真空退火对TA15合金板材组织和力学性能的影响

摘要

研究TA15板材在不同条件下真空退火后的力学性能、显微组织和断口形貌。结果表明：相比非真空退火，真空退火显著提高板材的力学性能。随着退火温度的升高，相界面和次生α相增多，但初生α相体积分数减少，从而导致板材的强度提高，伸长率降低。双重退火后获得的次生α相更加细小。在(950°C/2 h, AC)+(600°C/2 h, AC)下双重退火获得了良好的力学性能，其抗拉强度、屈服强度和延伸率分别为1070 MPa,958 MPa和15%。从拉伸断口形貌可以看到，最深最大的韧窝出现在850°C退火试样上，说明在该温度下退火板材塑性最好。%The mechanical properties, microstructures, and fractographs of TA15 sheets vacuum-annealed under different patterns were investigated. The results indicate that vacuum annealing significantly improves the mechanical properties of the sheets in comparison with those after ambient annealing. With increasing the annealing temperature, the phase boundaries and secondaryα-phase increase, whereas the volume fraction of primaryα-phase decreases, resulting in increased strength and decreased elongation. A relatively fine secondaryα-phase is obtained after double annealing. The desirable mechanical properties (i.e., ultimate tensile strength, yield strength, and elongation are 1070 MPa, 958 MPa, and 15%, respectively) are obtained through double annealing ((950 °C/2 h, AC)+(600 °C/2 h, AC)). The fractographs obtained after tensile tests show that the deepest and largest dimples are formed in the specimen annealed at 850 °C, which indicates that the best plasticity is obtained at this annealing temperature.