球墨铸铁QT500与合金钢20MnCr5同轴双激光焊接工艺及组织性能研究  

Study on Coaxial Dual-Beam Laser Welding Process and Microstructure and Properties of Nodular Cast Iron QT500 and Alloy Steel 20MnCr5

作　　者：陈帅帅 张文东 刘祥环[2] 陈启云 李博洋 崔双好 刘黎明[1] 王红阳[1] Chen Shuaishuai;Zhang Wendong;Liu Xianghuan;Chen Qiyun;Li Boyang;Cui Shuanghao;Liu Liming;Wang Hongyang(Liaoning Provincial Key Laboratory of Advanced Connection Technology,School of Materials Science and Engineering,Dalian University of Technology,Dalian 116024,Liaoning,China;Zhuzhou Gear Co.,Ltd.,Zhuzhou 412000,Hunan,China)

机构地区：[1]大连理工大学材料科学与工程学院辽宁省先进连接技术重点实验室,辽宁大连116024 [2]株洲齿轮有限责任公司,湖南株洲412000

出　　处：《中国激光》2024年第16期12-20,共9页Chinese Journal of Lasers

基　　金：国家自然科学基金(52375308,51975090)。

摘　　要：针对球墨铸铁与合金钢异种材料焊接界面容易形成碳偏聚进而产生裂纹的问题,通过采用连续-脉冲同轴双激光焊接工艺及填充镍基合金焊丝,实现了QT500与20MnCr5的优质焊接。研究了同轴双激光中不同脉冲激光功率(360、400、440、480 W)对焊缝成形质量的影响规律,讨论了激光作用位置向钢侧偏移(偏移量)对焊接接头界面碳元素偏聚现象的影响机制,对焊接接头力学性能、金相组织及硬度分布进行了综合分析。结果表明:同轴双激光焊接工艺可用于球墨铸铁与合金钢的焊接,球墨铸铁侧的热输入对焊缝的成形质量及力学性能的影响较为显著;由于球墨铸铁侧莱氏体及马氏体的析出,断裂主要发生在该侧的熔合区;在保证熔深稳定的前提下,分别研究了不同偏移量(0.1、0.2、0.3 mm)对接头的影响,激光作用位置向钢侧偏移能够有效减小球墨铸铁侧的热输入,避免碳元素过度偏聚,力学性能得到相应的提升,断裂位置向热影响区移动,焊缝接头的强度得到优化。Objective Ductile iron has been extensively used in various automotive components such as crankshafts and differential housing owing to its relatively low density and capacity for significant tensile strength.20MnCr5 is a robust and tough alloy steel commonly employed in the production of gears and shafts.Establishing effective welding between the shaft body and the gear material is a significant research challenge.However,the notable disparity in the thermal properties between ductile iron and alloy steel hinders the performance of the welding joint.The high carbon content of ductile iron promotes carbon segregation at the welding interface and exacerbates the formation of microcracks,thereby considerably increasing the complexity of the welding process.Owing to its high energy density,laser welding offers the advantage of generating welds with more precise heat-affected zones.In this study,a novel continuous-pulse coaxial dual-beam laser is employed as a welding heat source to enhance the surface quality of the weld seam.The high-quality welding of ductile iron and alloy steel is achieved by decreasing the laser input power and diminishing pore formation.We hope that our novel welding strategy and findings will be helpful in understanding the bonding mechanism of ductile iron and alloy steel and provide more application space for their connectors.Methods In this study,QT500-7 and 20MnCr5 are employed as the base materials,with ERNiCr-3 as the filling wire.A novel continuous-pulse dual-beam laser is used as the heat source.First,the pulsed laser power is varied with a constant continuous laser power to determine the optimal combination of heat sources.The laser action position is then adjusted to further enhance the weld strength.Microstructures are observed using a metallographic microscope,and mechanical performance testing and analysis are conducted using a tensile testing machine.The microhardness of the weld is measured using a microhardness tester.Additionally,the fracture behaviors of different specimens

关 键 词：激光技术 连续-脉冲双激光 球墨铸铁 合金钢 镍基合金 

分 类 号：TG456.7[金属学及工艺—焊接]