固溶过程中冷却速率对Ti-6Al-4V-0.5Fe合金组织和力学性能的影响

Effects of Cooling Rate in Solution Process on Microstructure and Mechanical Properties of Ti-6Al-4V-0.5Fe Alloy

对Ti-6Al-4V-0.5Fe热轧合金依次进行860℃退火处理和950℃固溶处理试验,并且在固溶处理过程中采用不同的冷却速率,之后使用光学显微镜观察不同热处理状态的微观组织形貌,测试合金的拉伸性能和显微硬度,并采用激光共聚焦显微镜观察硬度压痕的三维形貌。结果表明,退火处理未能明显改变合金的组织形貌,但降低了合金的显微硬度,减少了合金在轧制过程中的加工硬化程度。合金经950℃固溶处理(水冷)后,存在等轴组织,由等轴α相和晶间β相组成,且组织均匀细小,合金可获得较高的显微硬度。固溶处理能够调控合金的组织,为进一步通过时效处理提高该合金的力学性能提供条件。

Ti-6 Al-4 V-0.5 Fe hot-rolled alloy was annealed at 860 ℃ and solid solution treated at 950 ℃. In the process of solution treatment, different cooling rates were used, and then the microstructure of the alloy in different heat treatment states was observed by optical microscope.The tensile properties and microhardness of the alloy were tested. The three-dimensional morphology of hardness indentation was observed by laser confocal microscope. The results show that, the annealing treatment can not obviously change the microstructure of the alloy, but the microhardness of the alloy is reduced. The work hardening degree of the alloy in rolling process is reduced. After solid solution treatment at 950 ℃(water cooling), the alloy has equiaxed structure, it is composed of equiaxed α phase and intergranular β phase, and the microstructure is uniform and fine, the alloy can obtain higher micro-hardness. The microstructure of the alloy can be regulated by solution treatment, which provides conditions for further improving the mechanical properties of the alloy by aging treatment.