X70管线钢熔合区裂纹与焊接工艺的关系 孙咸

探讨了X70管线钢中熔合区裂纹与焊接工艺的关系。结果表明，在铁研试件中出现的沿熔合线分布的裂纹属于氢致冷裂纹。当冷裂纹三要素集中于X70管线钢熔合区的粗晶区时，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。焊接工艺与裂纹的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。

Relationship between cracking in the fusion zone and welding process of X70 pipeline steel

Relationship between cracking in the fusion zone and welding process of X70 pipeline steel was discussed. The results showed that the crack properties distributed along the fusion zone appearing in the slit cracking specimens are hydrogen-induced cold cracks. The area had become the weak link of the joint when the coarse-grained zone of the fusion zone of X70 pipeline steel had the cold crack three factors, so cracks easily formed in the area. The microstructure characteristics of fusion zone are the necessary condition of the cracks to form in the influencing factors, and the stress level and distribution characteristics of hydrogen are the sufficient conditions. The relationship between the welding process and cracking essentially reflects the relationship between hydrogen, stress and crack in weld metal. 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.