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采用超声冲击技术对Q370qE桥梁钢焊接接头进行了全覆盖超声冲击处理(UIT),并通过扫描电镜等对UIT前后焊接接头的显微组织的变化进行了观察和分析。结果表明,原始Q370qE焊接接头微观组织特征为:焊缝区铸态枝晶组织发达,熔合区与热影响过热区均呈较粗大的贝氏体组织,且熔合区存在少量直径约25μm的不规则圆形缩孔等缺陷,热影响正火区为较细的等轴晶铁素体+珠光体组织;经过UIT后,焊接接头在高频和强烈的机械冲击力作用下,原有表面锈层被去除干净,下表层的新鲜金属产生了厚约100～200μm的致密塑性变形层,形成了大致平行于焊缝表面的非常细密的形变织构,并分析讨论了该组织结构的形成机理。
Ultrasonic impact technique was used to test the full coverage ultrasonic welding (UIT) of Q370qE steel welded joints. The changes of the microstructures of welded joints before and after UIT were observed and analyzed by SEM. The results show that the microstructure of the original Q370qE welded joint is characterized by that the as-cast dendritic structure is developed in the weld zone and the coarser bainite structure appears in both the fusion zone and the heat affected zone. There are also a few irregularities Round shrinkage and other defects, the heat affected zone is fine equiaxed ferrite + pearlite organization; after UIT, the welded joints in high frequency and strong mechanical impact under the effect of the original surface rust layer Was removed and the fresh metal in the bottom layer produced a dense plastic deformation layer with a thickness of about 100-200 μm. A very fine deformable texture approximately parallel to the weld surface was formed, and the formation mechanism of the structure was analyzed.