焊丝成分对国产Invar合金GTAW接头组织差异性的影响  

Effect of Welding Wire Composition on Microstructure Inhomogeneity of Domestic Invar Alloy GTAW Joint

作　　者：程立宏 周裕琦 王建峰 李柱 穆战 占小红[1] CHENG Lihong;ZHOU Yuqi;WANG Jianfeng;LI Zhu;MU Zhan;ZHAN Xiaohong(College of Materials Science and Technology,Nanjing University of Aeronautics and Astronautics,Nanjing 211106,China;Xi’an Gangyan Special Alloy Co.,Ltd.,Xi’an 710000,China)

机构地区：[1]南京航空航天大学材料科学与技术学院,南京211106 [2]西安钢研功能材料股份有限公司,西安710000

出　　处：《材料导报》2024年第23期145-150,共6页Materials Reports

基　　金：中央高校基本科研业务费专项资金(NF2022003)。

摘　　要：采用钨极惰性气体保护焊(Gas tungsten arc welding,GTAW)工艺完成15 mm厚国产Invar合金的焊接,研究了焊丝成分对接头组织差异性的影响。结果表明:三种焊丝所获得的显微组织均由焊缝边缘垂直于熔合线生长的粗大柱状晶和焊缝中部的等轴晶组成,等轴晶内部的亚晶结构明显细化。使用不同成分焊丝后在焊缝形成的析出相种类、形态与分布位置存在较大差别。采用添加0.40%Ti的焊丝在晶界析出较多规则的块状颗粒,而添加1.42%Nb的焊丝在亚晶界析出白色链状或柱状连续相。析出相不仅能作为异质形核的核心或钉扎晶界的质点细化晶粒,还可以作为沉淀相阻碍位错运动从而提高焊缝强度。试样拉伸结果表明:焊丝加入0.40%Ti、1.42%Nb后,接头的抗拉强度大幅提升,分别达到638.2 MPa和653.5 MPa,相较原始焊丝分别提高60.6%、64.4%。断口形貌表明采用含铌焊丝(1.42%Nb)后断口韧窝尺寸和深度增大,接头断裂模式由脆性断裂转变为韧性断裂,说明Nb元素对Invar合金接头组织细化、力学性能改善具有显著作用。The influence of wire composition on the microstructure varieties of joints was studied by using gas tungsten arc welding(GTAW)process.Results showed that the microstructure of welded joint obtained by using the three welding wires are featured coarse columnar crystals grown perpendicular to the fusion lines and equiaxed crystals in the middle of weld,cellular subcrystals in equiaxed crystals are remarkably refined.There was a large differences in the type,morphology and distribution position of precipitated phases formed when using welding wires of different composition.When using the welding wire with 0.40%Ti,more regular bulk particles were precipitated at the grain boundary,and if useing the welding wire with 1.42%Nb,a white chain or columnar continuous phase were precipitated at the subgrain boundary,which not only enabled the core of heterogeneous nucleation or the particle that nails the grain boundary to refine the grain,but also hindered dislocation motion to strengthen the welded joint.The tensile test results showed that the tensile strength of the joints with 0.40%Ti addtion or 1.42%Nb addtion to the welding wire reached 638.2MPa or 653.5 MPa respectively,which are 60.6%and 64.4%higher than that of conventional welding wire.When the specimen was welded with the welding wire that with Nb(1.42%Nb)addition,the size depth of the fracture ligament increased,and the joint fracture mode changed from brittle fracture to ductile fracture,indicating that Nb plays a significant role in the microstructure refinement and mechanical properties improvement of Invar alloy joints.

关 键 词：国产Invar合金 焊丝成分 显微组织 力学性能 断口形貌 

分 类 号：TG422.3[金属学及工艺—焊接]