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采用多层埋弧焊方法,研究了低合金钢焊缝人字裂纹。该裂纹的表面形态是:裂纹走向与焊缝纵向成45°角,并由焊缝柱晶界小段裂纹与穿柱晶小段裂纹连接成阶梯扩展途径,裂纹断口为韧窝或准解理。离子探针分析证实,锰、硫、磷、镍等元素与人字裂纹无直接联系;硅在断裂过程中析出:氢的增加有助于裂纹的产生。对人字裂纹的产生条件和形成机理作了探讨。提出人字裂纹断裂模型,屈服强度低于500N/mm~2的焊缝金属,在较大的塑性应变消耗和残余应力作用下,可能产生人字裂纹。
Using multi-layer submerged arc welding method, the low-alloy steel weld cracked herringbone was studied. The surface morphology of the crack is that the crack is oriented at a 45 ° angle to the longitudinal direction of the weld, and the small crack at the grain boundary of the weld joint is connected with the crack at the small crack through the column to be a ladder-shaped expansion way. The fracture is dimpled or quasi-cleaved. Ion probe analysis confirmed that manganese, sulfur, phosphorus, nickel and other elements and herringbone crack no direct contact; silicon precipitation during the fracture: the increase of hydrogen contribute to the generation of cracks. The formation conditions and forming mechanism of herringbone crack were discussed. The herringbone crack mode is proposed, and the weld metal with yield strength less than 500N / mm ~ 2 may produce herringbone crack under the effect of large plastic strain and residual stress.