Influence of gap on weld appearance in lap plasma arc welding of thin stainless steel plates

不锈钢薄板等离子弧搭接焊间隙对焊缝表面成形的影响 Influence of gap on weld appearance in lap plasma arc welding of thin stainless steel plates 李子晗 LI Zihan 1 first-author 忻建文 XINJianwen 1 吴东升 WU Dongsheng 1 张跃龙 ZHANG Yuelong 1 王欢 WANG Huan 2 华学明 HUA Xueming 1 corresp xmhua@sjtu.edu.cn 上海交通大学上海市激光制造与材料改性重点实验室 上海交通大学上海市激光制造与材料改性重点实验室 Shanghai Key Laboratory for Laser Manufacturing and Materials Modification, Shanghai Jiaotong University Shanghai Key Laboratory for Laser Manufacturing and Materials Modification, Shanghai Jiaotong University 沪东中华造船(集团)有限公司 沪东中华造船(集团)有限公司 Hudong-Zhonghua Shipbuilding(Group)Co., Ltd. Hudong-Zhonghua Shipbuilding(Group)Co., Ltd. 以液化天然气船薄膜型围护系统中304L不锈钢薄板等离子弧搭接焊为实际应用场景,使用示踪粒子检测和红外热成像技术对焊接过程中搭接间隙对熔池动态行为和焊缝表面成形的影响进行研究。示踪粒子检测结果表明,当间隙为0.3 mm或0.6 mm时,由于上板处的液态金属层很薄,容易凝固,最终在凝固区形成空洞;当间隙为0.9 mm时,上板熔化产生的液态金属在凝固区前聚集,但由于间隙较大,无法形成液桥,而是形成了一个金属液滴,最终形成驼峰。红外热成像的结果表明,随着间隙的增加,在熔池中部会形成一段低温区,高温区面积也有所增加,这与示踪粒子检测的结论一致。 Plasma arc welding is widely used to weld stainless steel, aluminum alloy, titanium and other materials due to its excellent welding adaptability. In this study, infrared thermography and particle tracing were used to investigate the molten pool dynamic behaviors and the weld appearance defects in lap plasma arc welding. The particle tracing results show that when the gap is 0.3 mm or 0.6 mm, the liquid metal layer on the top plate is very thin, which solidifies prematurely, and a void defect is formed at periphery. When the gap is 0.9 mm, a larger solidification zone is formed on the top plate. The liquid metal at the front part of molten pool flows backward. And then the liquid metal is blocked by the solidification zone and gathered in front of the solidification zone. However, due to the wider gap, it is difficult to form a liquid bridge and a droplet is formed. After the droplet solidifies, humping is formed. The infrared thermography results show that the increase of the gap will form a low temperature zone in the middle of the molten pool, and the area of the high temperature will also increase, which are consistent with the results obtained by particle tracing. 不锈钢薄板 等离子弧搭接焊 焊缝表面成形缺陷 示踪粒子检测 红外热成像 thin stainless steel plates lap plasma arc welding weld appearance defects particle tracing infrared thermography TG456.2 国家自然科学基金项目(52105324) 2022-03-08 12 51