热处理对激光选区熔化成形TC11钛合金组织性能的影响  

Effect of Heat Treatment on Microstructure and Mechanical Properties of Selective-Laser-Melted TC11 Titanium Alloys

作　　者：窦恩惠 肖美立[1] 柯林达[1] 杜磊 赖彩芳 Dou Enhui;Xiao Meili;Ke Linda;Du Lei;Lai Caifang(Shanghai Spaceflight Precision Machinery Institute,Shanghai 201600,China)

机构地区：[1]上海航天精密机械研究所,上海201600

出　　处：《中国激光》2021年第6期201-209,共9页Chinese Journal of Lasers

摘　　要：研究了退火温度和保温时间对激光选区熔化(SLM)成形TC11钛合金组织性能及断裂机制的影响。结果表明:SLM成形TC11钛合金沉积态的组织为针状马氏体,显微硬度为402 HV_(0.5),抗拉强度和断后伸长率分别为1557 MPa和2.5%,表现出高强度、低塑性的特点。经850℃/4 h和950℃/4 h退火后,组织分别为细密的α+β混合组织和α+β网篮组织,硬度和强度降低,断后伸长率升高;且断裂模式由沿晶断裂转变为韧性断裂,这与断后伸长率的变化规律一致。经950℃退火后,随退火时间缩短,α片层越细密,且晶界α相由连续分布转变为非连续分布,导致抗拉强度和断后伸长率同时增加。经950℃/1 h退火后,可获得强度和塑性匹配较佳的TC11钛合金,其抗拉强度和断后伸长率分别为1051 MPa和19.8%。Objective Selective laser melting(SLM),because of its capacity to fabricate complex precision parts with high forming accuracy,has been hailed as one of the most promising manufacturing technologies for rapid prototyping.However,the mechanical properties of metal materials formed by SLM have the characteristics of anisotropy,high strength,and low plasticity.Therefore,heat treatment is always needed to control the microstructure to meet application requirements.Annealing treatment is typically adopted to improve the mechanical properties of selectivelaser-melted titanium alloys.Therefore,study of the effect of annealing temperature and holding time on the microstructure,mechanical properties,and fracture mechanism of TC11 titanium alloys formed by SLM is of great significance.Methods The resulting microstructure,mechanical properties,and fracture morphology of selective-laser-melted TC11 titanium alloys under different heating temperature and holding time were studied,and the fracture mechanism under different conditions was explored.Firstly,compact TC11 titanium alloys were obtained by SLM.Secondly,different annealing heat treatments were performed on the samples.Thirdly,the phase composition of the different samples was analyzed by X-ray diffraction,and the microstructure morphology was observed by optical microscopy(OM)and scanning electron microscopy(SEM).Finally,the change in the micro-hardness of different samples was tested using a micro-hardness tester,the tensile properties at room temperature were tested,and the fracture morphology was observed by SEM.Results and Discussions The as-deposited TC11 titanium alloys are composed of hexagonal close-packed Ti(HCP/Ti),with lattice parametersαand c of 0.2934 nm and 0.46757 nm,respectively.The annealed samples consisted of HCP/Ti and body center cubic Ti(BCC/Ti),where a and c for HCP/Ti are 0.29172 nm and 0.46817 nm,respectively(Fig.3).Based on the observation of microstructure morphology by OM and SEM,it is deduced that the selective-laser-melted TC11 titanium

关 键 词：激光技术 激光选区熔化 TC11钛合金 热处理 组织性能 断裂机制 

分 类 号：TG166.5[金属学及工艺—热处理]