Do you know the heat treatment process of powder metallurgy materials?Today, powder metallurgy materials are more and more widely used, and they have obvious advantages in replacing cast iron materials with low density, low hardness and strength.The heat treatment of powder metallurgy materials includes quenching, chemical heat treatment, steam treatment and special heat treatment.
1. Quenching and heat treatment process
Due to the existence of pores, powder metallurgy materials have lower heat transfer speed than tight materials, so the hardenability is relatively poor in quenching.In addition, when quenching, the sintering density of powder material is directly proportional to the thermal conductivity of the material.Due to the difference between sintering process and tight material, the uniformity of internal structure of powder metallurgy material is better than that of tight material, but there is a little inhomogeneity in the micro area. Therefore, the complete austenization time is 50% longer than the corresponding forging. When adding alloy elements, the complete austenization temperature will be higher and the time will be longer.
In powder metallurgy material of heat treatment, in order to improve the hardenability, usually add some alloy elements such as nickel, molybdenum, manganese, chromium, vanadium, etc., their role in the functional mechanism of dense materials are the same, can obviously refine grain, when its soluble in austenite increases the stability of the supercooled austenite, ensure the austenite transformation when the quenching, increase the surface hardness of the material after quenching, hardening depth increases.In addition, the powder metallurgy materials were then tempering after quenching treatment, the temperature control of the tempering treatment had a greater influence on the performance of powder metallurgy materials.