FV520B钢激光打底焊结合CMT填充焊焊接接头的组织和性能  

Microstructures and Properties of FV520B Steel Joint by Laser Backing Welding with CMT Filler Welding

作　　者：邓德伟[1,2] 吕捷 马玉山 张勇[2] 黄治冶 Dewei Deng;Jie Lü;Yushan Ma;Yong Zhang;Zhiye Huang(School of Materials Science and Engineering,Dalian University of Technology,Dalian,Liaoning 116024,China;Shenyang Blower Works Group Corporation,Shenyang,Liaoning 110869,China;Wuzhong Instrument Co.,Ltd.,Wuzhong,Ningxia 751100,China)

机构地区：[1]大连理工大学材料科学与工程学院,辽宁大连116024 [2]沈阳鼓风机集团股份有限公司,辽宁沈阳110869 [3]吴忠仪表有限责任公司,宁夏吴忠751100

出　　处：《中国激光》2020年第11期33-43,共11页Chinese Journal of Lasers

基　　金：辽宁重大装备制造协同创新中心基金(DUT2017031);高端控制阀产业技术协同创新中心基金(2018WZ003)

摘　　要：采用激光焊打底和冷金属过渡(CMT)焊填充的工艺对FV520B钢进行焊接,研究了不同工艺参数下接头的组织和性能。激光打底焊后,焊缝熔化区的组织主要包括原奥氏体晶粒内平行排布的板条马氏体以及分布于原奥氏体晶界和马氏体板条界的δ铁素体;激光焊熔合线位置存在呈连续和离散状分布的δ铁素体。随着CMT填充焊热输入的增加,熔宽、熔深及热影响区的宽度均增加,激光打底焊热影响区和熔化区的组织特征逐渐消失;当CMT填充焊的热输入较低时,在紧靠填充焊熔合线的受热影响的激光焊熔化区(HALWFZ)内,晶粒在高温热影响下变为等轴状,并且随着到熔合线距离的增加而变小;当热输入量较高时,激光焊熔化区的柱状晶组织均转变为等轴晶且晶粒较大。与激光焊相比,填充焊后焊缝横截面在水平方向各区域的硬度分布更加均匀;随着填充焊热输入增加,HALWFZ的平均硬度先增大后减小。填充焊熔化区(FWFZ)的平均硬度低于激光焊熔化区(LWFZ);LWFZ在靠近熔合线处的硬度最低。填充焊后激光焊区域的强度大于母材,填充焊区域的强度小于母材。随着填充焊热输入增加,激光焊区域的冲击韧性增加。电化学腐蚀试验表明,随着热输入增加,LWFZ的腐蚀电位先升高后降低;填充焊前和填充焊后LWFZ的耐蚀性均高于母材。Herein,an FV520B steel joint is formed through laser backing welding and cold metal transfer(CMT)filler welding.Microstructures and properties of the joints at different processing parameters are studied.Microstructures of the fusion zone(FZ)obtained using laser backing welding mainly comprise lath martensites,which are arranged in a parallel form in the primary austenite grains,andδferrites,which are situated at the primary austenite grain boundaries and lath martensite interfaces.Some continuous and discreteδferrites are located at the fusion line of laser welding.The weld width,weld penetration,and the width of heat-affected zone(HAZ)increase with the increase of the heat input of the CMT filler welding.Moreover,the microstructural characteristics of the HAZ and FZ of laser backing welding gradually disappear.When the heat input of CMT filler welding is lower,the grains in the heat-affected laser welding fusion zone(HALWFZ)close to the filler welding fusion line exhibit an equiaxed shape because of the high temperature reheating.Furthermore,the size of the equiaxed grains decreases with the increase of distance to the filler welding fusion line.When the heat input of CMT filler welding is higher,the columnar grain microstructures in the laser welding fusion zone transfer into the larger equiaxed grains.Compared with the single laser welding,the hardness of the weld cross-section exhibits more uniform distribution in the horizontal direction after the filler welding.With the increase of heat input of filler welding,the average hardness of HALWFZ initially increases and then decreases.The average hardness of the filler welding fusion zone(FWFZ)is lower than that of the laser welding fusion zone(LWFZ).Moreover,the average hardness of the LWFZ presents the lowest value in the vicinity of the filler welding fusion line.After filler welding,the strength of laser backing welding area is higher than that of the base metal,whereas the strength of filler welding area is lower than that of the base metal.The impact tou

关 键 词：激光技术 激光材料加工 激光打底焊 CMT 力学性能 耐蚀性 

分 类 号：TG456[金属学及工艺—焊接]