| 摘要 |
PURPOSE:To obtain the method which certainly exhibits the effect to improve residual stress with a heating means having small heat capacity, by forming a temp. distribution along an axial direction in the proper domains of the butt- welded circumferential joint of a hollow body at both sides of a weld line, and then spontaneously cooling them. CONSTITUTION:Specified positions in response to the size of pipes at both sides of a butt-welded circumferential joint 2 between pipes 1 and 1, e.g. domains in a distance of 10-30mm. or about 20-40mm. apart from a weld line in case of pipes made of steel SUS 304 having an outer diameter of about 100mm. and thickness of about 6mm., are selected. Said domains are annularly simultaneously heated by a heating means 3 such as a high-frequency induction heater to form high-temp. parts and a temp. distribution along its axial direction, and then spontaneously cooled while stopping the heating. Said heating may be performed to an extent enough to form the temp. distribution without the need to perform forcible cooling such as water cooling after or during the heating. Thus, the heating means is managed with small capacity. |
