基于铁研试验的X80钢焊接裂纹倾向探讨

Discussion on the tendency of welding crack of X80 steel based on slit type cracking test

探讨了铁研试验中涉及的X80钢焊接裂纹倾向。结果表明,X80管线钢试样断面裂纹率随工件预热温度的提高而减小。启裂于根部应力集中处、沿熔合区扩展裂纹的性质属于氢致冷裂纹。当冷裂纹三要素集中于X80管线钢熔合区粗晶区时,该区成为接头的薄弱环节,极易形成裂纹。在裂纹影响因素中,熔合区组织特性是裂纹产生的必要条件,应力水平和氢的分布特征则是充分条件。焊接工艺与裂纹关系实质上反映的是焊缝中氢和应力与裂纹间的关系。工程上常用焊缝中残留的扩散氢量最小化、不足以引发氢致冷裂纹的"焊缝金属低氢化"综合工艺,并获得了满意的效果。

The tendency of welding cracks of X80 steel involved in the slit type cracking test was discussed. The results show that the section crack rate of X80 pipeline steel decreases with the increase of the preheating temperature of the workpiece,the shape and nature of cracks that are cracked at the root stress concentration and distributed along the fusion zone are hydrogen-induced cold cracks. The area has become the weak link of the joint when the cold crack three factors are focused on the coarse-grained zone of the fusion zone of X80 pipeline steel,so it is easy to form cracks on the area. The microstructure characteristics of fusion zone are the necessary condition of the cracks to form in the influencing factors,the stress level and distribution characteristics of hydrogen are sufficient conditions. The relationship between the welding process and cracking essentially reflects the relationship between hydrogen,stress and crack in weld metal. The comprehensive processes of low hydrogenation with minimizing residual diffusion hydrogen in the weld metal and insufficient to cause hydrogen-induced cold cracks are often used in engineering,and have achieved satisfactory results.