| 摘要 |
PURPOSE:To prevent weld metal from cracking and to improve its toughness by providing a high-speed heating means in the rear of a welding electrode to heat the metal above the specific temperature at the specific heating speed. CONSTITUTION:In the case of performing the vertical welding on a Cr-Mo steel member 1 using the gas shielded arc welding electrode 2, the high-speed heating means 3 is arranged in the rear of the electrode 2 at the time of welding a last layer to heat the weld metal rapidly. At this time, the heating speed of a heating source 3 is made to >=200 deg.C/min and the weld metal is heated up too the temperature above an AC3 transformation point (720-800 deg.C). Since the last layer weld metal 4 is heated to raise the temperature rapidly up to a recrystallization temperature range of the extent of 800-950 deg.C, the occurrence of the cracking of the weld metal 4 is prevented and its structure is made fine. By this method, the occurrence of the cracking of the weld metal 4 is prevented and its toughness is improved.
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