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What is the common surface hardening treatment in steel?

What is the common surface hardening treatment in steel? Correct Answer Carburizing

Concept:

Heat treatment is an operation involving heating and cooling of a metal or alloy so as to obtain certain desirable properties. A few important heat treatment processes are:

  1. Annealing
  2. Normalizing
  3. Hardening
  4. Tempering

Case hardening is a method used to harden the outer surface of low-carbon steel while leaving the center or core soft and ductile. Case hardening involves heating the metal to its critical temperature in some carbonaceous material. The following methods are commonly used:

  1. Carburizing
  2. Cyaniding
  3. Nitriding
  4. Induction Hardening
  5. Flame hardening

Carburizing

Carburizing is one of the most widely used surface hardening processes. 

  • The process involves diffusing carbon into low carbon steel to form a high carbon steel surface.
  • It is a heat treatment process that produces a surface that is resistant to wear while maintaining toughness and strength of the core.
  • High Carbon Steels have higher strength and hardness. Low carbon steels have higher toughness. Increasing carbon only on the surface of low carbon steel can give a hard surface and tough core.

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  • Quenching is the rapid cooling of a work-piece to obtain certain material properties. A type of heat treating, quenching prevents undesired low-temperature processes, such as phase transformations, from occurring, for instance, quenching can reduce the crystal grain size of both metallic and plastic materials, increasing their hardness. In metallurgy, quenching is most commonly used to harden steel by introducing martensite, in which case the steel must be rapidly cooled through its eutectoid point, the temperature at which austenite becomes unstable. 
  • Tempering is a heat treatment process in which the hardness of a hardened alloy is reduced by the appropriate heat-treatment process. Tempering is a heat-treatment process consisting of reheating the hardened steel to a temperature below 400°C, followed by cooling.
  • Hardness level: Nitriding > Cyaniding > Carburizing 

Related Questions

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Select the correct answer:
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