退火工艺对增材制造TC18钛合金力学性能和组织的影响

采用显微组织观察和力学性能测试等方法研究了退火工艺参数对增材制造TC18钛合金力学性能和组织的影响。结果表明,增材制造TC18钛合金试块宏观形貌平整,表面没有裂纹等缺陷,表面呈均匀的银白色。试样经600 ℃退火保温2 h后的各项力学性能均满足GJB 2744A—2007指标要求,其规定塑性延伸强度为1036 MPa,抗拉强度为1084 MPa,断后伸长率为9.8%,断面收缩率为30%。增材制造TC18钛合金的组织为典型的柱状晶组织,粗大的β相柱状晶粒内为细长的针状α相及编织细密的α+β相板条组织;随着退火温度的升高,β相柱状晶内的针状α相逐渐粗化。

Effect of annealing process on mechanical properties and microstructure of additive manufactured TC18 titanium alloy

Effect of annealing parameters on mechanical properties and microstructure of TC18 titanium alloy was studied by means of microstructure observation and mechanical properties test. The results show that the tested block of TC18 titanium alloy made by additive manufacturing has no cracks observed, and possesses flat, smooth and uniformly silver-white surface. The mechanical properties of specimens annealed at 600 ℃ for 2 h are both satisfied with standard requirement of the GJB 2744A—2007, and its R_p0.2, R_m, A and Z are 1036 MPa, 1084 MPa, 9.8% and 30%, respectively. The microstructure of TC18 titanium alloy made by additive manufacturing is the typical structure of columnar crystal, and in the coarse columnar grains of β phase, there is elongated needle-like α phase and fine woven α+β lath structure. With the increase of annealing temperature, the needle-like α phase in the columnar grain is coarsened gradually.