超声冲击对Q370qE钢焊接接头组织结构的影响

Effects of Welding Parameters on Microstructure and Properties of Q370qE Welded Joint

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。

The welded joint of Q370qE steel plate was treated by ultrasonic impact treatment（UIT）.The surface microstructure of the untreated and treated specimens was investigated by SEM.The results show that the typical casting dendrite structure of the weld seam,a spot of shrinkage cavity and the growth grain of the fusion zone and the fine grain of the heat affected zone are the metallographic structures character of Q370qE steel welded joints before UIT.After being UIT,the welded joint forms strong plastic deformation on the surface layer because of ultrasonic impact effect.The depth of the plastic deformation layer is dense laminar structure,which is about 100 μm～200 μm from the surface.The forming mechanism of the microstructure was discussed.