车用超高强钢22MnB5及22MnB5-Q235光纤激光焊接接头组织及性能的研究  

Microstructure and Properties of Fiber Laser Welded Joints of Motor Ultrahigh-Strength Steel 22MnB5 and 22MnB5-Q235

作　　者：贾进[1] 杨尚磊[1,2] 倪维源 白建颖[1] 丁波[1] 

机构地区：[1]上海工程技术大学材料工程学院,上海201620 [2]上海工程技术大学高强激光智能加工装备关键技术产学研开发中心,上海201620

出　　处：《中国激光》2014年第10期49-55,共7页Chinese Journal of Lasers

基　　金：国家自然科学基金(51075256);上海市教育委员会科研创新重点项目(11ZZ177);上海市激光制造与材料改性重点实验室(上海交通大学)开放课题(MLPM2012-1)

摘　　要：为了提高车用超高强钢激光焊接技术的发展,采用光纤激光器对1.9mm厚的22MnB5钢板进行激光对焊以及22MnB5与Q235钢板的激光拼焊。研究了激光焊接接头的微观组织、硬度以及拉伸性能的变化,分析了焊接速度对接头组织、性能的影响。结果表明,22MnB5钢焊缝组织主要是板条马氏体,22MnB5热影响区可分为完全淬火区、不完全淬火区和回火区,而Q235热影响区不存在回火区。焊接接头硬度分布不均匀,在焊缝边缘硬度最高。热影响区很窄,硬度急剧下降,22MnB5热影响区存在严重的软化区,最低硬度仅为319.6HV,Q235热影响区不存在软化区。随着焊接速度的增加,焊缝组织变得细小,马氏体含量增多,当焊速达到5m/min时,22MnB5焊缝最高硬度达到544.2HV。在垂直于焊缝的负载下,焊接速度为3～5m/min时,22MnB5拉伸试样均断裂在热影响区,塑性较差,断后延伸率仅为2%左右,而母材的断后延伸率却达到了8.9%。To accelerate the development of the laser welding technology of advanced high strength steel（AHSS）,similar butt welding of 1.9 mm thick 22MnB5 and dissimilar tailored blank welding of 22MnB5 and Q235 are performed by using a fiber laser.The microstructure,hardness and tensile properties of weld joints are analyzed after the fiber laser welding（FLW）.The results show that the microstructure of weld zone（WZ）mainly contains lathy martensite.Heat affected zone（HAZ）in 22MnB5 can be divided into three parts：quenched zone,incomplete quenched zone and tempered zone,and the last one is absent in Q235.The hardness distribution of weld joints is nonuniform,and the weld edge has the highest hardness.HAZ is very narrow and a soft zone exists in the 22MnB5 HAZ with the lowest hardness of 319.6 HV,while there is no soft zone in Q235.With the increase of welding speed,the martensite in WZ becomes finer,leading to the increasing of hardness.When the welding speed is 5 m/min,the highest hardness of the WZ attains 544.2 HV which is the highest of all the samples.The 22MnB5 samples for tensile test which are welded at the speed from3 to 5 m/min are all broken in HAZ,and the elongation at break is only about2%,which is obviously worse than that of base metal（8.9%）.

关 键 词：激光技术 超高强钢 22MnB5 激光焊接 微观组织 力学性能 

分 类 号：TG456.7[金属学及工艺—焊接]