Heat treatment industry often use heat-resistant steel castings.Heat treatment related to heat resistant steel castings basic common sense part 4:
4.tempering
Operation method: after quenching steel reheating to Ac1 below a certain temperature, the heat preservation, in air or oil, hot water, cooling water.
Objective: 1. Reduce or eliminate internal stress after quenching, reduce the workpiece deformation and cracking; 2. Adjust the hardness, and improve the plasticity and toughness, work for the required mechanical properties; 3. Stable workpiece size.
Application points: 1. Keep the steel after quenching and high hardness and wear resistance of low temperature tempering; While maintaining a certain toughness under the condition of elasticityand yield strength of steel with medium temperature tempering; To maintain the high impact toughness and plasticity, and of sufficient strength in high temperature tempering; 2. The general steel to avoid in the 230 ~ 280, stainless steel in 400 ~ 400 degrees between tempering, because at this moment can produce a temper brittleness.