PRODUCTION OF PC STEEL EXCELLENT IN DELAYED BREAKDOWN CHARACTERISTIC AND MECHANICAL PROPERTY

• Main Author: TAKEI MASAMITSU
• Format: Patent
• Language: English
• Published: 25.10.1994
• Edition: 5
• Subjects: ALLOYS; CHEMISTRY; FERROUS OR NON-FERROUS ALLOYS; GENERAL DEVICES FOR HEAT TREATMENT OF FERROUS OR NON-FERROUSMETALS OR ALLOYS; MAKING METAL MALLEABLE BY DECARBURISATION, TEMPERING OR OTHERTREATMENTS; METALLURGY; METALLURGY OF IRON; MODIFYING THE PHYSICAL STRUCTURE OF FERROUS METALS; TREATMENT OF ALLOYS OR NON-FERROUS METALS

PURPOSE:To produce PC steel excellent in delayed breakdown characteristics and mechanical properties by subjecting a steel bar contg. specified amounts of C, Si, Ni, Nb, Mn, Cr, Mo, V, Ti and B to specified cooling and tempering, applying strains thereto and thereafter executing reheating. CONSTITUTION:Steel for a steel bar or a steel wire having a compsn. contg., as fundamental components, by weight, 0.20 to 0.40% C, 1.0 to 2.0% Si, 0.3 to 2.0% Ni and 0.01 to 0.15% Nb and furthermore contg. one or more kinds among 0.5 to 2.0% Mn, 0.05 to 0.50%, Cr, 0.01 to 0.15% Mo, 0.002 to 0.010% V, 0.01 to 0.05% Ti and 0.001 to 0.005% B, and the balance iron with inevitable impurities is subjected to rapid cooling from the A3 transformation point to the Ms point or below at the cooling rate of the critical cooling rate or above. Next, the steel bar or the like is temperted at a high temp. of >=400 deg.C, and strains are applied thereto in the process of the tempering stage. After the application of strains, it is reheated to a temp. higher than the tempering temp. by about 30 to 50 deg.C and is preferably held for >=5sec at >=350 deg.C.