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汽缸体及薄壁(<20毫米)铸件冷焊时,焊缝常因冷却速度大而产生气孔、熔合不良和段与段间衔接不好等缺陷。随着焊缝长度增加,使工件受热温度增高、焊缝变宽、热影响区增大,即使采用铸308焊条也可能产生裂缝。经长期摸索,我们在焊接过程中,用调节电流(边焊边减小电流)的方法,取得了良好的效果。对开坡口困难、壁厚较小(<8毫米)的汽车发动机的缸体或其它铸铁薄壁件可以不开坡口,采用这种减小电流的方法也是有效的。具体方法是:开始焊接时,电流比常规冷焊电流大1/3,随着焊缝长度的增加,使焊接电流减至常规电流的20%,其它焊接工艺与一般冷焊工
Cold-welded cylinder block and thin-walled (<20 mm) castings often result in defects such as porosity, poor fusion and poor connection between sections due to large cooling rates. As the weld length increases, the temperature of the workpiece increases, the weld becomes wider and the HAZ increases. Even the cast 308 welding rod may produce cracks. After long-term exploration, we have achieved good results by adjusting the current (reducing the current while welding) while welding. For the groove of the difficult, smaller wall thickness (<8 mm) of the engine block or other cast iron thin-walled parts can not groove, using this method to reduce the current is also effective. The specific method is: start welding, the current larger than the conventional cold welding current, with the increase of the weld length, the welding current is reduced to 20% of the conventional current, other welding processes and general cold welder