HEAT TREATMENT OF 13CRNI STAINLESS STEEL

摘要

PURPOSE:To prepare stainless steel having quality free from tempering brittleness and residual stress and excellent in strength characteristics, by applying tempering treatment of 15CrNi stainless steel after hardening treatment under a specific condition. CONSTITUTION:13CrNi stainless steel is hardened from a temp. of 1,050 deg.C to form a martensite structure having high strength and high hardness while the hardened steel is tempered to enhance toughness thereof. In performing this tempering treatment, said hardened steel is quenched in the vicinity of 550 deg.C to suppress the generation of tempering brittleness caused by the precipitation of Cr-carbide to a former austenite grain boundary. Succeedingly, the treated stainless steel is held once to a temp. range of 500-400 deg.C to prevent the generation of residual stress and, thereafter, gradually cooled to a room temp. By this method, the brittleness of the material due to gradual cooling and the generation of residual stress due to quenching can be together suppressed and 13CrNi stainless steel excellent in characteristics such as strength or toughness is obtained.