316L双层排水罩局部干法水下激光焊接接头组织演变及力学性能研究  

Microstructure Evolution and Mechanical Properties of 316L Joints Welded by Local Dry Underwater Laser with Double Layer Drainage

作　　者：张恒泉 周晓辉 魏连峰[1] 孙超[1] 龙绍军[1] 刘福运 檀财旺 宋晓国 Zhang Hengquan;Zhou Xiaohui;Wei Lianfeng;Sun Chao;Long Shaojun;Liu Fuyun;Tan Caiwang;Song Xiaoguo(Fourth Institute of Nuclear Power Institute of China,Chengdu 610213,Sichuan,China;Shandong Institute of Shipbuilding Technology,Weihai 264209,Shandong,China;Shandong Key Laboratory of Special Welding Technology,Harbin Institute of Technology at Weihai,Weihai 264209,Shandong,China)

机构地区：[1]中国核动力研究设计院,四川成都610213 [2]山东船舶技术研究院,山东威海264209 [3]哈尔滨工业大学(威海)山东省特种焊接技术重点实验室,山东威海264209

出　　处：《中国激光》2023年第12期50-59,共10页Chinese Journal of Lasers

摘　　要：采用自主搭建的双层排水罩局部干法装置对3 mm厚316L不锈钢进行激光焊接,对比陆地焊接条件研究了排水气压对焊接接头的影响,并基于优化的排水气压分析了水深对焊接接头成形及组织性能的影响,实现了表面成形美观、无气孔裂纹缺陷的焊缝。实验结果表明:在陆地条件下进行激光焊接时,焊缝内部无缺陷,接头抗拉强度可达595 MPa,拉伸试样断于母材处。通过Schaeffler相图及铬当量和镍当量计算,得出凝固焊缝组织由奥氏体和少量铁素体组成。当排水气压为0.3 MPa时,焊缝无法有效熔透,焊缝中易产生气孔缺陷,且焊缝内生成了魏氏奥氏体,接头的抗拉强度仅为347 MPa;随着排水气压增大至0.5 MPa,接头抗拉强度显著提高至584 MPa。当水深较大时,由于冷却速度过快,焊缝中易生成脆性的魏氏奥氏体,弱化了接头的力学性能。与陆地条件相比,水下焊接时焊缝中形成了明显的树枝晶,且枝晶宽度在35 mm水深时减小至26.5μm。当水深增大至35 mm时,接头的强度和塑性有所下降,试样断于焊缝处,韧窝尺寸较小,试样的变形能力较差。水下激光局部干法焊接及修复具有较好的可行性和较为广阔的应用前景。Objective Welding technology is essential for equipment assembly and repair in nuclear-power engineering.To reduce the influence of nuclear radiation,it is necessary to perform underwater welding and repair of in-service nuclear power facilities.Commonly used methods include argon tungsten arc and laser welding.Owing to the long transmission distance and good accessibility of laser welding,it has application significance.Underwater welding is divided into wet,dry,and local dry methods.The local dry method exhibits good quality,low cost,and good prospects.Therefore,in this study,underwater local dry equipment is designed and developed to evaluate the influence of laser welding parameters on the microstructure and properties and to provide technical guidance for underwater welding and repair of nuclear power equipment.Methods In this study,independently designed double-layer drainage was used in the local dry underwater laser welding of 316L stainless steel with a thickness of 3 mm.First,the appropriate welding parameters were obtained on land,and the influence of the drainage air pressure on the welding quality was explored under these laser welding parameters.Finally,the welding quality at different water depths was evaluated,and the weld seam forming quality,microstructure distribution,microstructure evolution,and mechanical properties of the joint were analyzed.Results and Discussions In terms of the weld formation,compared with welding on land,the effective heat input was decreased owing to insufficient drainage under a low drainage air pressure of 0.3 MPa and a water depth of 35 mm.Thus,the base material hardly melted under these parameters(Fig.3),and pores were found in the weld(Fig.4),resulting in unstable weld surface formation.With an increase in water depth,the area of the fusion zone was reduced to 4.7 mm2.In terms of the microstructure,typical austenite andδ-ferrite were formed in the weld(Fig.7),which is consistent with the Schaeffler diagram(Fig.6).Compared with observations for welding on land,evid

关 键 词：激光技术 不锈钢 水下局部干法 微观组织 力学性能 

分 类 号：TG456.7[金属学及工艺—焊接]