MANUFACTURE OF HIGH-STRENGTH BOLT

• Main Authors: NISHIO HARUTAKA, NAKAMURA SADAYUKI, KIMURA TOSHIMITSU
• Format: Patent
• Language: English
• Published: 28.02.1995
• Edition: 6
• 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 prolong the life of header tool and provide a manufacturing method of a high-strength bolt by heating just before processing a high-strength alloy steel wire rod which is manufactured by cooling control and aging treatment after hot rolling with a header and forming it. CONSTITUTION:The alloy steel consisting of 0.15-0.35% C, 0.05-1.5% Si, 0.8-2.5% Mn, 0.1-1.5% Cr, 0.1-0.5% Mo, 0.05-0.30% V, and >=1 kind of 0.03-0.30% Nb and 0.02-0.20% Ti and the balance Fe essentially is made into the wire rod by hot rolling. In its cooling process, the wire rod is cooled from 800 deg.C down to 600 deg.C for <=50sec, successively cooled to <=400 deg.C and aging tratment is executed at 500-650 deg.C for >=10min. The wire rod is heated and held at 400-600 deg.C for 10sec just before processing with the bolt header, processed with the header and, after that, cooled to <=250 deg.C at a cooling rate of 20 deg.C/min.