不同焊接方法的BR1500HS高强钢接头淬火前后的组织和力学性能研究  

Add to Favorite Get Latest Update Microstructure and Mechanical Properties of BR1500HS High Strength Steel Joints Welded by Different Welding Methods before and after Quenching

作　　者：马荣飞 朱春东[1,2,3] 周联谱 石磊 夏曦 MA Rongfei;ZHU Chundong;ZHOU Lianpu;SHI Lei;XIA Xi(School of Material Science and Technology,Wuhan University of Technology,Wuhan 430070,China;Hubei Center for Quality Inspection of Special Purpose Vehicles,Suizhou 441300,China;Suizhou-WUT Industry Research Institute,Suizhou 441300,China)

机构地区：[1]武汉理工大学材料科学与工程学院,湖北武汉430070 [2]湖北省专用汽车质量检测中心,湖北随州441300 [3]随州武汉理工大学工业研究院,湖北随州441300

出　　处：《热加工工艺》2023年第5期30-35,共6页Hot Working Technology

基　　金：随州市新能源、轻量化、智能化关键核心技术研发项目(随科发﹝2019﹞9号)。

摘　　要：分别采用光纤激光填丝焊和混合气体保护焊,使用ER70-G焊丝对3.5 mm厚的BR1500HS高强钢板进行对接焊试验。将试样加热到900℃保温5 min后水淬,对淬火前后的焊接接头进行拉伸测试、硬度测试和焊缝的宏观形貌、微观组织研究。使用场发射扫描电子显微镜对接头的断口形貌进行分析。结果表明:淬火前两种焊接方法的接头强度都超过了母材的,淬火后激光焊接头的强度显著高于气体保护焊的,最高达到1805 MPa。淬火前激光焊焊缝区和热影响区已经生成了大量的马氏体和少量的贝氏体,显微硬度达到了430 HV,气体保护焊的焊缝区和热影响区组织主要由贝氏体和珠光体及部分铁素体组成,显微硬度只有380 HV。淬火后两种焊接方式的焊缝区和热影响区组织都是马氏体和残余奥氏体,但是激光焊接头的马氏体含量更高,其焊缝区显微硬度更高。淬火后气体保护焊接头断口为塑性韧窝断口,激光焊接头断口为准解理断口,气体保护焊接头强度低但塑性更好。The butt welding tests of 3.5 mm thick BR1500HS high-strength steel plate were carried out by using fiber laser wire-filling welding and mixed gas shielded welding with ER70-G welding wire,respectively.The samples were heated to900℃and held for 5 min,then quenched in water.The tensile test and hardness test of the welded joints before and after quenching were carried out,and the macroscopic morphology and microstructure of the welds were studied.Field emission scanning electron microscope was used to analyze the fracture morphology of the welded joint.The results show that the joint strength of the two welding methods before quenching exceeds the base metal strength,and the strength of laser welded joint after quenching is significantly higher than that of gas shielded welding with the maximum of 1805 MPa.Before quenching,a large amount of martensite and a small amount of bainite are generated in the weld zone and heat-affected zone of laser welding,and the microhardness reaches 430HV.While the microstructure of the weld zone and heat-affected zone of gas shielded welding mainly consists of bainite,pearlite and a part of ferrite,and the microhardness is only 380 HV.After quenching,the weld zone and heat-affected zone microstructure of the two welding methods are both martensite and residual austenite,but the martensite content of the laser welding joint is higher and the microhardness of the weld zone is higher.After quenching,the fracture of gas shielded welding joint is plastic dimple fracture,and the fracture of the laser welding joint is quasi-cleavage fracture.The strength of gas shielded welding joint is lower but the plasticity is better.

关 键 词：激光填丝焊 混合气体保护焊 超高强钢 淬火 强度 

分 类 号：TG142.2[一般工业技术—材料科学与工程] TG457.11[金属学及工艺—金属材料]