The document provides an overview of various surface heat treatment processes for metals. It discusses techniques like surface hardening, case hardening, and nitriding that involve diffusing elements like carbon or nitrogen into the surface of the metal to create a hard case while leaving the core soft. Induction hardening, carburizing, and nitriding are described as common methods for surface hardening. The document also covers other surface hardening techniques like flame hardening, vapor deposition methods, and plasma nitriding.
The document discusses heat treatment processes and tool materials. It provides an overview of different types of steels like carbon steels, alloy steels, and tool steels. It then discusses various heat treatment processes like hardening, tempering, annealing, and carburizing. Hardening involves heating steel above its critical temperature and then quenching to increase hardness. Tempering improves the toughness of hardened steel by reheating below the lower critical temperature. Carburizing introduces carbon into steel surfaces to produce a hard case. The document also covers phase diagrams and the iron-carbon diagram.
This document discusses various methods of surface hardening or case hardening steel, including:
1. Carburizing, which introduces carbon into low-carbon steel's surface, making it harder. There are pack/solid and gas carburizing methods.
2. Cyaniding uses a molten cyanide bath to absorb carbon and nitrogen into the steel surface.
3. Nitriding uses nitrogen gas to harden steel alloyed with elements like chromium.
4. Induction hardening and flame hardening quickly heat the surface with electricity or flames then quench to create a hard outer layer with a soft core.
5. Precipitation hardening involves heating, soaking,
The document discusses the weldability of various stainless steel types, including austenitic, ferritic, and martensitic stainless steels. It provides information on their typical compositions and applications. It also describes various welding techniques that can be used and issues that may occur during welding like sensitization, sigma phase formation, and hydrogen cracking. Prevention methods are outlined like using stabilizers, annealing treatments, and controlling cooling rates and heat inputs during welding.
Heat treatment is a process of heating and cooling metals and alloys to achieve desired properties. There are various heat treatment processes classified based on temperature, phase transformation or purpose. Common processes include annealing, normalizing, hardening, and tempering. Annealing relieves stresses and improves ductility while normalizing produces harder and stronger steel. Hardening involves rapid cooling from an elevated temperature to produce a hard surface. Tempering is used to reduce brittleness caused by hardening.
various types of steel basically low carbon steels and alloy steels and how the alloying elements alter the various properties of steels , a detailed study & analysis
The presentation covers various aspects of coating and deposition process in detail. The topics that are mainly covered in this PPT are
1) Type of Coating
2) Advantages and limitation for various coating process
3) Figures of various coating process
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.
Heat treatment involves controlled heating and cooling of metals to change their properties through modifying microstructure and chemistry. It is used to improve properties like hardness, toughness, ductility, and wear resistance. Common heat treatments include annealing, normalizing, hardening, and tempering. Annealing produces a soft microstructure for ductility, while normalizing produces a finer grain structure. Hardening involves quenching after heating to form martensite for hardness, followed by tempering to relieve brittleness. Alloying can increase hardenability to allow deeper hardening of parts.
The document discusses heat treatment processes and tool materials. It provides an overview of different types of steels like carbon steels, alloy steels, and tool steels. It then discusses various heat treatment processes like hardening, tempering, annealing, and carburizing. Hardening involves heating steel above its critical temperature and then quenching to increase hardness. Tempering improves the toughness of hardened steel by reheating below the lower critical temperature. Carburizing introduces carbon into steel surfaces to produce a hard case. The document also covers phase diagrams and the iron-carbon diagram.
This document discusses various methods of surface hardening or case hardening steel, including:
1. Carburizing, which introduces carbon into low-carbon steel's surface, making it harder. There are pack/solid and gas carburizing methods.
2. Cyaniding uses a molten cyanide bath to absorb carbon and nitrogen into the steel surface.
3. Nitriding uses nitrogen gas to harden steel alloyed with elements like chromium.
4. Induction hardening and flame hardening quickly heat the surface with electricity or flames then quench to create a hard outer layer with a soft core.
5. Precipitation hardening involves heating, soaking,
The document discusses the weldability of various stainless steel types, including austenitic, ferritic, and martensitic stainless steels. It provides information on their typical compositions and applications. It also describes various welding techniques that can be used and issues that may occur during welding like sensitization, sigma phase formation, and hydrogen cracking. Prevention methods are outlined like using stabilizers, annealing treatments, and controlling cooling rates and heat inputs during welding.
Heat treatment is a process of heating and cooling metals and alloys to achieve desired properties. There are various heat treatment processes classified based on temperature, phase transformation or purpose. Common processes include annealing, normalizing, hardening, and tempering. Annealing relieves stresses and improves ductility while normalizing produces harder and stronger steel. Hardening involves rapid cooling from an elevated temperature to produce a hard surface. Tempering is used to reduce brittleness caused by hardening.
various types of steel basically low carbon steels and alloy steels and how the alloying elements alter the various properties of steels , a detailed study & analysis
The presentation covers various aspects of coating and deposition process in detail. The topics that are mainly covered in this PPT are
1) Type of Coating
2) Advantages and limitation for various coating process
3) Figures of various coating process
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.
Heat treatment involves controlled heating and cooling of metals to change their properties through modifying microstructure and chemistry. It is used to improve properties like hardness, toughness, ductility, and wear resistance. Common heat treatments include annealing, normalizing, hardening, and tempering. Annealing produces a soft microstructure for ductility, while normalizing produces a finer grain structure. Hardening involves quenching after heating to form martensite for hardness, followed by tempering to relieve brittleness. Alloying can increase hardenability to allow deeper hardening of parts.
Surface heat treatment (or) case hardeningbooks5884
The document discusses various surface heat treatment and case hardening processes. It describes the purposes of these processes as producing a wear resistant hard surface, improving corrosion resistance and heat resistance, serving as an ornamental finish, and increasing the useful life of components made from low cost materials. It then lists and defines common processes like carburizing by adding carbon, nitriding by adding nitrogen, cyaniding by adding both carbon and nitrogen, carbonitriding by adding both carbon and nitrogen, and other processes like induction hardening and flame hardening. It further explains that nitriding is a process that diffuses nitrogen into the surface of a metal to create a case-hardened surface, and these processes are commonly used on low-carbon,
This document discusses various types of wear mechanisms that can occur in machines. It defines 11 main types of wear: adhesive, abrasive, erosion, polishing, contact fatigue, corrosive, electro-corrosive, fretting, electrical discharge, cavitation, and false brinelling wear. For each type of wear, it describes the wear process and provides recommendations for both mechanical and lubricant-based prevention methods. Microscopic analysis of wear debris is also discussed as a way to determine the specific type of wear that occurred.
This document provides an overview of various surface hardening techniques including case hardening methods like carburizing, nitriding, and carbonitriding which involve diffusing carbon and/or nitrogen into the surface of steel. It also discusses selective surface hardening techniques like induction hardening where only the surface is heated and quenched to produce a hard martensitic case. Common components that undergo surface hardening are gears, bearings, valves, and machine tool components to improve properties like wear and fatigue resistance. Induction hardening involves inducing current in metal to quickly heat just the surface layer to about 750-850 degrees Celsius before quenching.
The document discusses the process of deoxidizing steel. During steelmaking, oxygen dissolves into the liquid steel but not in the solid steel. Deoxidation or "killing" of steel refers to reducing the excess oxygen content before casting to prevent blowholes and inclusions. This is typically done through precipitation deoxidation using elements like aluminum, silicon, and manganese that have a higher affinity for oxygen than iron and form stable oxides. These deoxidizers are chosen based on factors like stability, deoxidizing ability, oxide melting point and density. Aluminum is the most powerful deoxidizer but its oxide alumina must be modified to remain liquid during casting.
Nitriding is a heat treatment process that diffuses nitrogen into the surface of metals like steel to create a hardened case. There are three main nitriding methods: gas, salt bath, and plasma nitriding. Nitriding increases properties like wear resistance, fatigue strength, and corrosion resistance while minimizing distortion compared to other hardening processes. Common applications of nitrided parts include use in the aircraft, automotive, and tooling industries.
The document provides an outline on heat treatment processes. It defines heat treatment and its purposes, discusses heat treatment theory and the stages of heat treatment including heating, soaking, and cooling. It describes various heat treatment processes like annealing, normalizing, hardening, and tempering. It also discusses case hardening techniques like carburizing, cyaniding, and nitriding. Finally, it introduces the TTT diagram and the microstructures obtained from different cooling rates.
The document discusses heat treatment and metal fabrication processes. It begins by defining heat treatment as a method to alter the physical and chemical properties of a material through heating and cooling. It then describes various metal fabrication techniques like forging, rolling, extrusion, and casting. The remainder of the document discusses heat treatment processes for steel like annealing, normalizing, and stress relief annealing. It explains how these processes are used to achieve desired microstructures and properties without changing the shape of the material.
This document summarizes induction hardening and flame hardening surface hardening techniques. It explains that surface hardening increases the hardness of a component's outer surface while leaving the core soft. Induction hardening uses an induction coil to heat a component's surface above the critical temperature, then quenches it to form martensite for hardness. Flame hardening uses an oxy-acetylene flame to selectively harden specific surface areas, then quenches. Both provide wear resistance and control over hardness depth. Induction hardening offers more control and less distortion while flame hardening is economical for large or complex parts.
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 discusses various heat treatments that can be used on steels, including:
- Annealing treatments like full annealing, recrystallization annealing, stress relief annealing, and spheroidization annealing.
- Normalizing to refine grain structure, harden slightly, and reduce segregation.
- Hardening by heating above the transformation temperatures and quenching to form martensite, followed by tempering.
- Factors that influence the severity of quenching and hardenability of steels, such as the quenching medium, agitation level, and alloying elements. Microstructures can vary from surface to interior based on cooling rate.
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.
Dual phase steels are microstructurally composed of 75-85% ferrite with the remainder being martensite, bainite, and retained austenite. They are processed through thermomechanical treatments to achieve better formability than ferrite-pearlite steels of similar strength. Dual phase steels work harden rapidly at low strains, have low yield strength but high ultimate tensile strength. They were initially developed in the 1960s but further improved in the 1970s for automotive applications requiring increased strength and fuel efficiency. Processing methods like continuous annealing, batch annealing, and as-rolled techniques are used to control the microstructure and resulting mechanical properties.
Mr. Mubassir I. Ghoniya has satisfactorily completed his term work in mechanical engineering at the university. The document then discusses the definition of weldability as the ease with which two metals can be joined together through welding. It outlines several factors that affect the weldability of metals, such as melting point, thermal conductivity, and surface condition. Metals with better weldability like iron and steel are easier to weld and provide mechanically sound joints.
The document discusses two surface hardening processes: cyaniding and nitriding. Cyaniding involves immersing steel in a molten bath of sodium cyanide between 870-930 Celsius to produce a hard surface. Nitriding involves heating steel in an atmosphere of ammonia between 500-650 Celsius, which dissociates to form nascent nitrogen that combines with steel elements to produce nitrides and extreme surface hardness. Both processes produce wear-resistant surfaces, but cyaniding requires careful handling due to toxicity of cyanide salts while nitriding has higher costs and longer cycle times.
Alloy-Effect of Alloying Elements in Iron and Steel.pdfAnnamalai Ram
Alloying, Effect of Alloying Iron and Steel with Carbon, Manganese, Silicon and More Elements, Impurities, Alloy Element Analysis, Spectrometers, Superalloys, Glossary
Nitriding is a surface hardening process that involves diffusing nitrogen into the surface of ferrous alloys like steel and cast iron. It is done by heating the metal between 500-590°C in contact with nitrogen gas or liquid. This creates a hard case on the surface while leaving the interior unaffected. The hardness and wear resistance of the surface is increased, improving properties like fatigue life and corrosion resistance. Common applications include engine and machine tool components. The thickness of the hardened case depends on factors like time and temperature during nitriding.
This presentation gives a brief introduction to chemical heat treatment of steels and surface hardening techniques
Keywords: Carburising, Nitriding, Carbonitriding, Flame hardening, Laser hardening, Induction hardening
Stainless steel is a corrosion-resistant steel that contains at least 10% chromium. The chromium forms a thin, protective oxide film on the steel's surface. There are several types of stainless steel classified by their chromium and other elemental contents. Producing stainless steel from an electric arc furnace alone is difficult because it requires very high temperatures to remove carbon without excessively oxidizing chromium from the melt. Solutions include increasing temperature to favor carbon removal over chromium oxidation and adding ferroalloys to recover oxidized chromium and adjust alloy content.
Heat treatment involves controlling the heating and cooling of metals to alter their microstructure and properties. The main goals of heat treatment are to refine grain structure, impart phase changes, improve properties like ductility, strength and machinability. Common heat treatment processes include annealing to relieve stresses and soften metals, hardening and quenching to increase strength, and tempering to reduce brittleness caused by hardening. The factors that influence heat treatment results are temperature, time, cooling rate, material composition and size/shape of the object.
Surface heat treatment (or) case hardeningbooks5884
The document discusses various surface heat treatment and case hardening processes. It describes the purposes of these processes as producing a wear resistant hard surface, improving corrosion resistance and heat resistance, serving as an ornamental finish, and increasing the useful life of components made from low cost materials. It then lists and defines common processes like carburizing by adding carbon, nitriding by adding nitrogen, cyaniding by adding both carbon and nitrogen, carbonitriding by adding both carbon and nitrogen, and other processes like induction hardening and flame hardening. It further explains that nitriding is a process that diffuses nitrogen into the surface of a metal to create a case-hardened surface, and these processes are commonly used on low-carbon,
This document discusses various types of wear mechanisms that can occur in machines. It defines 11 main types of wear: adhesive, abrasive, erosion, polishing, contact fatigue, corrosive, electro-corrosive, fretting, electrical discharge, cavitation, and false brinelling wear. For each type of wear, it describes the wear process and provides recommendations for both mechanical and lubricant-based prevention methods. Microscopic analysis of wear debris is also discussed as a way to determine the specific type of wear that occurred.
This document provides an overview of various surface hardening techniques including case hardening methods like carburizing, nitriding, and carbonitriding which involve diffusing carbon and/or nitrogen into the surface of steel. It also discusses selective surface hardening techniques like induction hardening where only the surface is heated and quenched to produce a hard martensitic case. Common components that undergo surface hardening are gears, bearings, valves, and machine tool components to improve properties like wear and fatigue resistance. Induction hardening involves inducing current in metal to quickly heat just the surface layer to about 750-850 degrees Celsius before quenching.
The document discusses the process of deoxidizing steel. During steelmaking, oxygen dissolves into the liquid steel but not in the solid steel. Deoxidation or "killing" of steel refers to reducing the excess oxygen content before casting to prevent blowholes and inclusions. This is typically done through precipitation deoxidation using elements like aluminum, silicon, and manganese that have a higher affinity for oxygen than iron and form stable oxides. These deoxidizers are chosen based on factors like stability, deoxidizing ability, oxide melting point and density. Aluminum is the most powerful deoxidizer but its oxide alumina must be modified to remain liquid during casting.
Nitriding is a heat treatment process that diffuses nitrogen into the surface of metals like steel to create a hardened case. There are three main nitriding methods: gas, salt bath, and plasma nitriding. Nitriding increases properties like wear resistance, fatigue strength, and corrosion resistance while minimizing distortion compared to other hardening processes. Common applications of nitrided parts include use in the aircraft, automotive, and tooling industries.
The document provides an outline on heat treatment processes. It defines heat treatment and its purposes, discusses heat treatment theory and the stages of heat treatment including heating, soaking, and cooling. It describes various heat treatment processes like annealing, normalizing, hardening, and tempering. It also discusses case hardening techniques like carburizing, cyaniding, and nitriding. Finally, it introduces the TTT diagram and the microstructures obtained from different cooling rates.
The document discusses heat treatment and metal fabrication processes. It begins by defining heat treatment as a method to alter the physical and chemical properties of a material through heating and cooling. It then describes various metal fabrication techniques like forging, rolling, extrusion, and casting. The remainder of the document discusses heat treatment processes for steel like annealing, normalizing, and stress relief annealing. It explains how these processes are used to achieve desired microstructures and properties without changing the shape of the material.
This document summarizes induction hardening and flame hardening surface hardening techniques. It explains that surface hardening increases the hardness of a component's outer surface while leaving the core soft. Induction hardening uses an induction coil to heat a component's surface above the critical temperature, then quenches it to form martensite for hardness. Flame hardening uses an oxy-acetylene flame to selectively harden specific surface areas, then quenches. Both provide wear resistance and control over hardness depth. Induction hardening offers more control and less distortion while flame hardening is economical for large or complex parts.
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 discusses various heat treatments that can be used on steels, including:
- Annealing treatments like full annealing, recrystallization annealing, stress relief annealing, and spheroidization annealing.
- Normalizing to refine grain structure, harden slightly, and reduce segregation.
- Hardening by heating above the transformation temperatures and quenching to form martensite, followed by tempering.
- Factors that influence the severity of quenching and hardenability of steels, such as the quenching medium, agitation level, and alloying elements. Microstructures can vary from surface to interior based on cooling rate.
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.
Dual phase steels are microstructurally composed of 75-85% ferrite with the remainder being martensite, bainite, and retained austenite. They are processed through thermomechanical treatments to achieve better formability than ferrite-pearlite steels of similar strength. Dual phase steels work harden rapidly at low strains, have low yield strength but high ultimate tensile strength. They were initially developed in the 1960s but further improved in the 1970s for automotive applications requiring increased strength and fuel efficiency. Processing methods like continuous annealing, batch annealing, and as-rolled techniques are used to control the microstructure and resulting mechanical properties.
Mr. Mubassir I. Ghoniya has satisfactorily completed his term work in mechanical engineering at the university. The document then discusses the definition of weldability as the ease with which two metals can be joined together through welding. It outlines several factors that affect the weldability of metals, such as melting point, thermal conductivity, and surface condition. Metals with better weldability like iron and steel are easier to weld and provide mechanically sound joints.
The document discusses two surface hardening processes: cyaniding and nitriding. Cyaniding involves immersing steel in a molten bath of sodium cyanide between 870-930 Celsius to produce a hard surface. Nitriding involves heating steel in an atmosphere of ammonia between 500-650 Celsius, which dissociates to form nascent nitrogen that combines with steel elements to produce nitrides and extreme surface hardness. Both processes produce wear-resistant surfaces, but cyaniding requires careful handling due to toxicity of cyanide salts while nitriding has higher costs and longer cycle times.
Alloy-Effect of Alloying Elements in Iron and Steel.pdfAnnamalai Ram
Alloying, Effect of Alloying Iron and Steel with Carbon, Manganese, Silicon and More Elements, Impurities, Alloy Element Analysis, Spectrometers, Superalloys, Glossary
Nitriding is a surface hardening process that involves diffusing nitrogen into the surface of ferrous alloys like steel and cast iron. It is done by heating the metal between 500-590°C in contact with nitrogen gas or liquid. This creates a hard case on the surface while leaving the interior unaffected. The hardness and wear resistance of the surface is increased, improving properties like fatigue life and corrosion resistance. Common applications include engine and machine tool components. The thickness of the hardened case depends on factors like time and temperature during nitriding.
This presentation gives a brief introduction to chemical heat treatment of steels and surface hardening techniques
Keywords: Carburising, Nitriding, Carbonitriding, Flame hardening, Laser hardening, Induction hardening
Stainless steel is a corrosion-resistant steel that contains at least 10% chromium. The chromium forms a thin, protective oxide film on the steel's surface. There are several types of stainless steel classified by their chromium and other elemental contents. Producing stainless steel from an electric arc furnace alone is difficult because it requires very high temperatures to remove carbon without excessively oxidizing chromium from the melt. Solutions include increasing temperature to favor carbon removal over chromium oxidation and adding ferroalloys to recover oxidized chromium and adjust alloy content.
Heat treatment involves controlling the heating and cooling of metals to alter their microstructure and properties. The main goals of heat treatment are to refine grain structure, impart phase changes, improve properties like ductility, strength and machinability. Common heat treatment processes include annealing to relieve stresses and soften metals, hardening and quenching to increase strength, and tempering to reduce brittleness caused by hardening. The factors that influence heat treatment results are temperature, time, cooling rate, material composition and size/shape of the object.
This document provides information on various heat treatment processes including annealing, normalizing, hardening, and tempering. It defines heat treatment as any process of heating and cooling metals to alter their properties. Annealing aims to relieve stresses and refine grains, while normalizing also improves properties. Hardening involves heating steel to form austenite and then quenching to form martensite. Tempering reduces brittleness caused by hardening. Specific methods like flame hardening and induction hardening selectively harden surfaces. Case hardening diffuses carbon or nitrogen into surfaces to create a hard case over a tough core.
This document provides information on various heat treatment processes for steel, including annealing, normalizing, hardening, and tempering. It describes the purposes and procedures for each process. Key points include:
- Annealing involves heating steel above the upper critical temperature, then slow cooling to relieve stresses and improve ductility.
- Normalizing also involves heating above the upper critical temperature, but the steel is air cooled to refine grain size while retaining some strength.
- Hardening greatly increases strength by heating steel to the austenitizing temperature then quenching in water or oil to form martensite.
- Tempering is then used to reduce brittleness by reheating hardened steel to lower temperatures.
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 heat treatment processes used to harden gears, including through hardening, case hardening, and surface hardening. Case hardening involves processes like carburizing, nitriding, and carbo-nitriding to create a hard outer case and tough inner core. Surface hardening methods include induction hardening, which selectively heats parts of the gear, and flame hardening. The document provides details on how each process is performed and the advantages they provide for improving gear hardness, wear resistance, and fatigue life.
This document discusses heat treatment processes for metals. It covers various heat treatment methods like annealing, normalizing, hardening and tempering. It describes processes like case hardening, through hardening, induction hardening and vacuum heat treatment. Key information covered includes different heat treatment methods for ferrous and non-ferrous metals, advantages of various processes, factors influencing heat treatment selection, and details of specific processes like carburizing and quenching methods.
This document describes a project to test flame hardening on low carbon steels. It discusses low carbon steels, their properties and applications. It then describes the process of flame hardening and how it was used in this project to selectively harden the surface of steel samples. Brinell hardness tests were conducted on the samples to analyze the hardness at the surface (case) versus the core after flame hardening. The results and conclusions from this analysis are presented.
Heat treatment is a series of processes involving heating and cooling metals to change their mechanical properties. It can make metals harder, stronger, and more resistant to wear or softer and more ductile. Common heat treatment processes include annealing to soften metals, normalizing to relieve stresses, hardening to increase strength, tempering to reduce brittleness caused by hardening, and surface hardening methods like carburizing and nitriding to harden just the surface.
Heat treatment processes involve heating and cooling metals to change their mechanical properties. There are several types of heat treatment processes, including softening processes like annealing which involves slowly cooling metals, hardening processes like quenching which rapidly cool metals, and tempering which heats quenched metals to reduce brittleness. Other processes include case hardening to harden surfaces, austempering to improve properties without distortion, and martempering to reduce cracking during hardening. Each process produces different microstructures and properties in metals to make them suitable for various applications.
This document discusses various heat treatment processes for steel including annealing, normalizing, hardening, and tempering. It provides details on the purposes, methods, and effects of each process. Full annealing involves heating above A3 and furnace cooling to obtain coarse pearlite and reduce hardness and increase ductility. Normalizing is done above A1 and involves air cooling, resulting in a finer pearlite structure than annealing. Hardening involves heating above A1, quenching to form martensite, and tempering to achieve the desired hardness. Retained austenite that remains after heat treatment can impact properties. Sub-zero treatment below 0°C can help eliminate retained austenite and further increase hardness.
This document discusses heat treatment processes for steels, including annealing, normalizing, hardening, tempering, and surface hardening treatments. It defines each process, explains their objectives and effects on microstructure and properties, and compares the differences between annealing and normalizing. Key points covered include how each treatment alters the steel's microstructure, hardness, strength, and other mechanical properties through controlled heating and cooling operations.
This document discusses various surface treatment methods for metals including case hardening, selective hardening, and layer additions. It provides details on specific processes like carburizing, cyaniding, nitriding, and carbonitriding for case hardening as well as flame hardening, induction hardening, and laser/electron beam hardening. Layer addition methods like physical vapor deposition, chemical vapor deposition, and thermal spraying are also outlined.
This document discusses various heat treatment processes and their effects on carbon steel properties. It describes the main heat treatment types of annealing, normalizing, hardening, carburizing, and tempering. For each it provides details on the heating temperatures, soaking times, cooling methods and their purposes such as relieving stresses, improving machinability, or inducing hardness. Hardening is described as heating steel above its critical temperature then quenching to form martensite, while tempering removes brittleness. Case hardening through carburizing and methods like pack, salt bath, and gas carburizing are also summarized.
This document discusses various heat treatment processes for altering the properties of metals including steel. It describes annealing processes for softening metals by heating and slow cooling. Hardening processes are covered, involving heating steel above critical temperatures and quenching in water to form martensite and achieve a very hard material. Tempering is introduced to reduce brittleness by reheating hardened steel. Case hardening techniques like carburizing and nitriding are outlined to create a hard outer case over a softer core.
Heat treatment 1 By
P.SENTHAMARAI KANNAN,
ASSISTANT PROFESSOR ,
DEPARTMENT OF MECHANICAL ENGINEERING,
KAMARAJ COLLEGE OF ENGINEERING AND TECHNOLOGY,
VIRUDHUNAGAR, TAMILNADU.
INDIA.
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 techniques for steels, including annealing, normalizing, hardening, and tempering. It provides an overview of the basic principles and purposes of different heat treatments, such as using annealing to produce high ductility, normalizing to refine grain structure, and hardening followed by tempering to achieve good strength and toughness. The document also describes how properties can be tailored through surface treatments versus bulk treatments, and how alloying can increase the hardenability of steels.
Literature Review Basics and Understanding Reference Management.pptxDr Ramhari Poudyal
Three-day training on academic research focuses on analytical tools at United Technical College, supported by the University Grant Commission, Nepal. 24-26 May 2024
KuberTENes Birthday Bash Guadalajara - K8sGPT first impressionsVictor Morales
K8sGPT is a tool that analyzes and diagnoses Kubernetes clusters. This presentation was used to share the requirements and dependencies to deploy K8sGPT in a local environment.
Presentation of IEEE Slovenia CIS (Computational Intelligence Society) Chapte...University of Maribor
Slides from talk presenting:
Aleš Zamuda: Presentation of IEEE Slovenia CIS (Computational Intelligence Society) Chapter and Networking.
Presentation at IcETRAN 2024 session:
"Inter-Society Networking Panel GRSS/MTT-S/CIS
Panel Session: Promoting Connection and Cooperation"
IEEE Slovenia GRSS
IEEE Serbia and Montenegro MTT-S
IEEE Slovenia CIS
11TH INTERNATIONAL CONFERENCE ON ELECTRICAL, ELECTRONIC AND COMPUTING ENGINEERING
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Advanced control scheme of doubly fed induction generator for wind turbine us...IJECEIAES
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1. Surface Heat treatment of
materials
By
P.SURESHKUMAR
ASST PROF
Dept. of Automobile Engineering
JCTCET
Coimbatore-105
2. Surface hardening is the process of hardening the surface of a
metal object while allowing the metal deeper underneath to
remain soft, thus forming a thin layer of harder metal (called the
"case") at the surface.
For example components like turbine shaft, gears, spindle,
automotive components and axle need to have a hard surface but a
soft core.
Heat treatment
Heat treatment is the process of heating and cooling metals to
change their microstructure and to bring out the physical and
mechanical characteristics that make metals more desirable.
The most common reasons metals undergo heat treatment are to
improve their strength, hardness, toughness, ductility and
corrosion resistance.
3. HEAT TREATMENT
BULK SURFACE
ANNEALING
Full Annealing
Recrystallization Annealing
Stress Relief Annealing
Spheroidization Annealing
AUSTEMPERING
THERMAL THERMO-
CHEMICAL
Flame
Induction
LASER
Electron Beam
Carburizing
Nitriding
Carbo-nitriding
NORMALIZING HARDENING
&
TEMPERING
MARTEMPERING
An overview of important heat treatments
4.
5. A1
A3
Acm
T
Wt% C
0.8 %
723C
910C
Spheroidization
Recrystallization Annealing
Stress Relief Annealing
Full Annealing
Ranges of temperature where Annealing, Normalizing and Spheroidization treatment are
carried out for hypo- and hyper-eutectoid steels.
Normalizing Heat Treatment process is heating a steel above the critical temperature,
holding for a period of time long enough for transformation to occur, and air cooling.
6.
7.
8. Through hardening of the sample
Schematic showing variation
in cooling rate from surface
to interior leading to
different microstructures
The surface of is affected by the quenching medium and experiences the best possible
cooling rate. The interior of the sample is cooled by conduction through the (hot) sample and
hence experiences a lower cooling rate. This implies that different parts of the same sample
follow different cooling curves on a CCT diagram and give rise to different microstructures.
This gives to a varying hardness from centre to circumference. Critical diameter (dc) is that
diameter, which can be through hardened (i.e. we obtain 50% Martensite and 50% pearlite at
the centre of the sample).
10. Severity of quench values of some typical quenching conditions
Process Variable H
Air No agitation 0.02
Oil quench No agitation 0.2
" Slight agitation 0.35
" Good agitation 0.5
" Vigorous agitation 0.7
Water quench No agitation 1.0
" Vigorous agitation 1.5
Brine quench
(saturated Salt water)
No agitation 2.0
" Vigorous agitation 5.0
Ideal quench
Note that apart from the nature of the
quenching medium, the vigorousness of the
shake determines the severity of the quench.
When a hot solid is put into a liquid
medium, gas bubbles form on the surface of
the solid (interface with medium). As gas
has a poor conductivity the quenching rate is
reduced. Providing agitation (shaking the
solid in the liquid) helps in bringing the
liquid medium in direct contact with the
solid; thus improving the heat transfer (and
the cooling rate). The H value/index
compares the relative ability of various
media (gases and liquids) to cool a hot solid.
Ideal quench is a conceptual idea with a heat
transfer factor of ( H = ).
1
[ ]
f
H m
K
Severity of Quench as indicated by the heat transfer equivalent H
f → heat transfer factor
K → Thermal conductivity
Before we proceed further we note that we have a variety of quenching media at our
disposal, with varying degrees of cooling effect. The severity of quench is indicated by the
‘H’ factor (defined below), with an ideal quench having a H-value of .
Increasing
severity
of
quench
11. Surface hardening: why & how?
Components like gear, shaft or spindle need a hard / wear resistant surface but a soft / tough
core.
Section size of such components is often too large to be uniformly hardened even on severe
quenching.
More over the time lag between the transformations at the surface and the core results in an
unfavorable tensile residual stress at the surface.
Recall the general thumb rule that the region that transforms later is likely to have compressive
residual stress.
The surface is likely to transform first in steel having the same composition all through its
section.
Therefore surface would have residual tensile stress. Depending on its magnitude it may lead to
cracking or distortion.
The presence of residual tensile stress is also harmful as it would reduce fatigue life of critical
components like turbine shaft or landing gear of an aircraft.
The purpose of surface hardening is to develop a hard surface with compressive residual stress,
to improve its wear resistance, to increase its fatigue life and to avoid susceptibility to
distortion and cracking.
12. There are several other ways the strength or the hardness of the
surface can be increased without adversely affecting the toughness
of the core.
Some of the most common techniques are as follows:
1. Induction hardening
2. Case carburizing + case hardening
3. Nitriding
4. Shot peening
5. Hard facing, coating or surface alloying
Formation of Martensite is primarily responsible for the
development of very high strength in steel.
However you need to cool a component made of steel very fast to
get martensite
13.
14.
15. Layer additions Substrate treatment
Hard-facing
Fusion hard-facing
Thermal spray
Coatings
Electrochemical plating
Chemical vapor deposition (electroless plating)
Thin films (physical vapor deposition, Sputtering,
ion plating)
Ion mixing
Diffusion methods
Carburizing
Nitriding
Carbonitriding
Nitrocarburizing
Boriding
Titanium-carbon diffusion
Toyota diffusion process
Selective hardening methods
Flame hardening
Induction hardening
Laser hardening
Electron beam hardening
Ion implantation
Selective carburizing and nitriding
Engineering methods for surface hardening
16. Induction hardening
• Induced eddy currents
heat the surface of the
steel very quickly and is
quickly followed by jets of
water to quench the
component.
• A hard outer layer is
created with a soft core.
The slideways on a lathe
are induction hardened.
17.
18.
19.
20. Induction hardening is very effective for surface hardening of plain carbon steel
having 0.35‐0.70%C.
The salient features of induction hardening are as follows:
• Heat the surface to a temperature above A3 (austenitic region)
• Core does not get heated : the structure remains unaltered
• Surface converts to martensite on quenching.
• Fast heating & short hold time: needs higher austenization temperature
• Martensite forms in fine inhomogeneous grains of austenite
• Applicable to carbon steels (0.35 – 0.7C)
• Little distortion & good surface finish
21. Once the process is complete the microstructure of the surface gets transformed into
martensite while that at its core remains unaltered.
22.
23. Carburizing
Carburizing, also referred to as Case Hardening, is a heat treatment process that produces a
surface which is resistant to wear while maintaining toughness and strength of the core.
This treatment is applied to low carbon steel parts after machining as well as high alloy
steel bearings, gears and other components.
Carburizing increases strength and wear resistance by diffusing carbon into the surface of
the steel creating a case while retaining a substantially lesser hardness in the core. This
treatment is applied to low carbon steels after machining.
Most carburizing is done by heating components in either a pit furnace, or sealed
atmosphere furnace and introducing carburizing gases at temperature.
Gas carburizing allows for accurate control of both the process temperature and carburizing
atmosphere (carbon potential).
Carburizing is a time/temperature process; the carburizing atmosphere is introduced into
the furnace for the required time to ensure the correct depth of case.
The carbon potential of the gas can be lowered to permit diffusion, avoiding excess carbon
in the surface layer.
24. Carburizing cannot be done in ferrite phase as it has very low solid solubility for carbon at
room temperature. It is done in the Austenite region above 727°C in carbon rich
atmosphere.
Types of carburizing
i. Pack carburizing
ii. Gas carburizing
iii. Liquid carburizing
For iron or steel with low carbon content, which has poor to no hardenability of its own,
the case hardening process involves infusing additional carbon into the case.
Case hardening is usually done after the part has been formed into its final shape, but can
also be done to increase the hardening element content of bars to be used.
Because hardened metal is usually more brittle than softer metal, through-hardening (that
is, hardening the metal uniformly throughout the piece) is not always a suitable choice for
applications where the metal part is subject to certain kinds of stress.
In such applications, case hardening can provide a part that will not fracture (because of
the soft core that can absorb stresses without cracking) but also provides adequate wear
resistance on the surface.
25. Pack carburizing
• The component is packed
surrounded by a carbon-rich
compound and placed in the
furnace at 900 degrees.
• Over a period of time carbon
will diffuse into the surface of
the metal.
• The longer left in the furnace,
the greater the depth of hard
carbon skin. Grain refining is
necessary in order to prevent
cracking.
A major limitation of pack carburizing is poor control over temperature & carburization
depth.
On completion of the process the steel parts are cooled slowly. Direct quenching is not
possible as the job is surrounded by carburizing mixture packed in a sealed box having high
thermal mass.
This can be overcome by using gaseous or liquid carburizing medium.
26. • Salt bath carburizing. A molten salt bath (sodium cyanide, sodium carbonate and sodium chloride) has the
object immersed at 900 degrees for an hour giving a thin carbon case when quenched.
• Gas carburizing. The object is placed in a sealed furnace with carbon monoxide allowing for fine control of the
process.
• Gas carburization is done by keeping the samples at the carburizing temperature for a specified time in a
furnace having a mixture of carburizing and neutral gas. CH4 and CO are the most commonly used
carburizing gas.
• It is usually mixed with de‐carburizing (H2 and CO2) and neutral gases (N2).
• This helps maintain a close control over carbon potential. It should be enough to maintain %C at in the range
1.0‐1.2% at the surface.
• In the presence of Fe the carburizing gases decompose to produce nascent carbon that diffuses into steel.
CH4 = C (Fe) + 2H2
2CO = C (Fe) + CO2
• It provides excellent control over the furnace temperature and atmosphere (carbon potential).
• Samples after carburization can be directly quenched.
27. Liquid carburization
It is done by keeping the job in a salt bath consisting of 8% NaCN + 82 BaCl2 + 10 NaCl.
It allows precise temperature control and rapid heat transfer. Carburization takes place due
to the formation of nascent carbon.
The chemical reactions that occur in the presence of Fe are as follows:
BaCl2 + NaCN = Ba(CN)2 +NaCl
Ba(CN)2 = C (Fe) + BaCN2
What is the chemical CN?
A cyanide is a chemical compound that contains the group C≡N. This group, known as the
cyano group, consists of a carbon atom triple-bonded to a nitrogen atom.
The sample can be quenched immediately after carburization.
Nitriding
Nitrides are formed on a metal surface in a furnace with ammonia gas circulating at 500
degrees over a long period of time (100 hours). It is used for finished components.
If steel is heated in an environment of cracked ammonia it picks up nitrogen.
Nitrogen like carbon forms interstitial solid solution with iron. If it is present in excess it forms
nitride (Fe4N). It is extremely hard and brittle.
28. Nascent nitrogen that forms at the surface of steel as ammonia comes in contact
with Fe.
This diffuses into iron lattice and form nitride as and when the amount of
nitrogen in steel exceeds its solubility limit.
The presence of alloying elements having high affinity for nitrogen increases
nitrogen pick up.
The formation of nitride within the matrix results in a substantial increase in the
hardness of steel.
The preferred thickness of the hardened layer is around 20 micro meter.
The hardness of the nitride layer is usually in the range of 1000‐2000Hv.
Nitriding of steel is carried out only after it has been hardened and tempered. It
is the last heat treatment given to steel.
29. Flame hardening
• Gas flames raise the
temperature of the outer
surface above the upper
critical temp. The core
will heat by conduction.
• Water jets quench the
component.
38. Physical Vapor Deposition – Thermal
PVD
• Thermal PVD – also called Vacuum Deposition
– Coating material (typically metal) is evaporated by melting
in a vacuum
– Substrate is usually heated for better bonding
– Deposition rate is increased though the use of a DC current
(substrate is the anode so it attracts the coating material)
– Thin ~0.5 mm to as thick as 1 mm.
39. Physical Vapor Deposition – Sputter Deposition
• Vacuum chamber is usually backfilled with Ar gas
• Chamber has high DC voltage (2,000-6,000 V)
• The Ar becomes a plasma and is used to target the
deposition material. The impact dislodges atoms from the
surface (sputtering), which are then deposited on the
substrate anode
• If the chamber is full of oxygen instead of Ar, then the
sputtered atoms will oxidize immediately and an oxide will
deposit (called reactive sputtering)
40. Physical Vapor Deposition – Ion Plating
• Combination of thermal PVD and sputtering
• Higher rate of evaporation and deposition
• TiN coating is made this way (Ar-N2
atmosphere)
– The gold looking coating on many cutting tools to
decrease the friction, increase the hardness and
wear resistance
41. Chemical Vapor Deposition
• Deposition of a compound (or element) produced by a
vapor-phase reduction between a reactive element and gas
– Produces by-products that must be removed from the process as
well
• Process typically done at elevated temps (~900ºC)
– Coating will crack upon cooling if large difference in thermal
coefficients of expansion
– Plasma CVD done at 300-700ºC (reaction is activated by plasma)
• Typical for tool coatings
• Applications
– Diamond Coating, Carburizing, Nitriding, Chromizing, Aluminizing
and Siliconizing processes
– Semiconductor manufacturing
42.
43. Plasma Nitriding
Plasma nitriding, also known as ion nitriding or glow discharge nitriding, is a gas nitriding
process enhanced by a plasma discharge on the part to be nitrided.
The plasma is gas that when exposed to an electrical potential is ionized and glows. The
parts to be nitrided are connected as a cathode and the furnace walls are the anode.
They are supplied with a potential between 0.3 and 1KV. Particles are accelerated and hit
the cathode (work piece) transferring all their kinetic energy and heating it.
For gas particles to have enough kinetic energy to transfer, they need to have a
considerable large mean free path and in this way gain speed for collision with the
substrate before colliding with another gas particle.
This is why this process and mostly all plasma processes work under vacuum as a measure
to increase the mean free path of the accelerated particles.
The pressure used for plasma nitriding is normally between 100 – 1000Pa. Other authors
suggest a narrower range between 50 – 500Pa.
This pressure is considered as a rough vacuum since there are other processes that use
much higher vacuum values.
44. The chemical reaction when ammonia dissociated was explained in the preceding section.
In the case of plasma nitriding, the process gases are introduced separately.
One combination that is often used is Nitrogen + Hydrogen. Argon is also used in the initial
stages as a plasma sputtering gas for surface cleaning of the substrate to be nitrided.
The voltage drop occurs in what is called the plasma sheath which is a positive charged
area where ions are accelerated towards the cathode and have their highest kinetic
energies.
45. During ion nitriding three reactions will occur at the surface of the material being treated.
In the first reaction, iron and other contaminants are removed from the surface of the
work by an action known as sputtering or by a reducing reaction with hydrogen.
The impact of hydrogen or argon ions bombarding the work surface dislodges the
contaminant that will be extracted by the vacuum system. The removal of these
contaminants allows the diffusion of nitrogen into the surface
During the second reaction, and as a result of the impact of the sputtered ion atoms, case
formation begins at the work surface of iron nitrides.
Sputtered Fe + N = FeN
During the third reaction, a breakdown of the FeN begins under the continuous sputtering
from the plasma.
This one causes the instability of the FeN which begins to break down into the e phase
followed by the g’ phase and a iron-nitrogen compound zone
46. Surface Treatment
Type
Concepts and Applications of the process
Electroplating
A method of forming metallic coatings (plating films) on subject metal surfaces submerged in solutions containing ions by
utilizing electrical reduction effects. Electoplating is employed in a wide variety of fields from micro components to large
products in information equipment, automobiles, and home appliances for ornamental plating, anti-corrosive plating, and
functional plating.
Electroless Plating
A plating method that does not use electricity. The reduction agent that replaces the electricity is contained in the plating
solution. With proper re-processing, virtually any material such as paper, fabrics, plastic and metals can be plated, and the
distribution of the film thickness is more uniform, but slower than electroplating. This is different from chemical plating by
substitution reaction.
Chemical Process
(Chemical Coating)
The process creates thin films of sulfide and oxide films by chemical reactions such as post zinc plating chromate treatment,
phosphate film coating (Parkerizing), black oxide treatments on iron and steels, and chromic acid coating on aluminum. It is
used for metal coloring, corrosion protection, and priming of surfaces to be painted to improve paint adhesion.
Anodic Oxidation
Process
This is a surface treatment for light metals such as aluminum and titanium, and oxide films are formed by electrolysis of the
products made into anodes in electrolytic solutions. Because the coating (anodizing film) is porous, dyeing and coloring are
applied to be used as construction materials such as sashes, and vessels. There is low temperature treated hard coating
also.
Hot Dipping
Products are dipped in dissolved tin, lead, zinc, aluminum, and solder to form surface metallic films. It is also called
Dobuzuke plating and Tempura plating. Familiar example is zinc plating on steel towers.
Vacuum Plating
Gasified or ionized metals, oxides, and nitrides in vacuum chambers are vapor deposited with this method. Methods are
vacuum vapor deposition, sputtering, ion plating, ion nitriding, and ion implantation. Titanium nitride is of gold color.
Painting
There are spray painting, electrostatic painting, electrodeposition painting, powder painting methods, and are generally
used for surface decorations, anti-rusting and anti-corrosion. Recently, functional painting such as electro-conductive
painting, non-adhesive painting, and lubricating painting are in active uses.
Thermal Spraying
Metals and ceramics (oxides, carbides, nitrides) powders are jetted into flames, arcs, plasma streams to be dissolved and
be sprayed onto surfaces. Typically used as paint primer bases on larger structural objects, and ceramic thermal spraying
for wear prevention.
Surface Hardening
This is a process of metal surface alteration, such as carburizing, nitriding, and induction hardening of steel. The processes
improve anti-wear properties and fatigue strength by altering metal surface properties.
Metallic Cementation
This is a method of forming surface alloy layers by covering the surfaces of heated metals and metal diffusion at the same
time. There is a method of heating the pre-plated products, as well as heating the products in powdered form of metal to
be coated.
There are following types of surface treatments.
47. What is meant by Austempering?
Austempering is heat treatment that is applied to ferrous metals, most notably steel and
ductile iron. In steel it produces a bainite microstructure whereas in cast irons it produces
a structure of acicular ferrite and high carbon, stabilized austenite known as ausferrite.
What is Martempering process?
Martempering is a heat treatment for steel involving austenitisation followed by step
quenching, at a rate fast enough to avoid the formation of ferrite, pearlite or bainite to a
temperature slightly above the martensite start (Ms) point.