quenching and high-temperature

Why should quenching and high-temperature tempering be carried out in the process of tempering and tempering of metal materials？
 
In the process of tempering and annealing of metal materials, quenching and high-temperature tempering are carried out for the following reasons:

1.Adjusting hardness and toughness: Quenching involves rapid cooling of the metal, resulting in a high hardness structure. However, high hardness often comes with brittleness. High-temperature tempering is performed to reduce the internal stresses and brittleness introduced during quenching, while increasing the toughness and ductility of the material.

2.Reducing stress and internal structure adjustment: Quenching introduces internal stresses that make the metal material unstable. High-temperature tempering helps reduce these stresses, improving the stability and reliability of the material. Additionally, tempering promotes the rearrangement of the crystal structure, allowing for internal structure adjustment and optimization.

3.Eliminating quenching brittleness: High hardness attained through quenching is often accompanied by brittleness, making the metal prone to fracture and damage. High-temperature tempering is carried out to lower the material's hardness, reduce brittleness, and improve its toughness and plasticity, enabling it to withstand external impacts and loads more effectively.

4、Refining grain structure: Quenching may result in the formation of coarse grains, which is detrimental to material properties. High-temperature tempering facilitates grain refinement through processes such as grain growth and recrystallization, enhancing the material's toughness and strength.
In summary, the application of quenching and high-temperature tempering in the heat treatment process allows for the adjustment of material hardness, toughness, and internal structure. It helps alleviate stress, eliminate brittleness, and refine grain structure to achieve metal materials with desired properties.