摘要
采用电子束熔丝增材工艺制造了直径260 mm的试环。分析了不同热处理状态的增材制造TC11钛合金微观组织和室/高温拉伸性能及其各向异性。并测试分析了锻件基体晶粒2次热处理和锻件基体与增材界面处的组织和性能。结果表明:沉积态微观组织为沿<001>β方向生长的柱状晶。晶界存在连续α相,晶体内部由集束和网篮α相组成的片层组织。经950℃/2h/空冷+530℃/6h/空冷的热处理后晶界连续α相破碎,晶内α相宽度从1.1μm增加至1.8μm。并形成具有二次α相的双片层组织。锻件与增材过渡区锻件一侧,等轴初生α相转变为“雪花”状初生α相。锻件基体2次热处理后等轴初生α相轮廓光滑,转变β相比例增加,并形成大量细小的针状二次α相。沉积态室温及500℃高温拉伸性能均具有明显的各向异性。经过热处理后室/高温拉伸性能均获得改善并高于锻件要求且各向异性明显降低。与沉积态相比,热处理态室温抗拉强度和断后伸长率各向异性分别从4.4%和27.1%降低至1.6%和5.4%。柱状晶及其晶界连续α相是引起塑性各向异性的原因。锻件+增材界面处热处理后其室/高温拉伸性能均满足锻件要求。
In this study,aα+βhigh-temperature titanium alloy TC11 ring(φ260 mm)was fabricated by wire-feed electron beam additive manufacturing(EBAM).The microstructure,tensile property and the anisotropy of the tensile properties of the fabricated alloy were investigated.The microstructure and tensile property of the wrought alloy and the wrought+additive manufacturing interface were also evaluated.Optical microscopy,scanning electron microscopy,transmission electron microscopy and X-ray diffraction were employed to study the microstructure characteristics.The tensile properties along the vertical(V)and horizontal(H)directions were evaluated at both room temperature and 500℃.Results indicated that the microstructure of the as-built alloy was characterized by coarse columnar grains,lamellarα(colony and basket-weave),and the continuous grain boundaryα.The priorβgrains had a strong<001>βtexture along the grain growth direction.Compared to the as-built alloy,the lamellarαphase was coarsened from 1.1μm to 1.8μm,the discontinuous grain boundaryαand bi-lamellarαphase formed by post-deposition heat treated at 950℃/2 h/AC+530℃/6 h/AC.The equiaxed primaryαof the wrought substrate alloy changed from globular to snowflake near the interface.After heat treatment,the volume fraction of the transformedβdecreased for the wrought substrate alloy.In terms of tensile properties,the vertical specimens exhibited lower strength but higher ductility than the horizontal specimens at both room and elevated temperatures.The anisotropic elongation results from the directional columnar priorβgrains and continuous grain boundaryαphase,which facilitated the intergranular cracking.The tensile strength and ductility were simultaneously enhanced by the heat treatment to meet the standard requirements for wrought counterparts.Moreover,the anisotropy of the tensile strength and elongation for the post-deposition heat treated alloy was decreased significantly from 4.4%and 27.1%to 1.6%and 5.4%,respectively,in comparison to the as-built alloy.The tensile property of the wrought+additive manufacturing interface can meet the standard requirements for wrought counterparts.
作者
张国栋
张鹏
高健时
余槐
袁鸿
丁宁
熊华平
ZHANG Guodong;ZHANG Peng;GAO Jianshi;YU Huai;YUAN Hong;DING Ning;XIONG Huaping(3D Printing Research and Engineering Technology Center,AECC Beijing Institute of Aeronautical Materials,Beijing 100095;The Sixth Military Representative Office of Airforce in Beijing,Beijing 100024)
出处
《机械工程学报》
EI
CAS
CSCD
北大核心
2023年第4期105-112,共8页
Journal of Mechanical Engineering
关键词
钛合金
电子束
增材制造
组织
力学性能
各向异性
titanium alloy
electron beam
additive manufacturing
microstructure
mechanical property
anisotropy
