组合焊缝对中碳合金钢焊接裂纹的影响

Effect of Combined Weld on Weld Crack of Medium-carbon Alloy Steels

采用Y形坡口裂纹试验和显微分析方法,研究了三种不同的组合焊缝对中碳合金钢焊接裂纹的影响。结果表明,底层焊道熔合区裂纹为氢致延迟裂纹;底层焊条的合金系统对该裂纹的生成有一定的影响;底层焊道熔合区的马氏体和氢的富集以及大的拘束应力,是裂纹生成的必要和充分条件;提出了防止裂纹产生的实用工艺。

The effects of three kinds of combined weld on the weld crack of medium-carbon alloy steels are studied by using slit type cracking test and microscopic analysis method. The results show that the bond crack in backing weld is hydrogen-induced crack. To a certain extent the alloy system of bottom runs can influence the occurrence for this kind of crack. The martensite structure and hydrogen diffusion in fusion zone of backing weld and great restraint stress of welded joint is necessary and sufficient conditions of crack occurrence. A usefull and practical process that can prevent weld metal from cracking is put forward, too.