reaction converts the metal surface into magnetite (Fe3O4), providing protection without changing the part's dimensions. The black oxide coating has various applications and advantages, including corrosion resistance, an aesthetic black finish, and low cost processing, making it suitable for tool parts, fixtures, gears, and other mechanical components.
1. The document discusses the Schaeffler diagram, which is used to predict the microstructure of stainless steel welds based on their composition. It also discusses modifications to the diagram by Delong.
2. The M3 concept for developing third generation advanced high strength steels is described, which aims to achieve ultrahigh strength and ductility through a multi-phase, meta-stable, multi-scale microstructure.
3. Quenching and partitioning heat treatments are summarized as a novel method to produce multi-phase steels with significant retained austenite through quenching to form martensite and austenite, followed by an isothermal treatment to partition carbon into the a
The document discusses various sheet metalworking processes including cutting, bending, and drawing. Cutting operations like shearing, blanking, and punching are used to cut sheet metal. Bending involves straining sheet metal around a straight axis using methods like V-bending and edge bending. Drawing forms sheet metal into convex or concave shapes. Key considerations in sheet metalworking are clearance, bending allowances, springback, and forces required for cutting.
The document discusses the use of electron channeling contrast imaging (ECCI) to characterize deformation mechanisms in twinning-induced plasticity (TWIP) steels. ECCI allows dislocations and twins to be imaged at high resolution in a scanning electron microscope under controlled diffraction conditions. ECCI reveals the formation of dislocation cells and mechanical twins during deformation. Different grain types in TWIP steels are identified that deform through slip and twinning to different extents, influencing work hardening.
This document summarizes research on the hot deformation behavior of a twinning induced plasticity (TWIP) steel containing 20% manganese. Hot compression tests were performed at temperatures from 800-1200°C and strain rates from 0.001-0.1 s-1. The steel exhibited high strength over 1000 MPa and ductility over 55% at room temperature due to twinning. Flow curves showed stress increased with lower temperatures and higher strain rates. Microstructures indicated dynamic recrystallization was slow. Double hit compression tests at 900°C showed static recrystallization kinetics were also relatively slow, with over 70% recrystallization after 50-100 seconds. The results provide important insights for controlling hot working
Deep drawing is a metal forming process where a sheet metal blank is placed over a die opening and forced into the die cavity by a punch. It is commonly used to make cylindrical or box-shaped parts like pots, pans, and automotive fuel tanks. Metals used include alloys, aluminum, brass, cold rolled steel, and copper. Lubrication is applied to reduce forces and increase formability.
The document provides an overview of the wire drawing process. It discusses how wire drawing works by pulling a wire through progressively smaller dies to reduce its diameter and increase its length. This cold working process improves the material properties of the wire. Key aspects covered include the types of drawing, processing parameters like die design and lubrication, how drawing machines operate using multiple dies, and common die materials like cemented carbides and industrial diamonds.
This document summarizes key concepts regarding fatigue crack propagation. It discusses three stages of crack growth: (1) crack initiation, where microcracks form due to cyclic stresses; (2) crack propagation, where cracks grow according to Paris' law and form fatigue striations; and (3) final failure, where cracks rapidly grow unstable until catastrophic fracture. Critical factors like stress levels, number of cycles, and material properties are outlined. Paris' law and sigmoidal crack growth curves are also summarized.
This document discusses fatigue failure in metals. It defines fatigue as weakness caused by repeated cyclic loading. There are two types of fatigue loading: low-cycle loading with high stresses that cause plastic deformation, and high-cycle loading with lower elastic stresses. Fatigue failure requires sufficient tensile stresses, stress variations through cycling, and a large number of cycles. The document outlines fatigue testing methods, the stages of fatigue propagation including crack initiation and propagation, analyzing fatigue failures, and methods for preventing fatigue such as surface treatments and removing stress concentrators.
This document discusses various metal forming rolling processes. It defines rolling as plastically deforming metal by passing it between rolls. There are different types of rolling processes including transverse, shaped, skew, ring, thread, tube, powder, and continuous casting and hot rolling. It also describes the classification and purposes of processes like transverse, shaped, skew, ring, thread, and tube rolling. Finally, it discusses sheet rolling processes including hot and cold rolling.
This document discusses various types of forging processes including hot forging, press forging, swaging, and cold forging. It describes how each process uses compressive forces and dies to shape metal at different temperatures. Examples of specific forging techniques are provided like hammer forging, drop forging, and upset forging. The document also outlines common forging tools, defects that may occur, and applications in small tools and automotive manufacturing.
This document discusses creep, which is the time-dependent plastic deformation of materials under constant stress that is below their yield strength. It occurs more at higher temperatures, especially above 35% of the melting point for metals. Creep testing involves applying a constant stress and measuring strain over time. The resulting creep curve shows three stages: primary, secondary, and tertiary creep. Creep is influenced by mechanisms like dislocation climb, vacancy diffusion, and grain boundary sliding. Creep can be reduced by using high-melting point alloys, coarse grains, precipitation hardening, and dispersion strengthening. Creep is an important consideration in designing components that operate at high temperatures, such as turbine blades and steam pipes.
This document discusses various metal fabrication processes and heat treatments. The main metal fabrication processes covered are cutting, folding, punching, shearing, welding, forging, rolling, extrusion and drawing. Common raw materials used include plate metal, tube stock, welding wire, castings and fittings. Annealing heat treatments are also summarized, which involve heating metal to high temperatures to relieve stresses, increase softness and ductility, and produce desired microstructures, followed by controlled cooling. The stages of annealing and different types of annealing like normalizing and full annealing are defined.
The document provides information on various casting processes for aluminum alloys. It discusses sand casting, die casting, semi-solid casting, squeeze casting, and Cosworth casting. For each process, it describes the key steps, suitability for different applications, advantages, and disadvantages. Sand casting allows for complex shapes at low cost but has rough finishes. Die casting facilitates high-volume production of parts with complex geometries. Semi-solid casting results in near-net shape parts with excellent dimensional accuracy. Squeeze casting produces stronger parts with a tighter grain structure.
Metal forming processes are used to shape metals into useful products. Rolling is the most common forming process and accounts for around 90% of metal forming. It involves passing metal between rolls to reduce thickness or change cross-section. Forging uses dies and compression to shape hot or cold metal. Extrusion forces heated metal through a die to create shapes like rods, tubes and structural sections. Drawing pulls metal through a die to make wires, rods and tubes from both hot and cold workpieces. Deep drawing specifically makes cylindrical parts like cups from sheet metal.
The document discusses various aspects of metal forming processes including strain hardening, work hardening, annealing, cold working, hot working, and the effects of temperature and strain rate on formability.
Some key points include: Strain hardening occurs during metal forming at lower temperatures and increases flow stress. Work hardening is caused by an increase in dislocation density during plastic deformation. Annealing heat treats cold worked metals to restore ductility by reducing dislocation density. Cold working is done below the recrystallization temperature and causes strain hardening, while hot working allows recrystallization during forming. Temperature and strain rate impact formability, with higher temperatures and lower strain rates generally improving formability.
This document discusses sheet metal forming processes. It introduces various sheet metal forming methods like bending, stretching, deep drawing, and identifies common defects. The objectives are to describe sheet metal forming processes, discuss variables that affect formability, and emphasize defects and solutions. Various forming equipment, stresses involved, and classifications of sheet metal parts and processes are outlined over several pages.
Bulk metal forming processes change the shape of metal parts through plastic deformation. Hot working above the metal's recrystallization temperature allows for significant shape changes with less force. Cold working below this temperature increases strength but requires more force. Common bulk metal forming processes include forging, rolling, and extrusion, which can produce parts near their final net shape with little waste.
Stainless steels contain 10.5-30% chromium which forms a passive oxide layer protecting the steel from corrosion. Common types include martensitic, ferritic, austenitic, and duplex stainless steels. Martensitic stainless steels can be hardened through heat treatment while ferritic stainless steels have higher ductility and corrosion resistance. Duplex stainless steels have a mixed austenite and ferrite structure providing high strength and pitting/stress corrosion resistance. Austenitic stainless steels have excellent ductility and toughness down to cryogenic temperatures and are widely used in chemical plants and food processing. Proper welding techniques are required to prevent issues like sensitization, hot cracking, and sigma
This document discusses various carbon and alloy steels. It begins by classifying steels based on their carbon content as plain carbon steels including low carbon (<0.3%), medium carbon (0.3-0.6%) and high carbon (0.6-0.95%). Alloy steels are then introduced which add other elements to iron to improve properties. The AISI classification system is explained which uses a 4 digit numbering system relating to steel composition. Examples of common carbon and alloy steels are given. Heat treating processes like annealing, normalizing and quenching+tempering are defined in terms of their effects on microstructure and properties. Specific alloying elements used in steels like manganese,
Introduction Hot Working and Cold Working of Metals Forging Processes- Open, impression die forging, Closed die forging-forging operation Rolling of metals-types of rolling- Flat strip rolling-shape rolling operation -Defects in rolled parts- Principle of rod and wire drawing-tube drawing -Principle of extrusion Types-hot and cold extrusion.
The document provides information on various types of building and construction materials including:
- Mild steel grades such as S235 JR and their mechanical properties.
- Cold rolled steel grade DC01 and its surface finishes.
- Galvanized steels with specifications for coatings like G60 and qualities like DX51D.
- Stainless steels grades 304 and 316 and their mechanical properties.
- Aluminum alloys 5052 and 6063 with conversion tables.
- Guidelines for bi-metallic contact between different metals.
- Hot-dip galvanization process and comparisons of standards like ISO 1461 and ASTM A123 for coating thickness.
Blackodising is a process that forms a corrosion-resistant coating on ferrous metals through a chemical reaction when immersed in a hot alkaline salt solution. This reaction converts the metal surface into magnetite (Fe3O4), providing protection without changing the part's dimensions. The black oxide coating has various applications and advantages, including corrosion resistance, an aesthetic black finish, and low cost processing, making it suitable for tool parts, fixtures, gears, and other mechanical components.
1. The document discusses the Schaeffler diagram, which is used to predict the microstructure of stainless steel welds based on their composition. It also discusses modifications to the diagram by Delong.
2. The M3 concept for developing third generation advanced high strength steels is described, which aims to achieve ultrahigh strength and ductility through a multi-phase, meta-stable, multi-scale microstructure.
3. Quenching and partitioning heat treatments are summarized as a novel method to produce multi-phase steels with significant retained austenite through quenching to form martensite and austenite, followed by an isothermal treatment to partition carbon into the a
The document discusses various sheet metalworking processes including cutting, bending, and drawing. Cutting operations like shearing, blanking, and punching are used to cut sheet metal. Bending involves straining sheet metal around a straight axis using methods like V-bending and edge bending. Drawing forms sheet metal into convex or concave shapes. Key considerations in sheet metalworking are clearance, bending allowances, springback, and forces required for cutting.
The document discusses the use of electron channeling contrast imaging (ECCI) to characterize deformation mechanisms in twinning-induced plasticity (TWIP) steels. ECCI allows dislocations and twins to be imaged at high resolution in a scanning electron microscope under controlled diffraction conditions. ECCI reveals the formation of dislocation cells and mechanical twins during deformation. Different grain types in TWIP steels are identified that deform through slip and twinning to different extents, influencing work hardening.
This document summarizes research on the hot deformation behavior of a twinning induced plasticity (TWIP) steel containing 20% manganese. Hot compression tests were performed at temperatures from 800-1200°C and strain rates from 0.001-0.1 s-1. The steel exhibited high strength over 1000 MPa and ductility over 55% at room temperature due to twinning. Flow curves showed stress increased with lower temperatures and higher strain rates. Microstructures indicated dynamic recrystallization was slow. Double hit compression tests at 900°C showed static recrystallization kinetics were also relatively slow, with over 70% recrystallization after 50-100 seconds. The results provide important insights for controlling hot working
The document is the midterm examination for an introduction to software engineering course. It contains instructions for the exam, which has multiple choice and essay questions. Students are to write their name, ID, and signature on the cover page and top of the exam booklet. The exam is closed book and has a duration of 75 minutes.
This document contains a mid-term examination question paper for Class VI from Fazia Schools & Colleges. The paper tests students on their knowledge of mathematics, computer science, and English. It includes multiple choice and short answer questions assessing topics like sets, numbers, computers, grammar, and literature comprehension. The exam is divided into three sections and covers areas of the curriculum for these subjects at the sixth grade level.
This document provides an overview of metal forming processes, including definitions, classifications, and comparisons of hot and cold working. It discusses key topics such as plastic deformation, strain hardening, yield criteria, temperature effects, lubrication, and considerations in process selection. The objectives are to understand elastic and plastic deformation, strain hardening concepts, yield criteria, and differences between hot and cold working processes.
The document discusses metal forming processes. It describes bulk deformation processes like rolling, forging, extrusion, and wire/bar drawing which use plastic deformation to change the shape of metal workpieces. These processes apply stresses that exceed the metal's yield strength. The document outlines factors that influence metal forming like material properties, temperature, friction, and lubrication. It provides an overview of different forming techniques and their characteristics.
The document provides information on impact extrusion processes, including definitions, classifications, process steps, and material flow and deformation characteristics. Impact extrusion involves pressing a workpiece through a die opening using a punch. There are different classifications based on tool type, material flow direction, workpiece geometry, and temperature. Key process variations include solid and hollow, forward and backward extrusion. Material flow is initially non-stationary but transitions to quasi-stationary. Strain is highest near the die opening and decreases radially. Punch and die designs impact stresses and mandrel movement.
This lecture describes the fundamentals of bending and folding aluminium sheet; it also describes different methods in design of folding tools. Background in production engineering and sheet metal forming and familiarity with the subject matter covered in TALAT This lectures 3701- 3705 is assumed.
The document discusses various metal forming processes including rolling, extrusion, and forging. It describes rolling as reducing the cross-sectional area of metal by passing it through a pair of rotating rolls. Extrusion shapes metal by forcing a billet through a die opening, and can be direct or indirect. The document provides detailed information on rolling processes like flat rolling, shape rolling, thread rolling, and ring rolling, and the various types of rolling mills used.
This document provides an overview of continuous casting of aluminium, specifically focusing on strip casting and wire bar casting technologies. It describes the basic principles of continuous casting, including key features like using rotating drums or belts to form a mould for molten aluminium. It discusses different types of casters like twin drum casters, single drum casters, and those using belts or blocks. It also addresses properties of continuously cast products and their behavior in further processing like rolling. The document aims to give readers an understanding of the possibilities and limitations of continuous casting aluminium.
This document provides an overview of sheet metal forming processes. It discusses both cutting (shearing) operations like punching, blanking, and notching as well as forming operations like bending, drawing, squeezing, and hydroforming. The document describes various bending operations including V-bending, roll bending, and tube bending. It also discusses processes for forming parts like deep drawing, ironing, redrawing, and the multi-step metal forming process used to produce aluminum beverage cans.
This lecture gives a brief introduction into the basic fabrication methods for structural aluminium alloy materials with respect to machining, forming, joining and surface treatments as a necessary background for the design process; it describes the subject of welding structural aluminium alloys in order to understand the materials requirements which the designer has to take into account when designing load carrying welded aluminium structures. General materials engineering background is assumed.
In general, aluminium alloys have excellent machining properties compared with other common engineering metals.The lecture describes the machinability of aluminium alloys, the necessary tools and equipments in order to obtain optimum results. General background in production engineering and machine tools is assumed.
IRJET- Theoretical Study of Tooling Systems and Parametric Optimization of Tu...IRJET Journal
This document presents a theoretical study of tooling systems and parametric optimization for turning stainless steel using a carbide tool. The study aims to understand the optimal settings for cutting parameters like speed, feed rate, and depth of cut to minimize machining forces. Experiments were conducted on a lathe to measure forces with a dynamometer under wet machining conditions. The Taguchi method was used for analysis and MINITAB for statistical confirmation. A literature review covered topics like surface roughness in microturning titanium alloys, micro machining force models, ductile regime machining of silicon nitride, and models for built-up edge formation.
This industrial training report discusses single minute exchange of die (SMED) in closed die forging. It provides an overview of Good Luck Engineering Co., which manufactures open and closed die steel forgings. The report describes the forging process, including cold forging, warm forging, and hot forging. It also discusses closed die forging and open die forging techniques and the key steps in the forging process, including die preparation, lubrication, and multi-step forming. The goal of the report is to analyze SMED techniques that can reduce die changeover times in closed die forging.
This lecture describes fabrication processes for superplastic forming, i.e. female and male die forming, and the criteria for selecting the correct process. General background in production engineering and material science is assumed.
This lecture helps to understand the basic principles of die forging and the characteristic features of special aluminium die forging processes. It aims at learning about the basic design of dies in order to obtain optimum part qualities and tool life. General understanding of metallurgy and deformation processes is assumed.
This lecture gives definition and explanation of terms; it teaches the most important fundamental laws governing deep drawing; it explains special considerations for deep drawing of aluminium sheet metal. Background in production engineering and familiarity with the subject matter covered in TALAT This lecture 3701 is assumed.
Sheet metal processes involve cutting, bending, and drawing operations. Shearing is the primary cutting operation used to cut sheet metal blanks from large sheets. It involves using a punch and die to cut along a straight line. Bending forms sheet metal by curving it around a straight axis and is done using V-bending or edge bending. Both cutting and bending can result in springback as the sheet tries to return to its original shape after forming. Process parameters like punch and die design, clearance, and lubrication affect the quality of cuts and bends in sheet metal fabrication.
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TALAT Lecture 3300: Fundamentals of Metal Forming
1. TALAT Lecture 3300
Fundamentals of Metal Forming
18 pages, 27 figures
Basic Level
prepared by Klaus Siegert and Eckart Dannenmann, Institut für Umformtechnik,
Universität Stuttgart
Objectives:
− a brief review of the fundamental terms and laws governing metal forming at
room temperature as well as at high temperatures. This lecture is a necessary
prerequisite to understand the more specific treatment of metal forming
subjects such as forging, impact extrusion and sheet metal forming in the
subsequent TALAT Lectures 3400 to 3800.
Prerequisites:
− General background in production engineering, machine tools
Date of Issue: 1996
EAA - European Aluminium Association
2. 3300 Fundamentals of Metal Forming
Table of Contents
3300 Fundamentals of Metal Forming ............................................................2
3301 Introduction................................................................................................... 3
3301.01 Definition of Forming ..............................................................................3
3302 Terms for Classifying Forming Processes .................................................. 4
3302.01 Classification by State of Stress (Figure 3302.01.01)..............................4
3302.02 Classification by Type of Raw Material (Figure 3302.02.01) .................4
3302.03 Classification by Forming Temperature...................................................5
3302.04 Classification by Methods of Induction of Forces into the Work-Piece..5
3303 Characteristic Values and Basic Laws of Metal Forming......................... 6
3303.01 Flow Stress...............................................................................................6
3303.02 Plastic Strain, Rate and Acceleration.......................................................7
Logarithmic (True) Plastic Strain....................................................................... 7
Logarithmic Strain in Upsetting ......................................................................... 7
Law of Volume Constancy .................................................................................. 8
Plastic Strain Rate .............................................................................................. 8
Plastic Strain Acceleration ................................................................................. 9
3303.03 Plastic Flow under Combined Stresses ....................................................9
Criteria for Plastic Flow..................................................................................... 9
Maximum Shear Stress Hypothesis................................................................... 10
Mises Flow Criterion ........................................................................................ 11
Yield Criteria for Plane Stress (Yield Locus) ................................................... 12
3303.04 Law of Plastic Flow ...............................................................................12
3303.05 Flow Curves .............................................................................................13
General Definition of the Flow Curve .............................................................. 13
Flow Curves at Room Temperature.................................................................. 13
Flow Curves at Elevated Temperatures............................................................ 14
3303.06 Average Flow Stress ..............................................................................16
3303.07 Energy Considerations ...........................................................................16
Forming Energy ................................................................................................ 16
Heat Development during Forming .................................................................. 17
Literature/References ............................................................................................. 18
List of Figures.......................................................................................................... 18
TALAT 3300 2
3. 3301 Introduction
3301.01 Definition of Forming
The general description given in Figure 3301.01.01 defines metal forming by plastic
deformation and distinguishes it from other forming and shaping processes like casting
and machining.
Definition of Forming
Forming is a fabrication process for solid substances by controlled
plastic deformation in order to obtain alterations of:
- the form,
- the material properties and/or
- the surface properties,
whereby the mass and material continuum remain unchanged.
K.Siegert
alu
Training in Aluminium Application Technologies
Definition of Forming 3301.01.01
TALAT 3300 3
4. 3302 Terms for Classifying Forming Processes
• Classification by State of Stress
• Classification by Type of Raw Material
• Classification by Forming Temperature
• Classification by Methods of Induction of Forces into the Work-Piece
3302.01 Classification by State of Stress (Figure 3302.01.01)
Terms for classifying the forming process:
Classification by State of Stress
Rolling, Open-Die Forming,
Pressure Forming DIN 8583 Die Forming, Indenting,
Pressing Through
Tension-Compression Drawing, Deep Drawing,
Forming DIN 8584 Collar Forming, Compressing,
Upset Bulging
Tension Forming DIN 8585 Stretch Reducing, Bulge Forming,
Stretch Forming
Bending with Linear Tool Movement,
Bend Forming DIN 8586
Bending with Rotating Tool Movement
Shear Forming DIN 8587 Shear Displacement, Twisting
alu
Classifying the Forming Process by State of Stress 3302.01.01
Training in Aluminium Application Technologies
3302.02 Classification by Type of Raw Material (Figure 3302.02.01)
Terms for classifying the forming process:
Type of Raw Material
Sheet Forming
The raw material consists of flat parts of constant thickness.
The parts produced have a three-dimensional form with
approximately constant wall thickness ( ≈ raw material thickness).
Bulk Forming
Raw parts are three-dimensional.
The parts produced are also three-dimensional but often have
very different wall thicknesses and/ or cross-sections.
alu Classifying the Forming Process by
3302.02.01
Training in Aluminium Application Technologies Types of Raw Materials
TALAT 3300 4
5. 3302.03 Classification by Forming Temperature
(Figure 3302.03.01)
Terms for classifying the forming process:
Forming Temperature
Cold Forming
Process in which the work-piece is not heated before forming,
but instead formed at room temperature.
ϑ = ϑRoom (ca. 20° C )
Warm Forming
Process in which the work-piece is heated to an elevated temperature
higher than room temperature before forming.
ϑ > ϑ Room (ca. 20° C )
alu Classifying the Forming Process by
Training in Aluminium Application Technologies Forming Temperature 3302.03.01
3302.04 Classification by Methods of Induction of Forces into the Work-Piece
(Figure 3302.04.01)
Terms for classifying the forming process:
Methods of Applying Force
Process with Indirect Force Application Process with Direct Force Application
(Deep Drawing) (Upsetting) F
FN FSt
Forming Zone
Bending Zone
Force Transmission Zone
Force Induction Zone
K. Siegert F
alu Classifying the Forming Process by
Training in Aluminium Application Technologies Methods of Applying Force 3302.04.01
TALAT 3300 5
6. 3303 Characteristic Values and Basic Laws of Metal Forming
• Flow Stress
• Plastic Strain, Rate and Acceleration
• Plastic Flow under Combined Stresses
• Law of Plastic Flow
• Flow Curves
• Average Flow Stress
• Energy Considerations
3303.01 Flow Stress
(Figure 3303.01.01)
Characteristic Values, Basic Laws
Flow Stress
F
A
The flow stress (resistance to plastic deformation) of a
material is the stress required to initiate or continue
plastic deformation under uniaxial state of stress. A0
F
Flow stress kf =
(true stress) A l0
By comparison F l
σ=
(technical stress) A0
Conversion:
ε = (l − l0 ) / l0
with
one obtains k f = σ (ε l + 1)
F
alu
Definition of Flow Stress 3303.01.01
Training in Aluminium Application Technologies
TALAT 3300 6
7. 3303.02 Plastic Strain, Rate and Acceleration
Logarithmic (True) Plastic Strain
(Figure 3303.02.01)
Logarithmic (True) Strain
The logarithmic strain ϕ (true strain; degree of deformation)
is a measure of the permanent (plastic) deformation F
dl
logarithmic (or true) strain dϕ =
dl
2
l
l1
dl l
ϕl = ∫ = ln l1 − ln l0 = ln 1 .
l0
l l0
A0
dl
As opposed to this, elongation dε = A
l0
(relative deformation)
l1
l0
l
A1
dl l − l l
l1
ε = ∫ = 1 0 = 1 − 1.
l
l0 0
l0 l0
Conversion: l1
with = (ε + 1)
l0
dl
2
F
one obtains ϕ l = ln(ε + 1)
alu
Training in Aluminium Application Technologies
Logarithmic (True) Strain 3303.02.01
Logarithmic Strain in Upsetting
(Figure 3303.02.02)
Logarithmic Strain in Upsetting
h1
ϕ h = ln
h0
Cuboid
b
ϕ b = ln 1
h0
h1
b0
l
b0
l0 l1 ϕ l = ln 1
b1 l0
r0
r1
h1
Circular ϕ h = ln
h0
h0
h1
Cylinder
r
ϕ r = ln 1 = ϕ t
r0
alu
Logarithmic Strain in Upsetting 3303.02.02
Training in Aluminium Application Technologies
TALAT 3300 7
8. Law of Volume Constancy
(Figure 3303.02.03)
Law of Volume Constancy
h0
h1
l1
l0
b0 b1
Assuming that during forming the volume of a cuboid remains constant,
the following equation is valid for a homogeneous compression:
V = h1 ⋅ b1 ⋅ l1 = h 0 ⋅ b 0 ⋅ l 0
so that: h1 b1 l 1
⋅ ⋅ = 1
h 0 b0 l 0
Taking the logarithms h b l
of both sides: ln 1 + ln 1 + ln 1 = 0
h0 b0 l0
or: ϕh +ϕh +ϕh = 0 or ∑ϕ = 0
alu
Training in Aluminium Application Technologies
Law of Volume Constancy 3303.02.03
Plastic Strain Rate
(Figure 3303.02.04)
Plastic Strain Rate
(True strain rate)
·
The true strain rate or logarithmic strain rate ϕ is the derivative of the
logarithmic strain (true strain) ϕ with time t:
dϕ
ϕ=
!
dt
From the law of volume constancy one obtains:
. . .
ϕh + ϕb + ϕl = 0
.
Σϕ = 0
·
One has to differentiate between the strain rate ϕ and the
tool speed vwz. For a homogeneous compression where
h = instantaneous height of the material being compressed,
the following relation is valid:
vwz
ϕ=
!
h
alu
Training in Aluminium Application Technologies
Plastic Strain Rate (True Strain Rate) 3303.02.04
TALAT 3300 8
9. Plastic Strain Acceleration
(Figure 3303.02.05)
Plastic Strain Acceleration
""
The plastic strain acceleration ϕ is the derivative
"
of the plastic strain rate ϕ with time t:
&
dϕ
&
&
ϕ=
dt
alu
Training in Aluminium Application Technologies
Forming Strain Acceleration 3303.02.05
3303.03 Plastic Flow under Combined Stresses
Criteria for Plastic Flow
(Figure 3303.03.01)
Criteria for Plastic Flow
Criteria for plastic flow describe the requirements
which must be fulfilled in order for plastic deformation to
occur under a multiaxial state of stress.
The requirements for flow are met when an equivalent
stress, σv , derived from the multiaxial stress state,
equals the flow stress kf:
σv = kf
In the forming technology, two types of flow hypothesis
are used to derive the comparative stress σv :
-the shear stress hypothesis according to TRESCA
-the forming energy hypothesis according to v. MISES
alu
Criteria for Plastic Flow 3303.03.01
Training in Aluminium Application Technologies
TALAT 3300 9
10. Maximum Shear Stress Hypothesis
(Figure 3303.03.02, Figure 3303.03.03, Figure 3303.03.04)
Shear Stress Hypothesis (1)
Flow occurs when the maximum shear stress τmax reaches a value
characteristic for the material, the so-called shear yield stress k:
τmax = k .
Based on the stresses ( σ1 > σ2 > σ3 ) in the MOHR stress circle,
the following equations can be derived:
τ
1 τmax
τmax = ( σ1 − σ3 ) = k
2 (=k)
σ2 σ
σ3 σ1 = σmax
1
( σmax − σmin ) = k = σmin
τmax =
2
alu
Shear Stress Hypothesis (1) 3303.03.02
Training in Aluminium Application Technologies
Shear Stress Hypothesis (2)
For a uniaxial state of tensile stress ( σ1 = σmax , σ2 = σ3 = σmin = 0 ),
the following relationship is valid:
τ
σmax - σmin = σ1 = 2k
and ( definition of flow stress ) τmax= k
σ2 = σ3 = 0 σ1 σ
σ1 = kf .
Considering the flow conditions ( σv = kf ), one
obtains:
σv = kf = σmax - σmin.
Thus, flow starts when the difference between the largest and
smallest principal normal stresses equals the flow stress.
alu
Shear Stress Hypothesis (2) 3303.03.03
Training in Aluminium Application Technologies
TALAT 3300 10
11. Shear Stress Hypothesis (3)
According to the shear stress theory, the
comparative deformation strain is equal to the
largest value of the logarithmic deformation strain:
ϕ g = ( ϕ 1 , ϕ 2 , ϕ 3 ) max .
ϕg is the principal logarithmic (or true) strain.
alu
Training in Aluminium Application Technologies
Shear Stress Hypothesis (3) 3303.03.04
Mises Flow Criterion
(Figure 3303.03.05)
Distortion Energy (von-Mises) Theory
Flow sets in when the elastic distortion energy for changing the form exceeds a criterical value.
If σ1 > σ2 > σ3, then the comparative stress is given by
1
σ v = kf = (σ 1 − σ 2 ) + (σ 2 − σ 3 ) + (σ 3 − σ 1 ) .
2 2 2
2
Using the average stress
1
σm = (σ 1 + σ 2 + σ 3 )
3
one obtains
3
σ v = kf = (σ 1 − σ m )2 + (σ 2 − σ m )2 + (σ 3 − σ m ) .
2
2
Then, according to the distortion energy theory, the comparative deformation strain becomes
ϕv =
3
(ϕ 1 + ϕ 2 2 + ϕ 32 ).
2 2
alu
Training in Aluminium Application Technologies
Distortion Energy Hypothesis (v. Mises) 3303.03.05
TALAT 3300 11
12. Yield Criteria for Plane Stress (Yield Locus)
(Figure 3303.03.06)
Yield Criteria for Plane Stress
σ3 The comparision of yield criteria for a
σ2 = 0 plane state of stresses (σ2 = 0) indicates
the stress combinations σ1 , σ3 at which
flow sets in.
kf
The curves depicting the yield criteria can
-kf thus be considered as an illustration of the
−σ1 σ1 flow theory in the σ1 , σ3 plane state of
kf
stresses.
-kf Distortion energy
theory (v. Mises)
The two flow theories sometimes deliver
somewhat different stress values for the
−σ3 start of flow. This difference is, however,
small and does not exceed 15%.
Maximum shear stress theory
(Tresca)
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Training in Aluminium Application Technologies
Yield Criteria for Plane Stress 3303.03.06
3303.04 Law of Plastic Flow
(Figure 3303.04.01)
Law of Plastic Flow
The law of plastic flow describes the correlation between stress
and the resulting deformation strain for the plastic state.
Assuming that the ratios of the deformation strains among each other
remain constant during the process, the correlation between the
deformation strain ϕ and the principal stress σ which causes the
deformation can be given by:
1
σm = (σ 1 + σ 2 + σ 3 )
3
ϕ 1 : ϕ 2 : ϕ 3 = (σ 1 − σ m ) : (σ 2 − σ m ) : (σ 3 − σ m )
Important consequences:
The logarithmic deformation strain attains the value zero
when the corresponding principal stress equals σm.
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Law of Plastic Flow 3303.04.01
Training in Aluminium Application Technologies
TALAT 3300 12
13. 3303.05 Flow Curves
General Definition of the Flow Curve
(Figure 3303.05.01)
Flow Curve
The flow stress kf of a material depends on
- the logarithmic principal deformation strain ϕg
"
- the logarithmic principal deformation strain rate ϕg
- the temperature ϑ
and, during the high speed forming, also on
""
- the principal deformation strain acceleration ϕg
" ""
i.e. kf = f(ϕg, ϕg, ϑ, (ϕg)).
The flow curve is the illustration of the flow stress kf as a
" ""
function of ϕg, ϕg, ϑ and ϕg.
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Flow Curve 3303.05.01
Training in Aluminium Application Technologies
Flow Curves at Room Temperature
(Figure 3303.05.02, Figure 3303.05.03)
Flow Curves at Room Temperature (1)
In the range of cold forming (forming temperature ϑ
is considerably lower than the recrystallisation
temperature ϑRekr ), the flow stress kf for most metallic
materials depends only on the logarithmic principal
deformation strain ϕg:
k f = f (ϕg )
kf
This dependence can be replaced for a number of
materials by the approximate relationship
k f = a ·ϕ ng
k f = a ·ϕ ng
(valid for ϕg ≠ 0, i.e. for kf ≥ Rp0.2 respectively
approximation for kf ≥ ReH)
(a and n are material constants;
ϕg
n is called strain hardening exponent)
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Flow Curves at Room Temperature (1) 3303.05.02
Training in Aluminium Application Technologies
TALAT 3300 13
14. Flow Curves at Room Temperature (2)
By taking the logarithm of the equation kf = a·ϕgn
log k f = n log ϕ g + log a
· ·
The illustration of a flow curve of the form kf = a· ϕgn
log k f in a coordinate system with axes in a logarithmic
scale is a straight line whose gradient is the
log k f = n log ϕ g + log a
· · coefficient n.
The coefficient n is a measure of the amount by which
∆ log k f
α a material hardens with increasing deformation strain
ϕg and is therefore known as the strain hardening
∆ log ϕ g coefficient.
∆ log k f Typical values of n for an aluminium-killed steel
n = tan α = are in the range of
∆ log ϕ g
0.2 ≤ n ≤ 0.25
log ϕ g
and for aluminium sheet alloys (AlMg0,4Si1,2 ka,
AlMg,5Mn w) in the range of
0.2 ≤ n ≤ 0.3
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Training in Aluminium Application Technologies
Flow Curves at Room Temperature (2) 3303.05.03
Flow Curves at Elevated Temperatures
(Figure 3303.05.04, Figure 3303.05.05 and Figure 3303.05.06)
Flow Curves at Elevated Temperature (1)
180 Material Al 99.5
N / mm² " 20°C During forming at elevated temperatures
ϕg = 4 s
-1
140 120°C (warm forming), the flow stress kf depends on
the logarithmic principal deformation strain ϕg ,
120 240°C the forming temperature ϑ and the
Flow Stress kf
100 logarithmic principal deformation strain rate
"
(deformation strain rate) ϕg:
80
60 360°C "
kf = f(ϕg , ϑ , ϕg)
40 480°C
As a rule, the flow stress kf decreases with
20
increasing temperature ϑ for a given
logarithmic principal deformation strain ϕg,
0 0.2 0.4 0.6 0.8 1.0 1.2
Logarithmic Principal
Deformation Strain ϕg
Source: Bühler a.o
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Training in Aluminium Application Technologies
Flow Curves at Elevated Temperature (1) 3303.05.04
TALAT 3300 14
15. Flow Curves at Elevated Temperature (2)
100
N / mm²
" - With increasing temperature ϑ , the influence
ϕg = 63 s
-1
of the logarithmic principal deformation strain
80 ϕg on the flow stress kf decreases.
Flow Stress kf
"
ϕg = 4 s
-1
60 "
"
- The influence of the deformation strain rate ϕg
ϕg = 0.25 s
-1
on the flow stress kf increases with increasing
40 temperature ϑ. For "a given logarithmic principal
deformation strain ϕg and a given forming
.
20 Material Al 99.5 temperature ϑ, the flow stress kf increases with
"
Temperature ϑ = 360°C increasing deformation strain rate ϕg.
0 0.2 0.4 0.6 0.8 1.0 1.2
Logarithmic Principal
Deformation Strain ϕg
Source: Bühler a.o.
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Flow Curves at Elevated Temperature (2) 3303.05.05
Training in Aluminium Application Technologies
Flow Curves at Elevated Temperature (3)
N / mm²
200
20°C 120°C For a given logarithmic principal deformation
"
strain ϕg and a given forming temperature ϑ,
100 240°C the relationship between the flow stress kf and
Flow Stress kf
80 the deformation strain rate ϕg is given
60 approximately by the equation
360°C
40 k f = b ⋅ϕ g m
!
C ϕg = 1
480°
20 Material Al 99.5 The exponent m is a measure of the hardening
0.25 40 s-1 63 of the material which depends on the
Logarithmic Principal deformation strain rate.
"
Deformation Strain Rate ϕg It increases with increasing temperature.
Source: Bühler a.o
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Training in Aluminium Application Technologies
Flow Curves at Elevated Temperature (3) 3303.05.06
TALAT 3300 15
16. 3303.06 Average Flow Stress
(Figure 3303.06.01)
Average Flow Stress
The calculation of stresses, energies and forces is
simplified, if one uses an equivalent constant flow
kf stress instead of the actual flow stress kfm. For a
forming process in the range 0 ≤ ϕg ≤ ϕg1 , it is
defined as
kf1 kf (ϕg) ϕ g1
∫k ( ϕ ) dϕ
1
kfm k fm =
kf0 ϕ g1 ϕ g1 f g
∫k ( ϕ ) dϕ
0
f g
0
As an approximation, one can use
kf 0 + kf 1
k fm =
2
0 ϕg1 ϕg kf0 - flow stress at start of process (ϕg = 0)
kf1 - flow stress at end of process (ϕg = ϕg1)
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Average Flow Stress 3303.06.01
Training in Aluminium Application Technologies
3303.07 Energy Considerations
Forming Energy
(Figure 3303.07.01)
Forming Energy
Ideal forming energy Total energy (effective forming
energy)
The ideal forming energy W id is that part of
mechanical energy which has to be used for The total forming energy Wges includes the
the forming process without external friction ideal forming energy Wid as well as the
and internal displacements. energy required to overcome the external
friction (WR) and the internal displacement
The following relation is valid for the forming (WSch), so that
energy Wid:
Wges = Wid + WR + WSch
Wid = V ∫ k f ( ϕ g ) dϕ
where V is the formed volume.
Using the average flow stress kfm, one obtains
Wid = V k fm ϕ g
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Training in Aluminium Application Technologies
Forming Energy 3303.07.01
TALAT 3300 16
17. Heat Development during Forming
(Figure 3303.07.02)
Heat Developed during Forming
Forming processes are irreversible processes. The major part of
the energy applied for the forming process is converted into heat,
causing the work-piece to warm up. Assuming that the total forming
energy Wges is converted into heat and that no heat is lost to the
environment (tool), the rise in temperature is given by the equation
Wges
∆ϑ =
V * ρ * cp
(V formed volume, ρ density and cp specific heat of the work-piece
material)
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Training in Aluminium Application Technologies
Heat Developed during Forming 3303.07.02
TALAT 3300 17
18. Literature/References
K. Lange (Editor): Umformtechnik, Springer-Verlag, Berlin, Heidelberg, New York,
Tokyo, 1984
List of Figures
Figure No. Figure Title (Overhead)
3301.01.01 Definition of Forming
3302.01.01 Classifying the Forming Process by State of Stress
3302.02.01 Classifying the Forming Process by Types of Raw Materials
3302.03.01 Classifying the Forming Process by Forming Temperature
3302.04.01 Classifying the Forming Process by Methods of Applying Force
3303.01.01 Characteristic Values, Basic Laws: Flow Stress
3303.02.01 Logarithmic (True) Strain
3303.02.02 Logarithmic Strain in Upsetting
3303.02.03 Law of Volume Constancy
3303.02.04 Plastic Strain Rate (True Strain Rate)
3303.02.05 Forming Strain Acceleration
3303.03.01 Criteria for Plastic Flow
3303.03.02 Shear Stress Hypothesis (1)
3303.03.03 Shear Stress Hypothesis (2)
3303.03.04 Shear Stress Hypothesis (3)
3303.03.05 Distortion Energy Hypothesis (v. Mises)
3303.03.06 Yield Criteria for Plane Stress
3303.04.01 Law of Plastic Flow
3303.05.01 Flow Curve
3303.05.02 Flow Curves at Room Temperature (1)
3303.05.03 Flow Curves at Room Temperature (2)
3303.05.04 Flow Curves at Elevated Temperature (1)
3303.05.05 Flow Curves at Elevated Temperature (2)
3303.05.06 Flow Curves at Elevated Temperature (3)
3303.06.01 Average Flow Stress
3303.07.01 Forming Energy
3303.07.02 Heat Developed during Forming
TALAT 3300 18