研究外加交变电磁场对SUS316L奥氏体不锈钢激光填丝窄间隙焊接接头宏观成形、铁素体-奥氏体微观组织、接头力学行为及耐蚀性的影响,结果表明:交变电磁场能够实现焊丝在焊缝横向位置的可控熔化行为,使窄间隙焊接接头的熔宽增加,熔深减小,焊缝对称性提高,而且接头中的未熔合及气孔缺陷也得到了抑制。外加交变电磁场将振动能量直接引入到焊接熔池中,改变了熔池原有的自然对流模式,促使熔池中心的高温液态金属向坡口侧壁润湿铺展,改善焊缝成形;同时,熔池的搅拌作用使焊缝温度均匀,降低了熔池的温度梯度,抑制了粗大奥氏体柱状晶的生长,增加了晶粒取向的多样性。电磁场辅助焊接接头焊缝晶粒尺寸细小,枝晶间距较小,枝晶形态交错复杂。接头拉伸试验和电化学腐蚀试验表明,电-磁场辅助SUS316L不锈钢窄间隙焊接接头具有良好的的力学性能和和耐蚀性。

This study investigates the effects of an external alternating electromagnetic field on the joint formation, ferrite-austenite microstructure, mechanical properties, and corrosion resistance of SUS316L austenite stainless steel narrow-gap laser hot-wire feeding welded joint. The experimental results show that the controlled melting of the filler wire in a transverse direction is achieved by the alternating electromagnetic field. The joints with wider width, shallower penetration and highly symmetric weld are obtained, in addition, non-fusion and pore defects in the joints are also suppressed. The external alternating electromagnetic field introduces vibration energy into the weld pool, thereby changing the original natural convection mode of the weld pool and promoting a high-temperature liquid metal flow from the weld center to the groove sidewall. The stirring effect of the molten pool makes the temperature uniform, decreases the temperature gradient of the molten pool, inhibits the growth of coarser austenite columnar crystals, and increases the grain orientation diversity. The electromagnetic field-assisted welds have small grain size and dendritic spacing as well as a complex dendrite morphology. In summary, the joint tensile and electrochemical corrosion tests show that the electromagnetic field-assisted SUS316L stainless steel narrow-gap welded joint has good mechanical properties and corrosion resistance.