摘要
使用高功率碟片激光器在焊接功率为6.0 kW,速度为2.4 m·min^(-1),离焦量为-2 mm,保护气体为15 L·min^(-1)的参数下成功焊接6.5 mm厚的TC6钛合金板材。在此焊接参数下研究焊缝的组织演变和力学行为,结果表明焊缝内为典型的铸造态粗大β晶粒,其中心β晶内为细小交错的针状α’相,以及少量的等轴α相;熔合线处细β晶区主要为针状的α’相;近熔合线的热影响区为球化长大的α相和内部针状的α’相;近母材的热影响区仅部分片层状的α+β转变为等轴α相及内部少量α’相。从母材到热影响区到焊缝显微硬度呈上升趋势,焊缝硬度最高。拉伸结果显示焊缝的抗拉强度高于母材,延伸率略低于母材,其中静态拉伸断裂于母材,缺口拉伸断裂于焊缝,缺口敏感系数(q)为1.04。光滑拉伸试样断口内为细小均匀的韧窝,为韧性断裂;缺口拉伸试样断口内以撕裂棱为主并分布有较浅韧窝,为准解理断裂。
Titanium alloy had the advantages of high specific strength,good corrosion resistance and high temperature performance,so it was often used as a structural part in aerospace and military fields. Laser welding had the advantages of fast welding speed,small heat affected zone and no vacuum environment,and it was mainly applied to TC4 plate in titanium alloy,which mostly applied to thin plate welding. TC6 titanium alloy had higher strength and better corrosion resistance than TC4,as well as good formability. The research on welding of TC6 could provide theoretical basis and experimental basis for its application in industry. Therefore,laser welding of medium thick plate TC6 was carried out in this paper and the microstructure and properties of its joint after welding were studied. TC6 titanium alloy plate with thickness of 6.5 mm was successfully welded by high power disk laser under the parameters of welded power of 6.0 kW,welding speed of 2.4 m·min^(-1),defocusing distance of-2 mm and protective gas of 15 L·min^(-1),and the surface of the welded joint was silvery white with good formability and no obvious defects. The microstructure evolution and mechanical properties of the welded joint were studied under these welding parameters. The observation by optical microscope(OM)showed that the welded joint had a typical "I" type shape,the top and bottom surfaces were wider and the middle was narrower. The inside of the welded joint was the coarse β grain similar to the casting state,in which the fine β grain was in the fusion line of the welded joint,and the columnar β grain was in the center of the welded joint. Scanning electron microscopy(SEM)showed that the coarse β grains of the weld were mainly composed of fine and acicular structures,and a small amount of equiaxed α phases were also contained in the columnar βgrains. Through transmission electron microscope(TEM)observation and diffraction spot calibration,it could be confirmed that the fine and acicular structure inside of the welded joint was α’ phase
作者
何杨宇
杨素媛
包明明
程兴旺
He Yangyu;Yang Suyuan;Bao Mingming;Cheng Xingwang(School of Materials Science&Engineering,Beijing Institute of Technology,Beijing 100081,China;Nation・al Key Laboratory of Science and Technology on Materials under Shock and Impact,Beijing 100081,China)
出处
《稀有金属》
EI
CAS
CSCD
北大核心
2021年第8期914-920,共7页
Chinese Journal of Rare Metals
基金
国家自然科学基金项目(51571031)资助。
关键词
钛合金
激光焊
显微组织
力学性能
titanium alloy
laser beam welding
microstructure
mechanical property
