Why do metals need to be heat treated?

Metal heat treatment is a technique of changing the inner structure of a metal or alloy by heating, holding and cooling in some medium to obtain the desired properties.

Features:

1. Increase process performance.

For example, annealing treatment is often required before processing to adjust hardness and increase cold workability; normalizing and spheroidizing annealing are often required to increase the machinability of high-carbon steel tools; some ingots with severe composition segregation also need to be uniform before heat treatment. chemical annealing.

2. Increase the performance of the material or workpiece.

If the gear adopts the correct heat treatment process, its service life can be several times or dozens of times longer than that of the unheated gear; some alloying elements are infiltrated into the low-carbon steel, and the performance of "external strength and internal toughness" can be obtained; malleable cast iron can be used for a long time after a long time. Annealing treatment, the plasticity of white cast iron is greatly increased.

The heat treatment process generally includes three processes of heating, heat preservation and cooling, and sometimes only two processes of heating and cooling.

Metal heat treatment can be divided into three categories: bulk heat treatment, surface heat treatment and chemical heat treatment.

Depending on the heating medium, it can be divided into several heating methods and heating methods.

Overall heat treatment:

The overall heat treatment is a heat treatment method that heats the entire workpiece, cools it at an appropriate rate after a long time, and changes the mechanical properties of the workpiece by changing the microstructure. For steel materials, the entire heat treatment can be divided into four basic processes: annealing, normalizing, quenching and tempering.

Surface heat treatment:

The method of heat treating its surface is just heat treating its surface. The main methods of surface heat treatment are flame heating surface quenching and induction heating surface quenching. Commonly used heat sources are oxyacetylene or oxypropane flame, induced current, laser and electron beam.

(Surface quenching: Use high-frequency induction current to heat the surface of the steel part faster, and then spray water in time to cool it quickly. The purpose of surface quenching is to obtain high hardness and wear resistance on the surface of the part, while maintaining the high hardness of the core. Toughness and fatigue limits. Thin-walled parts should not be subjected to high frequency case hardening to avoid hardening.)

The above is the function and classification of metal heat treatment. If you want to know other news, you can consult us, and we will serve you wholeheartedly.