热变形TA15钛合金的显微组织和室温力学性能

Microstructure and Mechanical Properties of Hot Deformed TA15 Titanium Alloy at Room Temperature

通过等温恒应变速率压缩实验和X射线衍射、电子背散射衍射和透射电镜,研究了β区加热后在不同的变形温度和变形速率下变形水冷后TA15钛合金的微观组织;通过室温拉伸试验,对其抗拉强度和延伸率等性能进行了测试。结果表明,在α+β两相区压缩变形时,β转变组织中α相产生球化;水冷后发生β→α'马氏体相变。合金由球化α相、片状次生α相和针状马氏体α'相组成。在β相区压缩变形水冷后,合金主要为针状马氏体α'相。在相变点之上或之下的温度区间,随着变形温度的升高,合金的抗拉强度降低,延伸率增加;在相变点附近的温度过渡区间,随着变形温度的升高,合金的抗拉强度略有升高,延伸率降低。在相变点附近的两相区变形能获得较好的室温强塑性匹配。

Near α TA15 titanium alloy with initial equiaxed microstructure was β heated and then water quenched. Afterwards, the microstructure evolution of the samples during isothermal compression at different deformation temperatures and strain rates was investigated using X-ray diffraction（XRD）, electron backscatter diffraction（EBSD） and transmission electron microscopy（TEM） analysis. The tensile strength and elongation were measured by conducting micro-tensile tests. The results show that α phase globularization occurs when the alloy is deformed in α＋β temperature range. High temperature β phase transforms into martensite α＇ after water cooling. The alloy is composed of equiaxed α, lamellar secondary α and acicular martensite α＇. When the alloy is compressed in β temperature range, the microstructure is basically acicular martensite α＇ phase. In the temperature ranges below or above phase transformation point, with the increasing of temperature, the tensile strength decreases and the elongation increases. But in the temperature range around phase transformation point, with the increasing of temperature, the tensile strength increases slightly and the elongation decreases. In the two-phase region near phase transition point, better strength and plasticity can be obtained.