_______ is a process of case hardening in which the outer layer is made hard by increasing amount of carbon.
Carburizing
Concept:
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:
- Carburizing
- Cyaniding
- Nitriding
- Induction Hardening
- Flame hardening
Carburizing
- Carburizing is one of the most widely used surface-hardening processes.
- The process involves diffusing carbon into low-carbon steelto form a high-carbon steel surface.
- The Carburizing process is also referred to as case hardening or case carburizing process.
- It is a heat treatment process that produces a surface that is resistant to wear while maintaining the 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.
Tempering
- Tempering is the process of annealing martensite at low temperatures.
- Tempering is a heat-treatment process consisting of reheating the hardened steel to a temperature below 400°C, followed by cooling.
- Steel in its hardened condition is generally too brittle to be used for certain functions. Therefore, it is tempered. The aims of tempering are:
- to relieve the internal stresses
- to regulate the hardness and toughness
- to decrease the brittleness
- to restore some ductility
- to induce shock resistance
Annealing
- Annealing is a heat treatment process in which the material is taken to a high temp, kept there for some time, and then cooled in the furnace itself.
- Cooling is done slowly to avoid distortion.
- The benefits of annealing are:
- Relieve stresses
- Increase softness, ductility, and toughness
- Produce a specific microstructure
- Improve machining characteristic
Normalizing
- Heat the steel from 30°C to 50°C above its upper critical temp, held for about fifteen minutes, and then allowed it to cool down in still air.
- The homogeneous structure provides a higher yield point, ultimate tensile strength, and impact strength with lower ductility to steel.
- The main purpose of normalizing is
- Refine grain size in metal , improve strength and hardness, reduce ductility
- Remove cold work stress.
- Remove dislocations due to hot working.
Similar Questions
With which one of the following heat treatment processes do we obtain a scale-free surface on the component?
Cyaniding and nitriding are two methods of
Which of the following is NOT a heat treatment process?
____ is a cooling medium applied for normalizing process.
Which gas is used for nitriding process?
Case hardening is done on mild steel by _____ process.
For what purpose annealing is done.
While preparing a hardened plain carbon steel die, a machinist must ensure uniform grain structure and relieve internal stresses before hardening. Which sequence of heat treatments should be followed to achieve this?
Which of the following best describes the main difference between annealing and normalizing in heat treatment?
What is the main purpose of heat treatment in metals?
Important Questions from Heat Treatment
With which one of the following heat treatment processes do we obtain a scale-free surface on the component?
Cyaniding and nitriding are two methods of
The heat treatment of steel to obtain softness, improved machinability, increased ductility, to relieve internal stresses, and to refine the grain size is called
After hardening process, the metal becomes more ________
Which of the following is NOT a heat treatment process?
