Inconel 690局部干法水下激光焊接接头组织及性能研究  

Study on Microstructure and Properties of Inconel 690 Local Dry Underwater Laser Welded Joints

作　　者：朱兆剑 韩柯 李洪亮 朱强[1] Zhu Zhaojian;Han Ke;Li Hongliang;Zhu Qiang(School of Materials Science and Engineering,Jiangsu University,Zhenjiang 212000,Jiangsu,China)

机构地区：[1]江苏大学材料科学与工程学院,江苏镇江212000

出　　处：《中国激光》2023年第16期59-70,共12页Chinese Journal of Lasers

摘　　要：采用气体辅助排水装置对Inconel 690合金进行水下局部干法激光焊接,研究了热输入和离焦量对焊缝成形、横截面几何特征、对接接头缺陷和力学性能的影响,从而实现工艺参数优化。结果表明:热输入对焊缝的宽度影响较大,熔池的Marangoni流动和金属蒸气的喷发导致顶部区域宽度扩大。焊缝的结晶形态由平面状经过胞状转变为树枝状。随着焊接热输入的减小,焊缝晶粒尺寸减小,力学性能则不断增强。焊缝的宽度随离焦量的增加而改变,离焦量为零时,接头力学性能最佳。水下和陆上焊接获得的接头显微组织均由胞状晶、柱状晶和树枝晶组成。陆上焊接接头枝晶间存在Cr和Ni元素偏析现象。而水下焊接过程中水的快速冷却作用有助于改善接头枝晶间的合金偏析程度,但恶化了合金元素晶内偏析。在最佳焊接工艺参数下,水下焊接接头的抗拉强度和陆上焊接接头相似,冲击韧性亦达到陆上焊接接头的90%,显微硬度则高于陆上焊接接头。Objective The Inconel 690 alloy has been widely used to manufacture nuclear steam generator tubes of pressurized water reactors and components of boiling water reactors owing to its excellent performance.However,corrosion and wear lead to local component damage during long-term operation under a high-temperature environment.Underwater repair can significantly reduce the amount of radiation exposed during the maintenance work.Compared with traditional underwater arc welding,underwater laser welding has the advantages of high control accuracy,wide range of welding materials,accurate control of heat input,a small heat-affected zone,and low residual stress.However,laser welding conducted directly under water aggravates the problem of porosity.Therefore,in this study,a gas drainage hood is used to drain the water around both sides of a welding sample,in order to provide protection during the underwater local dry laser welding of the Inconel 690 alloy.Methods The underwater local dry laser welding of the Inconel 690 alloy with the gas-assisted drainage device is carried out.During the laser welding process,the entire gas-assisted drainage cover is fixed under the welding head by a self-designed fixture.When argon flows from the nozzle,water is discharged and a local dry chamber is formed.Argon simultaneously serves as a shielding gas.The back protection system of a clamp fills with argon and discharges water from the area to be welded,wherein argon provides protection during the laser welding process.The effects of heat input and defocusing amount on weld formation,welding defect generation,and mechanical properties of the Inconel 690 alloy joint are studied by a single factor control method.Moreover,the process parameters of underwater local dry laser welding are optimized.Finally,the feasibility of underwater welding is proven by comparing the microstructures and welding properties of the underwater and onshore welded joints prepared under the same process parameters.Results and Discussions As the heat input increase

关 键 词：激光技术 水下激光焊接 Inconel 690合金 焊缝外观 显微组织 力学性能 

分 类 号：TG456.7[金属学及工艺—焊接]