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(2)在补焊部位局部预热250℃～400℃,降低热影响区的淬硬倾向,防止冷裂.(3)以直流反接极性、短弧进行焊接.焊接线能量应稍大,以使其热影响区的冷却速度减缓,但电流不能太大,以免使焊条发红.(4)补焊时应堆高4～8mm.收弧时要填满弧坑,以免出现火口裂纹.(5)焊后进行局部保温及缓冷处理,减少或消除残余应力,改善接头显微组织,并加速焊缝中的氢向外扩散,有利于防止产生冷裂纹.修复后的滚压模膛经生产检验,补焊部分未产生裂纹及脱落现象.
(2) Partial preheating 250 ℃ ~ 400 ℃ in the repaired area to reduce the harden tendency of heat affected zone and prevent cold cracking. (3) Welding with reverse polarity and short arc of DC, the welding line energy should be slightly larger , So that the heat-affected zone cooling rate slowed down, but the current can not be too large, so as not to make the electrode red. (4) Replenishment should heap height 4 ~ 8mm. Arc filling crater to fill to avoid crater cracks . (5) Local heat preservation and slow cooling after welding, reduce or eliminate residual stress, improve joint microstructure and accelerate diffusion of hydrogen in welding seam, which will help prevent the generation of cold crack. After the production test, repair welding parts did not produce cracks and shedding phenomenon.