In production, annealing is a commonly used preparatory heat treatment process. It can eliminate internal stress and component structure heterogeneity in castings and forgings, improve and adjust the mechanical properties of steel, and prepare the structure for the next process.

Steel annealing is to heat the steel to an appropriate temperature, maintain it for a certain period of time, and then slowly cool it to make the steel close to the equilibrium structure.

Its purpose is to make the chemical composition uniform, improve mechanical properties and process performance, eliminate or reduce internal stress, and prepare the parts for final heat treatment.

Steel quenching and tempering is a very important heat treatment process with a wide range of applications. Hardening significantly increases the strength and hardness of steel.

If combined with tempering at different temperatures, the internal stress of quenching can be eliminated, and at the same time, a combination of strength, hardness, and toughness can be obtained to meet different requirements.

Therefore, quenching and tempering are inseparable heat treatment processes.

Steel quenching

Quenching hardening is a heat treatment in which the steel is heated above the critical point, and after heat preservation, the martensite or lower bainite structure is obtained when the steel is above its critical cooling rate (Vc).

Tempering

Tempering is the next heat treatment process of quenching. It also determines the structure and performance of the steel in use and is related to the service life of the workpiece.

Its main purpose is to reduce or eliminate quenching stress, ensure the corresponding structural transformation, and stabilize the size and performance of the workpiece; improve the thermoplasticity and thermal properties of steel, select different tempering temperatures, and obtain appropriate hardness, strength, plasticity, or toughness, so as to Meet the performance requirements of different workpieces.

There are four major differences between normalizing and annealing:

(1) The higher the normalizing temperature, the lower the annealing temperature;

(2) Normalizing has a faster cooling rate than annealing;

(3) The use effect is different. After carburizing and normalizing treatment, the reticular cementite is removed, but not after annealing;

(4) The normalizing cycle is short and easy to operate; the annealing cycle is long and the operation is cumbersome.

Different inductive heating requires different process equipment to be used together. Correct use and operation can achieve twice the result with half the effort.