不同强度级别双相不锈钢激光焊接头的组织与力学性能  

Microstructure and Mechanical Properties of Laser Welded Joints of Duplex Stainless Steel with Different Strength Grades

作　　者：谭海林[1] 赖春明 周家林[2] 莫金竹 聂慧 TAN Hailin;LAI Chunming;ZHOU Jialin;MO Jinzhu;NIE Hui(Hunan Chemical Vocational Technology College,Hunan Zhuzhou 412011,China;Key Laboratory for Ferrous Metallurgy and Resources Utilization of Ministry of Education,Wuhan University of Science and Technology,Wuhan 430081,China;Zhuzhou Tianyi Welding&Cutting Automatic Equipment Co.,Ltd.,Hunan Zhuzhou 412000,China)

机构地区：[1]湖南化工职业技术学院,湖南株洲412011 [2]武汉科技大学钢铁冶金及资源利用省部共建教育部重点实验室,武汉430081 [3]株洲天一自动焊接装备有限公司,湖南株洲412000

出　　处：《精密成形工程》2024年第6期122-128,共7页Journal of Netshape Forming Engineering

基　　金：湖南省教育厅科学研究项目(23B0966);湖南省自然科学基金(2022JJ60042)。

摘　　要：目的为了合理制定不同强度等级DP钢同种和异种接头的激光焊接工艺,研究激光焊接工艺对接头组织性能的影响。方法采用SEM、硬度试验、拉伸试验等手段,研究不同强度等级DP钢同种和异种激光焊接接头的微观组织和力学性能。结果对于同种DP钢激光焊接,由于接头各个区域经历的热循环不同,因此其马氏体体积分数和形态、含碳量等存在明显差异。在焊缝熔合区,由于冷却速度较高,因此马氏体体积分数较高且为细条状,硬度高于母材硬度。在热影响区,由于马氏体发生了回火分解,因此其硬度值低于母材硬度,且软化的程度和范围大小与DP钢的强度级别相关。软化的热影响区成为接头的薄弱区域,降低了接头的拉伸性能。在异种DP钢激光焊接接头中,焊缝熔合区的硬度也明显高于母材硬度。靠近高强度级别母材侧的热影响区范围更大,软化程度更明显,接头硬度分布不再对称。接头的抗拉强度与低等级DP钢母材的抗拉强度基本一致。结论激光焊接工艺对不同强度等级DP钢同种和异种接头组织性能的影响存在较大的差异,DP钢强度级别越高,接头或接头对应侧的热影响区软化程度越明显,这在制定焊接工艺以及焊后处理工艺过程中需要予以考虑。The work aims to understand the effect of laser welding process on the microstructure and properties of welded joints to formulate the laser welding process for joints of similar and dissimilar DP steel with different strength grades.The mi-crostructure and mechanical properties of laser welded joints of DP steel with different strength grades were studied by means of SEM,hardness and tensile testing.For laser welding of similar DP steel,the volume fraction of Martensite,the existing mor-phology and carbon content in each area of the joint were significantly different due to different thermal cycles.In the weld fu-sion zone,due to the high cooling rate,the volume fraction of Martensite was high and it was thin strip,and the hardness was higher than that of the base metal.In the heat affected zone,due to tempering decomposition of Martensite,the hardness was lower than that of the base metal,and the degree and range of softening were related to the strength level of DP steel.The sof-tened heat affected zone became the weak area of the joint,reducing its tensile performance.In the laser welded joints of dis-similar DP steels,the hardness of the weld fusion zone was also significantly higher than that of the base metal.The heat af-fected zone near the side of the high strength base metal was larger,and the softening degree was more obvious,which made the hardness distribution of the joint no longer symmetrical.The tensile strength of the joint was basically consistent with the base material of low grade DP steel.In conclusion,the influence of laser welding process on the microstructure and properties of DP steel joints with different strength grades is quite different.The higher the strength grade of DP steel is,the more obvious the softening degree of the heat affected zone on the joint of the corresponding side of the joint is.This needs to be taken into ac-count in the development of welding process and post weld treatment process.

关 键 词：双相不锈钢 激光焊接 显微组织 力学性能 马氏体体积分数 

分 类 号：TG456.7[金属学及工艺—焊接]