PRODUCTION OF LOW RELAXATION PC STEEL MATERIAL

• Main Authors: TAKEI MASAMITSU, KASHIWA FUMIAKI
• Format: Patent
• Language: English
• Published: 24.02.1992
• Subjects: CHEMISTRY; 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

PURPOSE:To produce a low relaxation PC steel material by subjecting a steel stock containing specific percentages of C and Si to rapid cooling and to heating under respectively specified conditions to apply primary tempering and strain and then carrying out secondary tempering by means of temp. rise under specific conditions. CONSTITUTION:A steel stock having a composition containing, by weight, <=0.4% C and 1.0-2.0% Si is cooled rapidly from a temp. not lower than the A3 transformation point down to a temp. not higher than the Ms point at a cooling velocity equal to or higher than critical cooling velocity, and heated up to 350-430 deg.C to undergo primary tempering and application of strain, and then, this steel stock is subjected to temp. rise up to a temp. between 430 and 480 deg.C and higher by >=20 deg.C than primary tempering temp. to undergo secondary tempering. By this method, the low relaxation PC steel material can be obtained, and further, the PC steel material excellent also in uniform elongation and straightness characteristics can be obtained.