SA553/AISI304异种钢光纤激光自熔焊接头组织特征  

Microstructure Characteristics of Fiber Laser Autogenous Welding Joint of SA553 and AISI304 Dissimilar Steel

作　　者：卢舜 蔡艳[1,2] 信冬群 LU Shun;CAI Yan;XIN Dongqun(Shanghai Key Laboratory of Materials Laser Processing and Modification,Shanghai Jiao Tong University,Shanghai 200240,China;Collaborative Innovation Center for Advanced Ship and Deep-Sea Exploration,Shanghai 200240,China)

机构地区：[1]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200240 [2]高新船舶与深海开发装备协同创新中心,上海200240

出　　处：《热加工工艺》2021年第21期36-41,49,共7页Hot Working Technology

基　　金：上海市标准化推进专项项目(17DZ2202000)。

摘　　要：采用背面氮气托衬方式实现了10 mm厚SA553/AISI304异种钢板的光纤激光自熔焊。在偏焦量为0.5mm和0.8 mm时均获得较好的焊缝成形,偏焦量对焊缝横截面形貌和尺寸影响较小,焊缝均呈现“哑铃”形。观察发现,SA553/AISI304异种钢光纤激光焊焊缝金属的成分与组织并不均匀,液态金属在熔池上部和中下部各形成一个对流环,导致母材金属在熔池上部混合程度最弱。焊缝上部靠近SA553母材一侧的铬元素含量较低,焊缝下部的铬元素含量较高。偏焦量较小时,焊缝上部靠近SA553母材一侧为硬度较高的马氏体;偏焦量较大时,焊缝下部出现大量被马氏体包围的δ-铁素体,这两者均对接头低温性能不利。The fiber laser autogenous welding of 10 mm thick SA553 and AISI304 dissimilar steel plates was realized by using the nitrogen at backface.The qualified weld formation is obtained with focus offset distance of 0.5 mm and 0.8 mm.The size and morphology of cross section of weld seam is not sensitive to the offset.The cross section of weld seam is dumbbell shaped.The experimental results show that the chemical composition and microstructure of weld metal of SA553 and AISI304 dissimilar steel by fiber laser welding is inhomogeneous.The convection cell is formed by liquid metal in upper part and lower middle part of molten pool,which causes the weak mixing of base metal in the upper part of molten pool.The Cr element content in upper part of weld seam closed to SA553 is low.The Cr content in the lower part of the weld is higher.The martensite with higher hardness forms in the upper part of the weld near the SA553 base metal when the focus offset amount is small.A large amount ofδ-errite surrounded by martensite appears in the lower part of the weld when the focus offset amount is large.The two phenomena are harmful to low temperature performance of the welded joint.

关 键 词：异种金属 光纤激光焊 自熔焊 偏焦量 组织不均匀 

分 类 号：TG456.7[金属学及工艺—焊接]