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Heat treatment
Heat treatment
Heat treatment
Heat treatment
Heat treatment
Heat treatment
Heat treatment
Heat treatment
Heat treatment
Heat treatment
Heat treatment
Heat treatment
Heat treatment
Heat treatment
Heat treatment
Heat treatment
Heat treatment
Heat treatment
Heat treatment
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Heat treatment

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just keep some basic in mind, its give u enough information about this topic.

just keep some basic in mind, its give u enough information about this topic.

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  • 1. HEAT TREATMENT Dr. H. K. Khaira Professor in MSME MANIT, Bhopal
  • 2. Introduction • Lifting devices in their various forms are constructed from a range of materials that have specific properties for the function they will perform. • The inherent structure that provides these necessary properties may not be capable of meeting a range of “working demands”. • It is then necessary to enhance these properties by some means.
  • 3. Introduction • Alloying, cold working processes and heat treatment are ways of altering the structure of a material to improve its properties. • These structure-altering procedures are often employed in combination to achieve the desired results. • For example, iron alloyed with carbon produces steel that is further enhanced with other metals such as molybdenum, chromium and vanadium. • The forging process will again change the properties, as will heat treatment.
  • 4. Tools for Controlling Properties of Metals • 1. Alloying • 2. Cold Working • 3. Heat treatment
  • 5. Heat Treatment • Heat treatment is defined as heating a metal to a specified temperature, keeping it at that temperature for some time followed by cooling at a specified rate. • It is a tool to get required microstructure and properties in the metal.
  • 6. Heat treatment Heat treatment - controlled heating and cooling basically The basic steps of heat treatment are: Heating → Soaking → Cooling Handouts 2 6
  • 7. Important Parameters in Heat treatment Heating -> Temperature Soaking -> Cooling Time of soaking Rate of cooling Medium of cooling -Different combinations of the above parameters Give rise to different heat treatments Handouts 2 7
  • 8. Cooling Rates
  • 9. Types of Heat Treatments • • • • • 1. Annealing 2. Normalizing 3. Hardening 4. Tempering 5. Precipitation Hardening
  • 10. Annealing • Annealing is a heat treatment in which the metal is heated to a temperature above its recrystallisation temperature, kept at that temperature some time for homogenization of temperature followed by very slow cooling to develop equilibrium structure in the metal or alloy. • The steel is heated 30 to 50oC above Ae3 temperature in case of hypo-eutectoid steels and 30 to 50oC above A1 temperature in case of hyper-eutectoid temperature • The cooling is done in the furnace itself. • The aim of annealing is to increase the ductility.
  • 11. Normalizing • Normalizing consists of heating a suitable steel to a temperature 50-1000 C above Ae3 temperature in case of hypoeutectoid steels and above Acm temperature in case of hypereutectoid steel, soaking for sufficient time and then cooling in still air. • The aim of normalizing is to increase the toughness.
  • 12. Hardening • In hardening heat treatment, the steel is heated 30 to 50oC above Ae3 temperature in case of hypo-eutectoid steels and 30 to 50oC above A1 temperature in case of hyper-eutectoid temperature, held at that temperature for some time followed by cooling at a rate faster than the critical cooling rate to produce martensite which is a hard phase. • The aim of hardening is to increase the hardness and strength of the steel.
  • 13. Critical Cooling Rate Critical cooling rate
  • 14. Tempering • Tempering consists of heating a hardened steel to a temperature below eutectoid temperature and keeping it at that temperature for a specified time to reduce brittleness followed by air cooling. • The aim of tempering is to decrease brittleness of hardened steel.
  • 15. Precipitation Hardening • Precipitation Hardening (or Age Hardening) is a heat treatment in which the strength increases due to precipitation of second phase particles in the parent phase. • The aim of precipitation hardening is to increase the hardness and strength .
  • 16. Heat Treatment Temperature ←Acm The temperature ranges to which the steel has to be heated for different heat treatments A3 →
  • 17. Cooling Rates for Different heat treatments
  • 18. Tempering

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