The purpose of normalizing: can eliminate the overheated coarse grain structure and Weiss structure of the casting, forging, and welding, the band structure in the rolled material; refine the grain; and can be used as pre-heat treatment before quenching. It can eliminate reticulate cementite and refine pearlite, which not only improves mechanical properties, but also facilitates subsequent spheroidizing annealing. Free cementite at grain boundaries can be eliminated to improve its deep drawing performance.
Then quenching: quenching is to heat and keep the workpiece warm, and then quickly cool it in water, oil or other inorganic salts, organic aqueous solutions and other quenching media. After quenching, the steel becomes hard, but at the same time becomes brittle.
The purpose of quenching: to improve the mechanical properties of metal materials or parts.
The last is tempering: in order to reduce the brittleness of the steel parts, the tempered steel parts are kept at a suitable temperature higher than room temperature but lower than 710 ° C for a long time and then cooled. This process is called tempering. fire.
The purpose of tempering: to reduce internal stress and reduce brittleness, there is a lot of stress and brittleness in the quenched parts, if there is no timely tempering, it will often cause deformation or even cracking. Adjust the mechanical properties of wheel forgings. After quenching, the workpiece has high hardness and brittleness. In order to meet the different performance requirements of various workpieces, tempering can be used to adjust hardness, strength, plasticity and toughness. Stable workpiece size. Through tempering, the metallographic structure can be stabilized to ensure that it will no longer deform during subsequent use. Improve the cutting performance of certain alloy steels.