摘要
对TC17(α+β)/TC17(β)钛合金线性摩擦焊接头进行热处理实验,采用光学显微镜(OM),扫描电子显微镜(SEM)和显微硬度仪等检测手段,研究不同热处理温度对焊接接头微观组织及力学性能的影响。结果表明:焊态下,接头焊缝区发生再结晶,界面处为亚稳定β相组织,显微硬度低于母材,接头高周疲劳强度为345 MPa。TC17(α+β)侧热力影响区因焊接速率过快,残留了大量的初生α相。经过焊后热处理,亚稳定β相分解,焊缝析出弥散的(α+β)相。随着热处理温度的升高,细小的次生α相长大,部分发生球化。热处理后,因亚稳定β相分解,焊缝及热力影响区的显微硬度大幅度升高,接头疲劳强度平均提高65 MPa;随着热处理温度的升高,接头热力影响区的断裂韧度增加。
The heat treatment experiments were carried on titanium alloys(TC17(α+β)+TC17(β))linear friction welded joint.Optical microscope(OM),scanning electron microscope(SEM)and microhardness instrument were used to investigate the effects of different heat treatment temperatures on the microstructure and mechanical properties of welded joints.The results show that recrystallization occurs at the weld zone(as weld).Metastableβphase structure is formed at the weld interface of as-welded joint.The microhardness of as-welded joint is lower than base metal and high cycle fatigue strength of as-welded joints is 345 MPa.Because welding speed is rapid,a large number of primaryαphase is retained in thermal mechanically affected zone(TMAZ)of TC17(α+β).After post-weld heat treatment,the metastableβphase structure is decomposed and dispersed(α+β)phase is separated out at the welded joints.With the increase of the heat treatment temperature,small secondaryαphase is grown up and phases are partly spheroidized.After heat treatment,because metastableβphase structure is decomposed,the micro-hardness is greatly increased at the weld zone and TMAZ,and fatigue strength is increased by an average of 65 MPa at the welded joints.With the increase of the heat treatment temperature,the fracture toughness is improved at the TMAZ of welded joints.
作者
李晓红
张彦华
李赞
李菊
张田仓
LI Xiao-hong;ZHANG Yan-hua;LI Zan;LI Ju;ZHANG Tian-cang(School of Mechanical Engineering&Automation,Beihang University,Beijing 100191,China;Aeronautical Key Laboratory for Welding and Joining Technologies,AVIC Manufacturing Technology Institute,Beijing 100024,China)
出处
《材料工程》
EI
CAS
CSCD
北大核心
2020年第1期115-120,共6页
Journal of Materials Engineering
基金
国家科技重大专项资助(2017-Ⅶ-0005-0098)
关键词
TC17钛合金
线性摩擦焊
热处理
力学性能
TC17 alloy
linear friction welding
heat treatment
mechanical property
