METHOD FOR TEMPERING GAS PRESSURE WELDING SECTION AND METHOD FOR BONDING STEEL BAR

摘要

PROBLEM TO BE SOLVED: To improve both characteristics even if a gas pressure welding section causes embrittlement and both tensile and bonding characteristics are deteriorated. SOLUTION: A welding bulge section generated at the time of gas pressure welding steel bar is tempered. When tempering is performed, the welding bulge section which is cooled below the transformation expiry temperature (for instance, reheating at 750-900 deg.C) is re-heated, and the re-crystallized section A which shows 235-320 Hv in Vickers hardness test is so designed to be 10-60% volume of the bulge section.