The document summarizes key aspects of scale formation during hot rolling of steel and innovations in descaling nozzle design. It discusses how scale forms due to oxidation when steel is exposed to air during hot rolling. There are two main types of scale - sticky and dry. Sticky scale can be removed with high pressure water jets up to 450 bar, while dry scale requires lower nozzle distances. New nozzle designs have eliminated issues like sharp edges and turbulence, improving impact distribution and reducing pressure drops. Computational modeling shows the new designs increase impact forces through more efficient water flow.
This document discusses the process of continuous casting of steel. It begins with an introduction and overview of the process. It then describes the three main types of continuous casting machines - vertical mould, vertical mould with bending, and curved mould. It provides details on the equipment, materials, process steps, defects, and modern developments of continuous casting. Some advantages are improved yield, quality, productivity and cost efficiency compared to ingot casting. Disadvantages include the need for a large facility and efficient cooling.
1) The document discusses various defects that can occur during steel ingot solidification such as pipe, columnar structure, blow holes, and segregation.
2) It provides remedies for preventing these defects, such as using a hot top feeder head to avoid pipe formation and soaking ingots to minimize segregation.
3) The document also covers the mechanisms of ingot solidification, describing how killed, rimmed, and semi-killed steels solidify into chill, columnar, and equiaxed zones within the ingot.
This document discusses various types of defects that can occur in hot rolled steel products, including rolled-in scale, slivers, blisters, edge cracks, folds, laminations, and more. For each defect, it provides details on appearance, possible causes related to production issues, and recommendations for process controls to remedy or prevent the defect. Specific examples with photos are also included at the end to illustrate defects observed in real hot rolled products.
Continuous casting is a steelmaking process where liquid steel is solidified into a semi-finished billet, bloom, or slab. In this process, liquid steel flows from a ladle into a water-cooled copper mold. As the steel exits the mold, it begins to solidify on the surface while the core remains liquid. The semi-solid steel strand is then cooled further through water sprays to fully solidify it into the desired cross-section. The continuous casting process allows for higher productivity and quality than traditional ingot casting.
1.This slide is about causes of breakouts during continuous casting of steel and remedies about the same
2. It will help to reduce breakouts problem during continuous casting of steel up to 80%
1) The document discusses different steelmaking processes including the Bessemer converter process, open hearth furnace process, and basic oxygen converter process.
2) The Bessemer converter process was the first major steelmaking technique but has been replaced by basic oxygen converters. It used hot metal and an oxygen blast to oxidize impurities.
3) The basic oxygen converter process is now the dominant steelmaking method. It uses a pear-shaped vessel, oxygen lancing, and produces steel in 40-60 minutes by oxidizing impurities into slag.
The document discusses continuous casting of steel and defects that can occur during the continuous casting process. It provides details on:
- Continuous casting involves delivering liquid metal into a water-cooled copper mold where the cast section is formed and then continuously withdrawn for further solidification. More than 50% of current steel production is continuously cast.
- Defects originate from factors like mold oscillation, mold flux, segregation, and phase transformations. Common defects include cracks, blowholes, inclusions, segregation, and pipes.
- Cracks are caused by mechanical and thermal stresses during casting and processing. Blowholes are caused by insufficient deoxidation or humidity. Inclusions arise from physical-chemical effects
Knife line attack occurs in a narrow band immediately adjacent to the weld metal in stabilized austenitic stainless steels such as 321 and 347. It is caused by the precipitation of chromium carbide at grain boundaries due to the dissolution of titanium carbide during welding. The high temperatures near the fusion boundary dissolve the titanium carbide, but the rapid cooling prevents it from reprecipitating, leaving free carbon that allows chromium carbide to form later and cause intergranular corrosion in a narrow strip next to the weld. Prevention methods include adding rare earth metals to reduce corrosion rates, post-weld heat treatment to dissolve chromium carbide, and using low carbon grades of stainless steel.
This document discusses the process of continuous casting of steel. It begins with an introduction and overview of the process. It then describes the three main types of continuous casting machines - vertical mould, vertical mould with bending, and curved mould. It provides details on the equipment, materials, process steps, defects, and modern developments of continuous casting. Some advantages are improved yield, quality, productivity and cost efficiency compared to ingot casting. Disadvantages include the need for a large facility and efficient cooling.
1) The document discusses various defects that can occur during steel ingot solidification such as pipe, columnar structure, blow holes, and segregation.
2) It provides remedies for preventing these defects, such as using a hot top feeder head to avoid pipe formation and soaking ingots to minimize segregation.
3) The document also covers the mechanisms of ingot solidification, describing how killed, rimmed, and semi-killed steels solidify into chill, columnar, and equiaxed zones within the ingot.
This document discusses various types of defects that can occur in hot rolled steel products, including rolled-in scale, slivers, blisters, edge cracks, folds, laminations, and more. For each defect, it provides details on appearance, possible causes related to production issues, and recommendations for process controls to remedy or prevent the defect. Specific examples with photos are also included at the end to illustrate defects observed in real hot rolled products.
Continuous casting is a steelmaking process where liquid steel is solidified into a semi-finished billet, bloom, or slab. In this process, liquid steel flows from a ladle into a water-cooled copper mold. As the steel exits the mold, it begins to solidify on the surface while the core remains liquid. The semi-solid steel strand is then cooled further through water sprays to fully solidify it into the desired cross-section. The continuous casting process allows for higher productivity and quality than traditional ingot casting.
1.This slide is about causes of breakouts during continuous casting of steel and remedies about the same
2. It will help to reduce breakouts problem during continuous casting of steel up to 80%
1) The document discusses different steelmaking processes including the Bessemer converter process, open hearth furnace process, and basic oxygen converter process.
2) The Bessemer converter process was the first major steelmaking technique but has been replaced by basic oxygen converters. It used hot metal and an oxygen blast to oxidize impurities.
3) The basic oxygen converter process is now the dominant steelmaking method. It uses a pear-shaped vessel, oxygen lancing, and produces steel in 40-60 minutes by oxidizing impurities into slag.
The document discusses continuous casting of steel and defects that can occur during the continuous casting process. It provides details on:
- Continuous casting involves delivering liquid metal into a water-cooled copper mold where the cast section is formed and then continuously withdrawn for further solidification. More than 50% of current steel production is continuously cast.
- Defects originate from factors like mold oscillation, mold flux, segregation, and phase transformations. Common defects include cracks, blowholes, inclusions, segregation, and pipes.
- Cracks are caused by mechanical and thermal stresses during casting and processing. Blowholes are caused by insufficient deoxidation or humidity. Inclusions arise from physical-chemical effects
Knife line attack occurs in a narrow band immediately adjacent to the weld metal in stabilized austenitic stainless steels such as 321 and 347. It is caused by the precipitation of chromium carbide at grain boundaries due to the dissolution of titanium carbide during welding. The high temperatures near the fusion boundary dissolve the titanium carbide, but the rapid cooling prevents it from reprecipitating, leaving free carbon that allows chromium carbide to form later and cause intergranular corrosion in a narrow strip next to the weld. Prevention methods include adding rare earth metals to reduce corrosion rates, post-weld heat treatment to dissolve chromium carbide, and using low carbon grades of stainless steel.
Continuous casting is a process that solidifies molten metal into a semi-finished billet, bloom, or slab for subsequent rolling. It involves pouring molten metal from a ladle into a tundish, then through a nozzle into a mold where it solidifies into a continuous strand. As the strand exits the mold, it passes through primary and secondary cooling zones before being bent and cut into final pieces. Continuous casting is now the dominant production method for metals like steel due to benefits like improved yield, quality, and energy efficiency compared to batch casting.
Molten steel is tapped into a ladle and alloying elements are added before being cast into molds. Steel ingots can have square, round, or polygon cross-sections depending on their intended use - squares for rolling, rectangles for flat products, and rounds for tubes. Ingot casting molds are made of cast iron and come in two types - wide end up or narrow end up. As the steel solidifies in the mold, it forms three distinct zones - a thin chill zone against the mold walls, columnar zones of elongated crystals perpendicular to the walls, and an inner equiaxed zone of larger isotropic crystals.
The document discusses different types and production processes of steel. It begins by introducing different types of steel based on carbon content, such as mild steel and alloy steels. It then describes the basic steelmaking route involving iron making, primary and secondary steelmaking, and continuous casting. The main secondary steelmaking processes discussed are AOD, VOD, CLU, ladle furnace treatment, and RH degassing. Each process's purpose and functioning are explained briefly.
This document provides an overview of alloying elements in cast iron and their effects. Key points:
1. Common alloying elements added to cast iron include copper, nickel, chromium, molybdenum, and vanadium. These improve properties like tensile strength, hardness, wear resistance, and creep resistance.
2. Optimal levels are around 1% copper, 1% nickel, 0.4% chromium, 0.5% molybdenum, and 0.2% vanadium. Alloy combinations can have synergistic effects.
3. Nodular irons are commonly alloyed with copper, nickel, molybdenum, and tin. Ferritic nodular
This presentation will provide the non-metallurgist with a basic understanding of carbon and low alloy steels. First we'll describe the carbon and low alloy steels by examining the iron-carbon binary phase diagram and understand the basic microstructures as related to carbon content. We'll discuss the nomenclature of the different carbon and alloy steel groups. We will then examine how mechanical properties are influenced through carbon content, alloy additions and heat treatment. We will also discuss the differences in carbon and low alloy steels that are specified as structural steels and high strength-low alloy (HSLA) steels. Finally, we will address the issues of material selection, processing and finishing.
1. The document discusses various heat treatment processes for steels including annealing, normalizing, and hardening.
2. Annealing involves heating and slow cooling to soften steel by refining grain structure. Types include stress relief, spheroidizing, and full annealing.
3. Normalizing refines grain size by heating above the critical temperature and slow cooling in air.
4. Hardening increases hardness and wear resistance by heating and quenching in water or oil to form martensite.
The document discusses various heat treatment processes. It defines heat treatment as operations involving heating and cooling of metals/alloys in their solid state to obtain desirable properties. It describes the stages of heat treatment as heating, soaking, and cooling. It then discusses various heat treatment processes like annealing, normalizing, hardening, and tempering in detail including their purposes, methods, and effects on material properties.
This document describes various defects that can occur in steel billets during the continuous casting process. Section I defines shape defects such as rhomboidity, bulging, concavity, and transverse depression. Section II covers internal defects like diagonal cracking, intercolumnar cracks, and central porosity/pipe. Section III outlines surface defects including bleed outs, reciprocation marks, and scoring. For each defect, the document provides details on causes and recommended actions to check things like mould alignment, secondary cooling, casting speeds, and lubrication.
This document provides an overview of metal heat treating presented by various individuals. It discusses what metal heat treating is, where it is used, why and how it is done, common heat treating processes and equipment. Specific details covered include commonly heat treated metals, types of heat treating furnaces, importance of protective atmospheres, and different heat treating processes like annealing. The document is intended to educate about key aspects of industrial metal heat treating.
This document summarizes the hot rolling and cold rolling processes used in mechanical engineering. It defines key terms like ingot, bloom, slab, and billet. It describes the main steps in hot rolling like heating, rough rolling, and finishing rolling. Advantages of hot rolling include reduced energy usage and improved material properties. Disadvantages are non-metallic inclusions and residual stresses. Cold rolling provides better dimensional control and surface finish but requires more force. Common applications of each process are also outlined.
The document discusses various aspects of hardening hypoeutectoid and hypereutectoid steels. It explains that hardening involves heating steel to the appropriate temperature, holding, and then rapidly quenching to form martensite. Factors like chemical composition, part size/shape, heating/cooling rates, and quenchant properties influence the hardening process and final properties. Different hardening methods like direct, stage, and self-tempering quenching are also summarized.
This document discusses various types of cracking that can occur in welds, including centerline cracking, heat affected zone cracking, and transverse cracking. It describes the causes and conditions required for each type of cracking, such as solidification processes, residual stresses, and hydrogen embrittlement. Prevention methods are also covered, like preheating materials, controlling hydrogen levels, and using filler metals designed to prevent cracking. The document provides detailed information on characterizing weld microstructures and properties to evaluate cracking tendencies.
The document provides information about electric arc furnaces (EAF) used for steelmaking. It discusses that EAFs use electric arcs between graphite electrodes and metallic charges to melt scrap steel at temperatures over 4000°C. EAFs allow oxidizing or reducing conditions and can use different slags. While costly due to electrical energy needs, EAFs offer flexibility in steel grades produced and can use scrap steel or hot metal from blast furnaces. Modern developments aim to reduce energy use and emissions in EAF steelmaking.
Injection metallurgy and ladle furnaces are used to refine molten steel. In injection metallurgy, desulfurizing reagents are injected into the ladle through a lance using argon gas as a carrier, which helps remove sulfur. Ladle furnaces are used to reheat, stir, and refine steel in a ladle. They allow for desulfurization, alloy additions, and inclusion removal. Both processes make use of slag and can reduce sulfur levels to 0.0002%, improving steel properties.
End splitting during long products rolling billet quality of rolling processJorge Madias
End splitting occurs because the material being rolled has not enough ductility to withstand the stress to which it is submitted. This may happens for different reasons. Coarse cracks in the billet end, like central or diagonal cracks, weakens the end, particularly when the plane where are located coincides in part with the symmetry plane between rolls. Hot ductility of steel depends on the one hand of their intrinsic features, and on the other hand, on the temperature at which they suffer the stress, and its speed.
It is important to roll the steel within the range of higher ductility at a given deformation speed. This is more critical for steels with inherent low ductility as those containing high sulfur.
The role of MnS stringers is also clear; having S controlled at the lower level of the specification is favorable. Nevertheless it is worth to mention that if caster condition is proper and excessive thermal/mechanical stresses do not arise, very high Mn/S ratio is not necessary.
Bar ends loss temperature faster. Another factor is roll cooling, it has to be correctly oriented, not excessive and keeping the position along the processing time.
In other factors experimental and modeling results are apparently controversial. There is coincidence in the fact that more friction between bar and rolls promotes splitting, but not in factors like roll diameter and reduction.
On the basis of pilot rolling results, plane, box-box, square to round and oval to round passes are favorable to avoid splitting, while oval to square promotes splitting.
This document provides an introduction and overview of a thesis investigating the use of Cold Metal Transfer (CMT) cladding to produce wear and corrosion resistant coatings. The thesis will study and optimize the operating parameters of CMT cladding for specific base and filler materials. CMT welding is considered a novel joining method that is process stable, reproducible, and cost-effective. The document outlines the goals and scope of the thesis research, which will collect experiment data from Centria University to analyze CMT cladding.
This document provides details about various topics covered in a welding course, including:
1. It outlines the topics, hours, and status of the course which covers welding science, processes, energy sources, fluxes, welding arc physics, heat flow, joint design, testing, and metallurgy.
2. It describes the key characteristics of different arc welding processes including shielded metal arc welding, gas metal arc welding, flux-cored arc welding, submerged arc welding, and gas tungsten arc welding.
3. It discusses the physics of arc welding including arc plasma formation, arc temperature, arc polarity, effects of magnetic fields, and arc types from different power sources.
This document discusses hot tear defects in castings and methods to prevent them. It provides the following key points:
- Hot tears occur during solidification due to resistance to contraction from molds/cores and uneven temperature gradients. Two conditions are needed - resistance to contraction and variable temperature gradients.
- Preventing methods include using strong molds that collapse slowly, designing castings with uniform thickness, adding chills or ribs to promote faster cooling, and controlling steel chemistry to reduce hydrogen and sulfur levels.
- Case studies using computer simulations show locations of hot zones in castings and how positioning chills or changing mold materials reduces temperatures and prevents hot tears.
Tool steels are high-quality alloy steels developed for shaping other materials. They contain carbon from 0.1-1.6% along with alloying elements like chromium, molybdenum, and vanadium. Tool steels offer better durability, strength, corrosion resistance, and temperature stability compared to other construction steels. They are used in applications involving forming, extrusion, and plastic molding. The document then discusses different types of tool steels categorized based on their intended use and hardening properties.
This document discusses the process of continuous casting of steel. It begins with an overview of steel composition and the continuous casting process, which solidifies molten metal directly into final form. Most metals are produced this way, including over 500 million tons of steel annually worldwide. The document then describes the steelmaking processes of basic oxygen furnaces and electric arc furnaces that prepare the molten steel. It focuses on the design, functions, and importance of tundishes in continuous casting, which hold molten steel and facilitate inclusion removal before casting. Key aspects of tundish design like features, insulation, nozzle placement, and refractory lining application are explained.
Replacement of lead Free Cutting Steel - 2018 research paperMukesh Karnik
this project is to study about free cutting steels and machinability property and to focus on newly developed Lead Free- Free Cutting Steel.
Points are given below about project:-
And also explained about Built up edge - Chip Formation to increase the machinability.
effect of alloying elements on free cutting steel.
manufacturing process of free cutting steel.
BASED ON CHROMIUM AND CARBON ADDITION.
To avoid Lead Hazardous problem and environmental friendly.
Continuous casting is a process that solidifies molten metal into a semi-finished billet, bloom, or slab for subsequent rolling. It involves pouring molten metal from a ladle into a tundish, then through a nozzle into a mold where it solidifies into a continuous strand. As the strand exits the mold, it passes through primary and secondary cooling zones before being bent and cut into final pieces. Continuous casting is now the dominant production method for metals like steel due to benefits like improved yield, quality, and energy efficiency compared to batch casting.
Molten steel is tapped into a ladle and alloying elements are added before being cast into molds. Steel ingots can have square, round, or polygon cross-sections depending on their intended use - squares for rolling, rectangles for flat products, and rounds for tubes. Ingot casting molds are made of cast iron and come in two types - wide end up or narrow end up. As the steel solidifies in the mold, it forms three distinct zones - a thin chill zone against the mold walls, columnar zones of elongated crystals perpendicular to the walls, and an inner equiaxed zone of larger isotropic crystals.
The document discusses different types and production processes of steel. It begins by introducing different types of steel based on carbon content, such as mild steel and alloy steels. It then describes the basic steelmaking route involving iron making, primary and secondary steelmaking, and continuous casting. The main secondary steelmaking processes discussed are AOD, VOD, CLU, ladle furnace treatment, and RH degassing. Each process's purpose and functioning are explained briefly.
This document provides an overview of alloying elements in cast iron and their effects. Key points:
1. Common alloying elements added to cast iron include copper, nickel, chromium, molybdenum, and vanadium. These improve properties like tensile strength, hardness, wear resistance, and creep resistance.
2. Optimal levels are around 1% copper, 1% nickel, 0.4% chromium, 0.5% molybdenum, and 0.2% vanadium. Alloy combinations can have synergistic effects.
3. Nodular irons are commonly alloyed with copper, nickel, molybdenum, and tin. Ferritic nodular
This presentation will provide the non-metallurgist with a basic understanding of carbon and low alloy steels. First we'll describe the carbon and low alloy steels by examining the iron-carbon binary phase diagram and understand the basic microstructures as related to carbon content. We'll discuss the nomenclature of the different carbon and alloy steel groups. We will then examine how mechanical properties are influenced through carbon content, alloy additions and heat treatment. We will also discuss the differences in carbon and low alloy steels that are specified as structural steels and high strength-low alloy (HSLA) steels. Finally, we will address the issues of material selection, processing and finishing.
1. The document discusses various heat treatment processes for steels including annealing, normalizing, and hardening.
2. Annealing involves heating and slow cooling to soften steel by refining grain structure. Types include stress relief, spheroidizing, and full annealing.
3. Normalizing refines grain size by heating above the critical temperature and slow cooling in air.
4. Hardening increases hardness and wear resistance by heating and quenching in water or oil to form martensite.
The document discusses various heat treatment processes. It defines heat treatment as operations involving heating and cooling of metals/alloys in their solid state to obtain desirable properties. It describes the stages of heat treatment as heating, soaking, and cooling. It then discusses various heat treatment processes like annealing, normalizing, hardening, and tempering in detail including their purposes, methods, and effects on material properties.
This document describes various defects that can occur in steel billets during the continuous casting process. Section I defines shape defects such as rhomboidity, bulging, concavity, and transverse depression. Section II covers internal defects like diagonal cracking, intercolumnar cracks, and central porosity/pipe. Section III outlines surface defects including bleed outs, reciprocation marks, and scoring. For each defect, the document provides details on causes and recommended actions to check things like mould alignment, secondary cooling, casting speeds, and lubrication.
This document provides an overview of metal heat treating presented by various individuals. It discusses what metal heat treating is, where it is used, why and how it is done, common heat treating processes and equipment. Specific details covered include commonly heat treated metals, types of heat treating furnaces, importance of protective atmospheres, and different heat treating processes like annealing. The document is intended to educate about key aspects of industrial metal heat treating.
This document summarizes the hot rolling and cold rolling processes used in mechanical engineering. It defines key terms like ingot, bloom, slab, and billet. It describes the main steps in hot rolling like heating, rough rolling, and finishing rolling. Advantages of hot rolling include reduced energy usage and improved material properties. Disadvantages are non-metallic inclusions and residual stresses. Cold rolling provides better dimensional control and surface finish but requires more force. Common applications of each process are also outlined.
The document discusses various aspects of hardening hypoeutectoid and hypereutectoid steels. It explains that hardening involves heating steel to the appropriate temperature, holding, and then rapidly quenching to form martensite. Factors like chemical composition, part size/shape, heating/cooling rates, and quenchant properties influence the hardening process and final properties. Different hardening methods like direct, stage, and self-tempering quenching are also summarized.
This document discusses various types of cracking that can occur in welds, including centerline cracking, heat affected zone cracking, and transverse cracking. It describes the causes and conditions required for each type of cracking, such as solidification processes, residual stresses, and hydrogen embrittlement. Prevention methods are also covered, like preheating materials, controlling hydrogen levels, and using filler metals designed to prevent cracking. The document provides detailed information on characterizing weld microstructures and properties to evaluate cracking tendencies.
The document provides information about electric arc furnaces (EAF) used for steelmaking. It discusses that EAFs use electric arcs between graphite electrodes and metallic charges to melt scrap steel at temperatures over 4000°C. EAFs allow oxidizing or reducing conditions and can use different slags. While costly due to electrical energy needs, EAFs offer flexibility in steel grades produced and can use scrap steel or hot metal from blast furnaces. Modern developments aim to reduce energy use and emissions in EAF steelmaking.
Injection metallurgy and ladle furnaces are used to refine molten steel. In injection metallurgy, desulfurizing reagents are injected into the ladle through a lance using argon gas as a carrier, which helps remove sulfur. Ladle furnaces are used to reheat, stir, and refine steel in a ladle. They allow for desulfurization, alloy additions, and inclusion removal. Both processes make use of slag and can reduce sulfur levels to 0.0002%, improving steel properties.
End splitting during long products rolling billet quality of rolling processJorge Madias
End splitting occurs because the material being rolled has not enough ductility to withstand the stress to which it is submitted. This may happens for different reasons. Coarse cracks in the billet end, like central or diagonal cracks, weakens the end, particularly when the plane where are located coincides in part with the symmetry plane between rolls. Hot ductility of steel depends on the one hand of their intrinsic features, and on the other hand, on the temperature at which they suffer the stress, and its speed.
It is important to roll the steel within the range of higher ductility at a given deformation speed. This is more critical for steels with inherent low ductility as those containing high sulfur.
The role of MnS stringers is also clear; having S controlled at the lower level of the specification is favorable. Nevertheless it is worth to mention that if caster condition is proper and excessive thermal/mechanical stresses do not arise, very high Mn/S ratio is not necessary.
Bar ends loss temperature faster. Another factor is roll cooling, it has to be correctly oriented, not excessive and keeping the position along the processing time.
In other factors experimental and modeling results are apparently controversial. There is coincidence in the fact that more friction between bar and rolls promotes splitting, but not in factors like roll diameter and reduction.
On the basis of pilot rolling results, plane, box-box, square to round and oval to round passes are favorable to avoid splitting, while oval to square promotes splitting.
This document provides an introduction and overview of a thesis investigating the use of Cold Metal Transfer (CMT) cladding to produce wear and corrosion resistant coatings. The thesis will study and optimize the operating parameters of CMT cladding for specific base and filler materials. CMT welding is considered a novel joining method that is process stable, reproducible, and cost-effective. The document outlines the goals and scope of the thesis research, which will collect experiment data from Centria University to analyze CMT cladding.
This document provides details about various topics covered in a welding course, including:
1. It outlines the topics, hours, and status of the course which covers welding science, processes, energy sources, fluxes, welding arc physics, heat flow, joint design, testing, and metallurgy.
2. It describes the key characteristics of different arc welding processes including shielded metal arc welding, gas metal arc welding, flux-cored arc welding, submerged arc welding, and gas tungsten arc welding.
3. It discusses the physics of arc welding including arc plasma formation, arc temperature, arc polarity, effects of magnetic fields, and arc types from different power sources.
This document discusses hot tear defects in castings and methods to prevent them. It provides the following key points:
- Hot tears occur during solidification due to resistance to contraction from molds/cores and uneven temperature gradients. Two conditions are needed - resistance to contraction and variable temperature gradients.
- Preventing methods include using strong molds that collapse slowly, designing castings with uniform thickness, adding chills or ribs to promote faster cooling, and controlling steel chemistry to reduce hydrogen and sulfur levels.
- Case studies using computer simulations show locations of hot zones in castings and how positioning chills or changing mold materials reduces temperatures and prevents hot tears.
Tool steels are high-quality alloy steels developed for shaping other materials. They contain carbon from 0.1-1.6% along with alloying elements like chromium, molybdenum, and vanadium. Tool steels offer better durability, strength, corrosion resistance, and temperature stability compared to other construction steels. They are used in applications involving forming, extrusion, and plastic molding. The document then discusses different types of tool steels categorized based on their intended use and hardening properties.
This document discusses the process of continuous casting of steel. It begins with an overview of steel composition and the continuous casting process, which solidifies molten metal directly into final form. Most metals are produced this way, including over 500 million tons of steel annually worldwide. The document then describes the steelmaking processes of basic oxygen furnaces and electric arc furnaces that prepare the molten steel. It focuses on the design, functions, and importance of tundishes in continuous casting, which hold molten steel and facilitate inclusion removal before casting. Key aspects of tundish design like features, insulation, nozzle placement, and refractory lining application are explained.
Replacement of lead Free Cutting Steel - 2018 research paperMukesh Karnik
this project is to study about free cutting steels and machinability property and to focus on newly developed Lead Free- Free Cutting Steel.
Points are given below about project:-
And also explained about Built up edge - Chip Formation to increase the machinability.
effect of alloying elements on free cutting steel.
manufacturing process of free cutting steel.
BASED ON CHROMIUM AND CARBON ADDITION.
To avoid Lead Hazardous problem and environmental friendly.
1. The document discusses the different forms of corrosion that can occur on metals, including general corrosion, localized corrosion (pitting and crevice), galvanic corrosion, stress corrosion cracking, and others.
2. It provides examples of each type of corrosion and recommendations for materials selection and remedies to prevent or mitigate corrosion in different applications and environments.
3. The key lessons are that carbon steel is susceptible to general corrosion while stainless steels can experience localized pitting and cracking, and that operating conditions like temperature and chemistry must be carefully controlled to prevent certain corrosion mechanisms.
Flame cutting, also known as oxy-fuel gas cutting, uses a cutting torch to direct a jet of oxygen at a metal surface preheated to ignition temperature by an oxy-acetylene flame. The oxygen reacts with the metal to form metal oxide, which is blown away by the jet, cutting through the metal. Plasma arc cutting improves on flame cutting by using a constricted electric arc and jet of ionized gas to both melt and remove the metal, allowing it to cut a wider variety of metals faster and with a narrower kerf. Both methods can cut ferrous metals but flame cutting is limited while plasma arc cutting can cut any metal.
CHARACTERISATION OF HONEYCOMB STRUCTURE.pptxLaxmiManu
Honeycomb structures are used where flat or curved surfaces with high strength-to-weight ratios are needed. They consist of arrays of hollow cells formed by thin vertical walls, which minimizes material usage. Stainless steel is often used due to its corrosion resistance. Grade 316 stainless steel provides better resistance to chlorides than Grade 304. Nickel coating is applied via electroplating to further increase corrosion and wear resistance. Testing shows that nickel-coated samples have lower corrosion rates than uncoated samples. Microstructural analysis examines properties like bonding and hardness.
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.
SURFACE TREATMENTS that change the surface chemistry of a
metal or alloy, but that do not involve intentional buildup or increase in part dimension, include:
Fabrication welding soldring and brazing1whitefeather
This document discusses different methods for joining sheet metal components, including welding and brazing. It states that welding allows multiple sheet metal parts to be joined into a single fabrication. Brazing and soldering provide permanent joints and can join metals with poor weldability or dissimilar metals. The document then describes various brazing processes like torch brazing, furnace brazing, and dip brazing, and notes that brazing requires cleaning and preparing the metal surfaces and joints.
Die Casting and its types By Raghav GuptaRaghav Gupta
This document provides an overview of different types of die casting processes and classifications of dies. It discusses the key aspects of various die casting methods including hot chamber die casting, cold chamber die casting, low pressure die casting, high pressure die casting, vacuum die casting, squeeze die casting, and gravity die casting. It also covers classifications of dies based on the number of impressions and materials poured, and provides examples of common applications for different metal alloys cast through die casting.
Review of defects in beam blank casting and the measures proposed for their e...Jorge Madias
In this paper a thorough review of the literature on defects in beam blanks is carried out. The focus is on the formation mechanism and the solutions proposed to decrease their occurrence. Surface defects included are longitudinal cracks and transverse cracks, bleeding, pinholes and slag entrapment. Internal defects are blowholes and solidification cracks (web and wing end). The review includes the techniques used to investigate the defects: metallographical characterizations, CFD, thermodynamical and thermomechanical modelling, etc. The measures taken have to do with changes in casting system (i.e. SEN design), mold design, secondary cooling modifications and regulation, strand support.
The document describes various heat treating practices for ferrous metals including annealing, hardening, normalizing, stress relieving, and tempering. It also discusses common machine tools like drilling machines, milling machines, boring machines, power saws, shapers, planers, and broaching machines. Finally, it provides information on alloying steel with chromium to improve hardenability, corrosion resistance, and strength at high temperatures.
The document discusses the history of sand casting, including early uses by the Assyrians in the 8th century BC and developments in the early 20th century with the invention of the sand slinger and sand mixer. It then provides details about the group's project to produce an exhaust manifold using sand casting, including explaining the process, materials, defects, and alternative manufacturing methods. Within the group, members will explain the different types of casting processes, the function of an exhaust manifold, suitable materials for an exhaust manifold, and details about the sand casting process.
Plain Carbon Steel is classified into:
1) Low Carbon (less than 0.25% carbon)
-Low strength, good formability
-If wear is a potential problem, can be carburized (diffusion hardening)
-Most stampings made from these steels
-AISI 1008, 1010, 1015, 1018, 1020, 1022, 1025
2). Med Carbon (0.25% to 0.6%)
-Have moderate to high strength with fairly good ductility
-Can be used in most machine elements
-AISI 1030, 1040, 1050, 1060*
3) High Carbon (0.6% to 1.4%)
-Have high strength, lower elongation
-Can be quench hardened
-Used in applications where surface subject to abrasion – tools, knives, chisels, ag implements.
-AISI 1080, 1095
The document summarizes key aspects of secondary steelmaking processes. It discusses homogenization through ladle stirring using argon bubbling or electromagnetic stirring. Degassing processes like ladle degassing and circulation degassing are also covered, which are used to remove gases from steel. Other secondary steelmaking stages discussed include heating in the ladle furnace, deoxidation using aluminum, decarburization in vacuum degassing, and desulphurization in the ladle through slag-metal reactions. Injection metallurgy techniques like powder injection and wire feeding are also summarized for adding alloying elements to molten steel.
Roll forming is a metal forming process that uses pairs of rolls to progressively bend and form sheet metal, tubes, or strips into the desired cross-sectional shape. It is commonly used to form lightweight metals like aluminum into strong, rigid parts. The roll forming process strengthens the material and improves properties like hardness and corrosion resistance. Flat rolling is the most widely used metal forming process, accounting for around 90% of forming. It involves passing slabs, strips, sheets, or plates between rolls to reduce thickness and possibly increase width. The workpiece is squeezed between the rolls, reducing thickness through compression. Friction plays an important role in drawing the workpiece into the roll gap for forming. High velocity hydroforming uses high-pressure
Roll forming is a metal forming process that uses pairs of rolls to progressively bend and form sheet metal, tubes, or strips into the desired cross-sectional shape. It is commonly used to form lightweight metals like aluminum into strong, rigid parts. The roll forming process strengthens the material and improves properties like hardness and corrosion resistance. Flat rolling is the most widely used metal forming process, accounting for around 90% of forming. It involves passing slabs, strips, sheets, or plates between rolls to reduce thickness and possibly increase width. The workpiece is squeezed between the rolls, reducing thickness through compression. Friction plays an important role in drawing the workpiece into the roll gap for forming. High velocity hydroforming uses high-pressure
Advanced Manufacturing Processes PDF Full book by badebhauEr. Bade Bhausaheb
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Scale formation and its removal in hot rolling process
1. Scale formation and its removal in Hot rolling Process
Santosh Chacko, Suresh Vasani, A.K.Ray
Lechler (India) Pvt. Ltd., Thane, India
E-mail: lechler@lechlerindia.com
During hot rolling of steel, its surface is exposed to air which leads to oxidation, resulting in
scale formation. The scale formation is affected by the temperature, steel grade, surrounding
atmosphere and the exposure time. There are two kinds of scales relevant in rolling mills – sticky
and dry scales. Sticky scales can be removed most effectively by use of high pressure water jets
upto 450 bar. Dry scales can be removed from the surface by application of descaling systems
with low distances of the descaling nozzle to the material.
Nozzle characteristics and spray header design play a major role in the performance of
descaling system. The paper focuses on the recent innovations of descaling nozzles.
INTRODUCTION
Besides the customers in the automotive industry, manufacturers of construction and agricultural
machinery using hot rolled steel for outer body parts demand defect free surfaces. The
production of oil and gas pipe lines also has set very stringent surface quality standards to the
plate mills rolling of API grades of steels. Especially existing rolling mills entering into these
lucrative markets for high quality steel often struggle to fulfill those quality requirements
because of limitations of the descaling systems installed in terms of pressure and flow rate. In
view of the above, nozzle manufacturers must have detailed knowledge of the performance of
the nozzles under operating conditions and system design. Of particular concern are:
• Nozzle spray characteristics
• Variables of impact
• Design parameters of an optimal nozzle arrangement on a descaling header
SCALE FORMATION AND SCALE TYPES DURING ROLLING
During hot rolling of strip, its surface is exposed to air which leads to its oxidation. Structure and
growth of scales so formed depends on the chemical composition of the steel material,
temperature, surrounding atmosphere, exposure time as the chemical composition of the steel
material, temperature, surrounding atmosphere, exposure time as well as surface condition before
starting the reheating. Scales are composed of Wustite (FeO), Magnetite (Fe3O4) and Hematite
(Fe2O3). Below 570O
C, FeO is not stable, only Fe3O4 and Fe2O3 are present while above this
temperature, these two oxides are accompanied by inner layer of FeO. It is generally considered
that their growth in pure iron is controlled by diffusion of iron vacancies in FeO and Fe3O4 and
by oxygen diffusion in Fe2O3.
2. In course of oxidation, certain elements contained in steel become concentrated at metal/ scale
interface. This local enrichment can be compensated by inward diffusion into metals. However,
under practical conditions, their accumulation due to oxidation is much more rapid than their
inward diffusion so that interface becomes enriched in alloy additions and residuals. For a few
alloying elements, morphology of scale can broadly described as below.
Manganese forms oxides MnO, Mn3O4 and Mn2O3 which are isomorphous to the corresponding
iron oxides with which they form solid solutions. Manganese is thus oxidized along with iron
and is present in considerable quantity in the scale.
Chromium and Aluminum have identical behaviors during oxidation. When present in large
amounts, they can form external oxides (Cr2O3, Al2O3) at metal/ scale interface which can
protect the steel from further oxidation. However, in carbon steel, their concentrations are too
low for this.
Nickel is rejected at the scale/ metal interface in form of metallic filaments which promote
pegging between the scale and the substrate. Sulphur bearing steels contain oxides (Fe, Mn)O
and sulphides (Fe, Mn)S inclusions and can form liquid oxysulphides. Minimum temperature at
which this can happen depends upon the amount of Manganese in solid solution. It is 900O
C for
10 ppm Mn and can rise to 1200O
C if steel contains 1% Mn. With formation of low melting
point phase at temperature above 960O
C, it can lead to preferential attack of metal grain
boundaries.
The effect of Silicon depends upon temperature range. Below 1177O
C, FeO reacts with silica
(SiO2) to form fayalite (Fe2SiO4) at metal/ scale interface. In contrast, a eutectic reaction occurs
between FeO and FeSiO4 at 1170O
C leading to formation of liquid phase. Liquid phase
preferentially attacks the grain boundaries of metal making the scale highly adherent.
During hot rolling, three kinds of scales are possible: primary scale, secondary scale and tertiary
scale. Primary scale is formed during reheating process of the slabs in the pusher type or walking
beam furnace. Secondary scale is formed during the rolling process in the roughing mill area and
tertiary scale within the finishing mill and coiling train.
SCALE REMOVAL FROM STRIP SURFACE BY HIGH PRESSURE WATER JET
High pressure water jet is normally used to remove the scale from hot strip surface. Primary
scale is removed by making the scale more breakable by controlling furnace atmosphere, giving
suitable reduction at vertical edger and finally using high pressure (160 -240 bar) water jet
through specially designed descaling nozzles. The secondary scale which normally forms on
3. strip surfaces while it travels from roughing stand to first finishing stands, is removed by
controlling strip temperature and applying high pressure water jets. Suitable roll cooling system
which washes scales from rolling surface is helpful in minimizing Secondary scale pickup from
work rolls to rolled strip. Mechanism of scale removal from hot surface by high pressure water
jet is quite complex. However, it is at present, believed that the following factors are responsible
for creating necessary stress for breaking / flushing the scale from steel surface.
• Steel – scale temperature difference
• Thermal gradient within scale
• Mechanical pressure by water jet
• Shear at interface
• Explosive creation of steam with cracks
Normally, the following impact pressure is required to remove the scale.
Type of scale Desired Impact Pressure, MPa
Secondary Scale 0.5
Dry Furnace Scale 1.0
Scales which adheres due to mode of furnace
operation / nickel alloy steel
5.0
DESIGN ASPECTS OF DESCALING NOZZLES
Hydraulic descaling nozzles are normally flat (jet) spray nozzles. Typical nozzle arrangement
and important nozzle parameters are shown in Fig.1.
Fig.1 Typical descaling nozzle arrangement
The exact definition of the spray characteristics such as spray angle, spray thickness and impact
distribution together with the specification of the operating parameters are the first two steps
when a spray nozzle is designed. The standardization of descaling nozzles based on the nominal
spray angle was introduced many years ago and has proved to be advantageous with regard to
header design flexibility and product availability. Four spray angles describing the width of the
4. spray are now very common. These are 22O
, 26O
, 30O
and 40O
nozzle tips each available with 13
standard flow sizes varying from 12 to 134 lpm, 16.97 to 189.5 lpm and 24 to 268 lpm at
pressure of 100, 200 and 400 bar respectively.
The area of impact is a result of the spray width and spray thickness at a given spray height. The
spray thickness (also often called spray depth) describes the width in the minor axis of the spray.
The spray thickness as well as spray width vary with the spray height.
Having selected one particular nozzle type, spray width at a given spray height is fixed by
standardized spray angle. The spray thickness, however, depends predominantly on the internal
nozzle design.
The impact distribution over the width and thickness of spray can be measured and documented
precisely as shown in Fig.2. This tool is essential for design not only of the nozzles but also for
nozzle arrangement on a header. New generation sensors (force transducers) are presently used
for better accuracy of measurement. A new measurement software has been developed for data
integration.
Fig.2 Jet Impact measurement set-up
The key components of descaling unit are
• Nozzle filter stabilizer unit
• Nozzle tip
Design features of Conventional descaling nozzle (SCALEMASTER HP)
The nozzle filter stabilizer unit of conventional descaling nozzle (SCALEMASTER HP) is
shown in Fig.3.
5. Fig.3 Nozzle filter stabilizer unit of conventional descaling nozzle (SCALEMASTER HP)
The water from the header passes through longitudinal filter slots of brass which are machined
by sawing blades leaving a sharp edge behind. It is then passed through the stabilizer which is a
star-shaped component machined from stainless steel. The stabilizer has a solid core either with
flat surface or spikes on each end. The primary function of the stabilizer is to reduce turbulence
and form a laminar water flow before it enters the nozzle tip.
The nozzle tip (Fig.4) consists of outer body containing tungsten carbide (TC) insert and in most
cases a press fit bushing which keeps the TC insert in place. A gasket in between is also required
in this case. Consequently the tip alone can consist of up to four components.
Fig.4 Nozzle tip arrangement of conventional descaling nozzle (SCALEMASTER HP)
The TC insert which shapes the spray pattern is manufactured traditionally by pressing and
machining the “Green Part” which is sintered afterwards before the final orifice is obtained by
grinding with diamond grinding wheel. Grinding is an additional process which leaves a very
sharp and sensitive orifice edge and also changes the homogeneity of the total surface structure.
In most cases, Cobalt is used as the TC binder.
The main drawbacks of the conventional descaling nozzle unit are
6. • High pressure drop in the filter stabilizer unit due to sharp edge of the braas filter slots
• Sharp and sensitive edge of nozzle tip
• Difficulty in fabricating nozzle tip
Innovations in descaling nozzle design
All the above drawbacks of the conventional nozzles have been addressed in the design of the
new generation of descaling nozzle, SCALEMASTER HPS.
In the new design, the filter stabilizer (Fig.5) which are no longer machined traditionally but
completely metal injection molded (MIM). Shapes and forms can now be produced economically
with these new production technologies which have never been possible with traditional
machining by metal cutting. As a result the entire filter stabilizer unit which is now a single piece
component entirely made from stainless steel giving it a much higher mechanical strength
against water hammers. Contact corrosion in case of low pH descaling water no longer take place
at the interface between tip and filter because brass has been completely removed from the
nozzle.
Fig.5 Filter stabilizer unit of new generation decaling nozzles (SCALEMASTER HPS)
Since the filter slots are no longer cut, their lower ends could now be internally shaped with a
smooth radius in the water flow direction eliminating most of the turbulences the sharp edges of
the old design caused at this point. With additional slots at the filter cap a more homogeneous
water flow into the filter is obtained.
The core of the stabilizer which is no longer a separate component has now been removed
providing the water a free and nearly undisturbed passage resulting in a stabilized water flow.
The nozzle tip (Fig.6) also has been completely redesigned. The body material has been changed
to pre-tempered high temperature resistant stainless steel giving a much higher strength against
7. water hammers. The slot at the tip front also has been replaced by an oval opening for the water
jet.
Fig. 6 Nozzle tip of new generation decaling nozzles (SCALEMASTER HPS)
The tungsten carbide insert is also being produced by applying metal injection molding (MIM).
After sintering no more grinding is necessary because of the highest precision which can be
guaranteed in mass production. A new internal shape and orifice geometry has been developed
for a maximum impact of the spray. The use of nickel as binder for tungsten carbide gives a
higher chemical resistance against low pH descaling water. The new orifice geometry also
reduces nozzle wear and extends the service life.
ANALYSIS OF NEW GENERATION NOZZLE VIS-À-VIS CONVENTIONALNOZZLE
Computational Fluid Dynamics (CFD) technique has been used to analyze the flow
characteristics of conventional (SCALEMASTER HP) and new generation (SCALEMASTER
HPS) nozzle.
Fig.7 shows the pressure profile inside a conventional SCALEMASTER HP nozzle. The
coloured areas are representing the water at different pressures. In the red area the water is at
maximum pressure which extends all the way though the filter slots until shortly in front of the
stabilizer. The maximum pressure loss occurs in the slots (light blue colour) of the stabilizer
because of very high water velocity. After the stabilizer in the center where the velocity is
higher, the area with the significantly reduced pressure continues until the nozzle tip orifice. It
may be noted that the pressure drop inside the nozzle is around 7 bar. This has to be
compensated by a larger tip orifice so that the specified nominal nozzle water flow can be
reached.
8. Fig. 7 Water Pressure profile inside conventional descaling nozzle (SCALEMASTER HP)
The water pressure profile inside new generation descaling nozzle (SCALEMASTER HPS) is
shown in Fig. 8. It is seen that the red zone of higher pressure extends into the center of the
nozzle tip. The overall pressure drop in this case is around 2 bar. Consequently, the tip orifice
has become smaller compared to conventional nozzle resulting in higher exit velocity of water
thereby providing higher force on the target surface. This was possible due to the optimized
internal geometries ranging from filter to TC insert, the elimination of the stabilizer core and a
new orifice tip
Fig. 8 Water Pressure profile inside new generation descaling nozzle (SCALEMASTER HPS)
The turbulence profile inside a conventional descaling nozzle (SCALEMASTER HP) is shown
in Fig.9.
The coloured areas are representing the water at different degrees of turbulences. The dark blue
areas the water is very calm like in front of the filter and in the welding nipple around the filter.
As soon as water enters the filter slot, especially where there is a sharp edge left by the sawing
blade extremely violent turbulences are being introduced (red and yellow colour). These
turbulences are being maximized further downstream by the core of the stabilizer and are
extending into the stabilizer slots where they are not being reduced. After the stabilizer directly
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s
s
11. SCALEMASTER HP (bottom) on aluminum plate. The water flow pressure was 150 bar and the
vertical height was 150 mm. As described above, the SCALEMASTER HPS concentrates the
water on a much sharper spray resulting in a reduced spray thickness a deeper and more uniform
groove.
Fig. 13 Comparison of imprint of SCALEMASTER HPS and SCALEMASTER HP
Nozzle on aluminum plate
CONCLUSION
Scales formed during hot rolling of steel mainly consists of wustite (FeO), magnetite (Fe3O4) and
hematite (Fe2O3). Wustite having high plasticity is desirable phase during rolling. The
characteristics of scale as well as their stickiness to the metal substrate depend on the type of
steels rolled and the operating conditions during rolling. With increasing demand of defect free
surface of rolled products, it is necessary to have efficient descaling system. New generation
descaling nozzle (SCALEMASTER HPS) developed by Lechler are designed to give higher and
uniform impact pressure across the spray width facilitating removal of sticky scales. It has more
operational reliability due to use of superior material and reduction in number of components and
also gives longer service life.
REFERENCES
1. Hydraulic descaling in Rolling Mills, Institute of Metals, UK, 9-10 Oct 1995
2. Steel Research International, Vol.74, No.9, 2003, pp 538-548
3. Steel Research International, Vol.75, No.6, 2005, pp 399-403
4. 37th
Mechanical Working & Steel Processing, Conf. Proceedings, ISS Vol. XXXII,1996,
p. 34
5. Schurmann S, Measurement and Mathematical Approximation of the Impact of
Descaling Nozzles, Hydraulic Descaling Conference, London, 9/2000