Common Types of Heat Treatment and Their Purpose
In order to make metal workpieces have the required mechanical properties, physical properties and chemical properties, besides reasonable selection of materials and various forming processes, heat treatment processes are often essential. Heat treatment generally does not change the shape and overall chemical composition of the workpiece, but imparts or improves the performance of the workpiece by changing the microstructure inside the workpiece or changing the chemical composition on the surface of the workpiece. Its characteristic is to improve the internal quality of the workpiece, and its function is to improve the mechanical properties of the material, eliminate residual stress and improve the machinability of the metal.
Published: Dec 13, 2022
Heat treatment is to heat the metal material to a certain temperature, keep it warm for a certain period of time, and then cool it down to room temperature or lower at a certain rate, so as to improve the structure of the material and obtain a material with excellent performance. It generally refers to the treatment of metal materials, especially steel. Commonly used classification methods include normalizing, annealing, quenching, tempering and surface hardening.
The following introduces the types and purposes of eight common heat treatments:
- Normalizing
Type:
- Ordinary normalization
- Two-stage normalization
- Secondary normalization
- Isothermal Normalization
Purpose:
- Eliminate the bad structure produced by processing, and normalize the steel, so as to facilitate the subsequent manufacturing process.
- Make coarser grains finer and improve mechanical properties.
- Annealing
Type:
- Diffusion annealing
- Fully annealed
- Isothermal annealing
- Low temperature annealing
- Relaxation annealing
- Spheroidizing annealing
Purpose:
- Diffusion and homogenization of alloy components.
- Adjust the organization.
- Soften to improve normal temperature workability and machinability.
- Stress relief.
- Carbide spheroidization to improve workability and mechanical properties.
- Eliminate hydrogen embrittlement.
- Quenching
Type:
- Ordinary quenching
- Time quenching (interrupted quenching)
- Hemp Tempering (US)
- Voss Temper
Purpose:
- Hardened, ie strengthened steel.
- Subzero Treatment
Disadvantages of residual washer field iron:
- Poor quenching hardness (insufficient, uneven)
- Poor wear resistance
- Quenching deformation is large
- Dimensional stability becomes poor during use, or even damaged
Purpose:
- After quenching, the residual washer field iron is treated below 0 ℃ to transform it into moss field iron.
- Tempering
Type:
- Low temperature tempering
- High temperature tempering
Purpose:
- Eliminate the stress of quenched Ma Tian loose iron
- Organizational stabilization
- Adjust mechanical properties (i.e. toughness)
- Induction Hardening
Type:
- High frequency induction hardening
- Medium frequency induction hardening
- Low frequency induction hardening
Purpose:
- Utilize the induction heating effect of high-frequency current, and then apply quenching hardening. Harden the surface of the steel and generate surface compressive stress, improving the fatigue resistance of the workpiece.
- Carburizing
Type:
- Solid carburizing
- Liquid carburizing
- Gas carburizing
Purpose:
- Improve surface hardness and wear resistance
- Improve the fatigue resistance of the workpiece
- Nitriding
Type:
- Solid nitriding
- Liquid nitriding
- Gas nitriding
- Ion Nitriding
Purpose:
- Improve surface hardness and wear resistance
- Improve the corrosion resistance of the surface
- Improve the heat resistance of the surface
- Improve the fatigue resistance of the workpiece
Published by Dec 13, 2022
Source :SH SHUANG HO METAL
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