WELD-CLOSED SHEAR REINFORCING BAR WITH HIGH STRENGTH

• Main Authors: TAKAHAMA TAKESHI, TAKEI MASAMITSU, IWAMOTO TAKASHI
• Format: Patent
• Language: English
• Published: 15.11.2002
• Edition: 7
• 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; MECHANICAL METAL-WORKING WITHOUT ESSENTIALLY REMOVINGMATERIAL; METALLURGY; METALLURGY OF IRON; MODIFYING THE PHYSICAL STRUCTURE OF FERROUS METALS; PERFORMING OPERATIONS; PUNCHING METAL; ROLLING OF METAL; TRANSPORTING; TREATMENT OF ALLOYS OR NON-FERROUS METALS

PROBLEM TO BE SOLVED: To provide a weld-closed shear reinforcing bar, which has high strength, high yield strength, and equivalent or rather superior characteristics of welded parts to the base material. SOLUTION: A method for manufacturing the reinforcing bar comprises hot rolling a steel material into a linear rod shape, which contains 0.8-2.0% Si, 0.8-2.0% Mn, 0.005-0.050% Al, 0.005-0.150% Nb, 0.0015-0.0150% N, further one or more of 0.05-2.00% Cr, 0.05-1.00% Mo, and 0.05-1.00% V, so as to make the total amount as 0.5% or more, then slowly cooling it to make the HMV hardness as 500 or less, quenching it in a predetermined condition, tempering it at a tempering temperature of 400-600 deg.C, cutting, bending, and welding both ends. The reinforcing bar has tensile strength of 1420 N/mm or higher, 0.2% yield strength of 1275 N/mm or higher, and butt elongation until fracture of 5% or more, without annealing the above material.