固溶处理对TC11钛合金组织与性能的影响

Effect of solution treatment on microstructure and properties of TC11 titanium alloy

通过光学显微镜、扫描电镜、X射线衍射仪以及室温拉伸性能测试,研究TC11钛合金分别在955、975、995和1015℃固溶处理后的微观组织与力学性能的对应关系。结果表明,合金原始锻态显微组织为α+β两相区锻造形成的双态组织,以α_(p)相和β转变组织为主。经固溶处理后,原始锻态组织中被扭转和拉长的α_(p)相随着固溶温度升高逐渐变小、变圆,同时体积较小的α_(p)相逐渐消失。固溶温度为995℃时,合金强度达到最大值,抗拉强度(R_(m))为1403 MPa,屈服强度(Rp_(0.2))为1158 MPa;固溶温度为955℃时,合金塑性最佳,断后伸长率(A)为9.5%,断面收缩率(Z)为32%。当固溶温度位于两相区时,其拉伸断口微观形貌相似,均以韧窝为主;当固溶温度位于单相区时,断口形貌结晶状明显,且有较大的撕裂棱,在岩石状表面有大量撕裂状小韧窝。

Relationship between microstructure and mechanical properties of the TC11 titanium alloy after solution treatment at 955, 975, 995 and 1015 ℃, respectively, was studied by means of optical microscope, scanning electron microscope, X-ray diffraction and room temperature tensile test. The results show that the original as-forged microstructure of the alloy is a bimodal structure formed by forging in the α+β two-phase region, which is dominated by αpphase and β transformation structure. After solution treatment, the twisted and elongated αpphase in the original as-forged structure gradually becomes smaller and rounded with the increase of solution treatment temperature, and the smaller αpphase gradually disappears. When the solution treatment temperature is 995 ℃, the strengths of the alloy reach the maximum, of which the tensile strength(R_(m)) is 1403 MPa and the yield strength(R_(p0.2)) is 1158 MPa. When the solution treatment temperature is 955 ℃, the plasticity of the alloy is the best, of which the elongation after fracture(A) is 9.5% and the percentage reduction of area(Z) is 32%. When the solution treatment temperature is in the two-phase region, the tensile fracture morphology is similar, which is mainly dimples. When the solution treatment temperature is in the single-phase region, the fracture morphology is obviously crystalline and has large tearing edges, and there are a large number of small tearing dimples on the rock-like surface.