TC4钛合金MIG焊接头热处理后组织性能研究  

Research on microstructure and properties of TC4 titanium alloy MIG welded joints after heat treatment

作　　者：何逸凡 陈东高[1] 张龙 王大锋 邵志文[1] 马良超 He Yifan;Chen Donggao;Zhang Long;Wang Dafeng;Shao Zhiwen;Ma Liangchao(Ningbo Branch of Chinese Academy of Ordnance Science,Ningbo 315103,Zhejiang,China)

机构地区：[1]中国兵器科学研究院宁波分院,浙江宁波315103

出　　处：《钢铁钒钛》2021年第6期164-170,共7页Iron Steel Vanadium Titanium

摘　　要：对TC4钛合金MIG焊焊接接头进行焊后热处理,采用盲孔法、拉伸、冲击、金相、扫描等方法对接头进行试验与分析,研究不同热处理工艺对残余应力、组织和力学性能的影响。结果表明:焊接接头经焊后热处理,横向残余应力和纵向残余应力平均值最大降为74.2 MPa和70.1 MPa;未热处理接头母材区为α+β片层组织,焊缝区为α'针状马氏体组织,热影响区为α和α'混合组织。热处理后,随着热处理温度和时间的增加,焊缝组织中的针状α'马氏体粗化,晶粒尺寸增加;未热处理接头焊后拉伸断裂位置为母材处,接头强度高于母材。在650℃+2 h的热处理工艺下,接头延伸率较未热处理状态提高,断裂方式为韧性断裂,保温时间延长至3 h,晶粒粗大、延伸率降低。接头室温冲击功焊后状态能够达到母材的95%,经焊后热处理后接头得到软化,室温冲击功相比焊后状态有所下降。Post heat treatment processes had been carried out on TC4 titanium alloy MIG welded joints.The effects of different heat treatment processes on residual stress,microstructure and mechanical properties on resulting TC4 titanium alloy MIG welded joints had been investigated through the blind-hole method,mechanical test and microstructure observation.The results show that average transverse residual stress and longitudinal residual stress of the welded joint after post heat treatment are reduced down to 74.2 MPa and 70.1 MPa,respectively.The base material isα+βlamellar structure,and the weld joint isα'needle shape martensite structure,the heat-affected zone is a mixed structure ofαandα'.After heat treatment,with increasing heat treatment temperature and prolonging time,the acicularα'martensite in the weld structure becomes coarser,and grain size increases.For unheated-treatment joint,tensile fracture position locates at base metal,indicating higher joint strength compared with the base material.When the weld joint is subjected to a heat treatment process of 650℃+2 h,the elongation of the joint is higher than that in the unheated state,and the fracture mode is a ductile fracture.When the holding time is extended to 3 h,the grain becomes coarse,and the elongation decreases.The impact energy of the welding joint after post heat treatment at room temperature can reach 95%of that of base metal.The post-weld heat treatment can soften the welding joint,resulting in lower room temperature impact energy than the as-welding joint.

关 键 词：TC4钛合金 MIG焊 焊后热处理 力学性能 显微组织 

分 类 号：TF823[冶金工程—有色金属冶金] TG456[金属学及工艺—焊接]