热处理对同质异态TC17钛合金线性摩擦焊接头的影响  

Effect of Heat Treatment on Linear Friction Welding Joints of TC17 Titanium Alloys with Dissimilar Microstructures

作　　者：常川川 李菊 李晓红 金俊龙 张传臣 季亚娟 CHANG Chuanchuan;LI Ju;LI Xiaohong;JIN Junlong;ZHANG Chuanchen;JI Yajuan(Aeronautical Key Laboratory for Welding and Joining Technologies,AVIC Manufacturing Technology Institute,Beijing 100024,China;Beijing Friction Welding Technology and Equipment Engineering Center,Beijing 100024,China)

机构地区：[1]中国航空制造技术研究院航空焊接/连接技术航空科技重点实验室,北京100024 [2]北京市摩擦焊接工艺与装备工程中心,北京100024

出　　处：《材料导报》2024年第8期181-185,共5页Materials Reports

基　　金：国家自然科学基金(52105411);国家科技重大专项(2017-Ⅶ-0005-0098)。

摘　　要：对TC17(α+β)和TC17(β)钛合金进行线性摩擦焊及焊后热处理试验,运用光学显微镜(OM)、扫描电镜(SEM)观察接头各区域的微观组织变化,采用轮廓法测试接头残余应力分布情况,分析了热处理对接头的微观组织、残余应力及力学性能的影响。结果表明:焊接过程中焊缝区发生了相变及动态再晶界过程,形成亚稳定β相;两侧热力影响区初生α相严重变形,针状α相完全溶解。经过热处理,亚稳定β相分解为稳定的α+β相,板条状α相在晶界析出,针状α相在晶粒内部析出,变形α相发生不同程度的分解。轮廓法测试结果表明,接头沿振动方向的应力呈双峰分布,接头热力影响区处拉应力峰值达到最大约360 MPa,焊缝中心拉应力值约140 MPa,经过热处理,接头沿振动方向拉应力值降低至50 MPa以下。经过热处理后接头微观组织更加均匀,并且接头残余应力得到消除,接头拉伸及疲劳性能得到明显改善。This work presented the influences of the heat treatment on the microstructure, residual stress and mechanical properties of the linear friction welding joint through carrying out linear friction welding (LFW) and post-weld heat treatment (PWHT) tests on TC17 (α+β) and TC17 (β) titanium alloys, observing and analyzing the microstructure changes of the joint by optical microscope (OM) as well as scanning electron microscope (SEM) and testing the residual stress distribution of the joint by the contour method. The results showed that phase transition and dynamic recrystallization process occurred during the welding process, and the metastable β phase was formed in weld zone. The primary α phase of the thermo-mechanically affected zone (TMAZ) on both sides was severely deformed, and the needle-like α phase was completely dissolved. After PWHT, the metastable β phase was decomposed into stable α+β phase, the lath α phase precipitating at the grain boundary and needle-like α phase within the grains could be found, and the deformed α phase was decomposed. The residual stress of the joint tested by contour method has a bimodal distribution along the vibration direction. The peak tensile stress located on the TMAZ of the joint reached about 360 MPa, and the tensile stress value at the weld center reduced to 140 MPa. The residual stress value of the joint was reduced to less than 50 MPa after PWHT. When the process of PWHT was finished, the microstructure of the joint was more uniform, and the residual stress of the joint was eliminated, so that the tensile and fatigue properties of the joint were significantly improved.

关 键 词：TC17钛合金 线性摩擦焊 残余应力 焊后热处理 力学性能 

分 类 号：TG453[金属学及工艺—焊接]