TC4合金高温拉伸变形力学行为与微观组织演变关联研究

发布时间：2019-04-01 17:14

【摘要】：基于TC4合金高温恒应变速率拉伸试验和微观组织观察,研究了工艺参数对TC4合金流动应力、应变速率敏感性指数、应变硬化指数和微观组织演变的影响规律,获得了TC4合金高温拉伸变形时宏观力学行为与微观组织演变的关联机制。结果表明:当变形温度为1123~1213 K、应变速率为0.1 s-1时,TC4合金的拉伸应变不超过0.7就会出现局部颈缩并导致开裂;当应变速率为0.01 s-1、变形温度为1183 K时,TC4合金的应变速率敏感性指数m值最大,归因于该变形条件下初生α相呈等轴状且较细小;当应变速率为0.01 s-1时,随着应变增加,应变硬化指数n值呈逐渐减小的趋势,归因于加工硬化和动态软化的共同作用;随着变形温度升高,初生α相由长条状转变为等轴状,随着应变速率增加,初生α相呈现出明显的取向性,不利于晶界滑动或旋转;应变对初始α相形貌和含量影响较小,但对次生α相影响显著。
[Abstract]:Based on the high temperature constant strain rate tensile test and microstructure observation of TC4 alloy, the effects of process parameters on flow stress, strain rate sensitivity index, strain hardening index and microstructure evolution of TC4 alloy were studied. The correlation mechanism between macroscopic mechanical behavior and microstructure evolution of TC4 alloy during tensile deformation at high temperature was obtained. The results show that when the deformation temperature is 1123 ~ 1213 K and the strain rate is 0.1 s ~ (- 1), the local necking and cracking will occur when the tensile strain of TC4 alloy is less than 0.7. When the strain rate is 0.01 s / 1 and the deformation temperature is 1183 K, the strain rate sensitivity index m of TC4 alloy is the largest, which is attributed to the equiaxed and fine initial 伪 phase under this deformation condition. When the strain rate is 0.01 s ~ (- 1), the strain hardening exponent n decreases gradually with the increase of strain, which is attributed to the combination of work hardening and dynamic softening. With the increase of deformation temperature, the primary 伪 phase changes from strip to equiaxed. With the increase of strain rate, the primary 伪 phase shows obvious orientation, which is not conducive to grain boundary sliding or rotation. The strain has little effect on the morphology and content of the initial 伪 phase, but has a significant effect on the secondary 伪 phase.
【作者单位】：中航工业第一飞机设计研究院;
【分类号】：TG146.23

【参考文献】