We heat steel to a temperature of 30-50 degrees above the critical points Ac1 or Ac3, temper it, and cool it down quite quickly. As a result of this process, the strength and hardness of the steel increases while ductility decreases.
We heat it above the critical points Ac3 or Acm, temper it, and make subsequent cooling in air. This is done to obtain a uniform structure and to eliminate grout.
We heat the hardened steel to a temperature not higher than the temperature at the point Ac1, hold it at the given temperature and cool it, usually in the air. Tempering is the final operation of thermal treatment and is carried out to increase ductility, reduce internal stresses, stabilize the structure and dimensions of hardened parts.
We heat steel to a temperature of 30-50 degrees above the critical points Ac1 or Ac3, maintain it, and slowly cool it down together with the furnace. As a result of this type of processing, steel has a lower hardness and strength with sufficient ductility. Castings, forgings, and rolled products are annealed.
We perform chemical and thermal treatment, which consists of diffusion saturation of the surface layer of steel with carbon. The result is high surface hardness and wears resistance with a tough core.