论文部分内容阅读
通过高温拉伸试验研究了Ti-6Al-4V合金的高温变形力学行为和超塑性,并对试样断口附近的组织进行了观察。结果表明,随着变形温度的升高或初始应变速率的降低,Ti-6Al-4V合金的流动应力明显减小;Ti-6Al-4V合金的最佳超塑性变形工艺参数为880℃/0.001s-1,最大延伸率为689%,峰值应力仅为30.03MPa;在超塑性拉伸过程中,试样变形区发生明显的动态再结晶,使片层状的α相晶粒破碎、细化和等轴化,促进超塑性的增加;随着变形温度的提高、变形量增大和变形时间的加长,再结晶α相发生了聚集长大,从而使显微组织明显粗化。对于双态组织的两相钛合金,最佳超塑性变形温度应低于或等于片层状α→β转变的终了温度。
The high-temperature deformation mechanical behavior and superplasticity of Ti-6Al-4V alloy were studied by high-temperature tensile test. The microstructure of Ti-6Al-4V alloy was observed. The results show that the flow stress of Ti-6Al-4V alloy decreases with the increase of the deformation temperature or the initial strain rate. The optimum superplastic deformation parameters of Ti-6Al-4V alloy are 880 ℃ / 0.001s -1, the maximum elongation is 689% and the peak stress is only 30.03MPa. During the process of superplastic stretching, the dynamic recrystallization of the specimen takes place obviously, which makes the lamellar α-phase grains broken, refined and Equiaxed, and promote the increase of superplasticity. With the increase of deformation temperature, deformation and lengthening of deformation time, the recrystallizedαphase aggregates and grows, so that the microstructure is obviously roughened. For a dual-phase, two-phase titanium alloy, the optimum superplastic deformation temperature should be less than or equal to the end temperature of lamellar α → β transformation.