热处理对LMD TC4组织、力学性能及各向异性的影响  

Effects of Heat Treatment on Microstructure,Mechanical Properties,and Anisotropy of Laser Melting Deposited TC4

作　　者：王普强 王豫跃[1] 吴梦杰 窦振 张安峰[2] Wang Puqiang;Wang Yuyue;Wu Mengjie;Dou Zhen;Zhang Anfeng(State Key Laboratory for Mechanical Behavior of Materials,Xi'an Jiaotong University,Xi'an,Shaanxi 710049,China;State Key Laboratory for Manufacturing Systems Engineering,Xi'an Jiaotong University,Xi'an,Shaanxi 710054,China)

机构地区：[1]西安交通大学金属材料强度国家重点实验室,陕西西安710049 [2]西安交通大学机械制造系统工程国家重点实验室,陕西西安710054

出　　处：《中国激光》2021年第10期154-165,共12页Chinese Journal of Lasers

基　　金：国家重点研发计划(2016YFB1100102);国家自然科学基金(51775417)。

摘　　要：采用光学显微镜、扫描电子显微镜、能谱仪、X射线衍射仪、拉伸试验机研究了热处理工艺对激光熔化沉积(LMD)TC4合金微观组织、力学性能及各向异性的影响。结果表明:由于激光能量密度较大,沉积态合金的微观组织为细小的α+β片层及晶界处的魏氏α集束组织,晶界连续,强度最高,塑性与硬度最低,塑性的各向异性最大;在单重固溶时效体系中,随着固溶温度升高,初生α板条不断粗化,晶界断裂程度加剧,硬度不断增加;固溶时效+退火后初生α相的含量最高,塑性最高,但强度最低,硬度居中;在双重固溶时效体系中,随着第二重固溶温度升高,初生α板条进一步粗化,晶界断裂程度加剧,硬度呈下降趋势。经980℃/1 h/空冷+550℃/4 h/空冷+980℃/1 h/空冷+550℃/4 h/空冷处理后,晶界基本全部断裂,硬度较低,强塑性匹配较好,塑性的各向异性最小。Objective Ti-6Al-4V(TC4)titanium alloy has excellent corrosion resistance,and high specific strength and yield ratio.It is widely used in the aerospace,navigation,and biomedical industries.For structural parts with complex shapes,traditional processing techniques are complicated,resulting in low material utilization and high manufacturing costs.Laser melting deposited(LMD)TC4 alloy components have the advantages of low cost,short cycle,and high performance.TC4 titanium alloy is a dual-phase alloy,consisting of two phases:β-phase stable at high-temperature and α-phase stable at room temperature.The microstructure types consist of Widmanstatten,basket,dual-state,and equiaxed structures.Different microstructure morphology,size,phase ratio,and distribution have a significant impact on the performance of this alloy.Due to the principle of layer by layer in the laser additive manufacturing process,the temperature gradient in the deposition direction is very high,leading to the columnar grains growing along the deposition direction and continuous α-phase at the columnar grain boundaries,thereby resulting in large anisotropy of mechanical properties,especially plastic anisotropy.The structural optimization of LMD TC4 alloy through a reasonable heat treatment process can effectively improve the mechanical properties of this alloy and reduce anisotropy.Some researchers found that the matching of this alloy's strength and plasticity is best after solution-aging treatment.Thus,this study focuses on the effects of the solution-aging heat treatment process on the microstructure,mechanical properties,and anisotropy of the LMD TC4.Methods In this study,TC4 titanium alloy powder with a particle size of 50--150μm is used.TC4 titanium alloy block is formed by a laser additive manufacturing system.The powder is dried in a vacuum drying oven.The formation process is conducted under the protection of argon gas,and the laser scanning path is a vertical cross-reciprocating form.Use wire cutting to cut the tensile specimens in the mi

关 键 词：激光技术 激光熔化沉积 TC4合金 热处理 微观组织 力学性能 各向异性 

分 类 号：TG146.23[一般工业技术—材料科学与工程] TG166.5[金属学及工艺—金属材料]