锻压技术

TC4合金高温拉伸变形力学行为与微观组织演变关联研究

英文标题：Study on the correlation of flow behavior and microstructure evolution during the high temperature tensile deformation of TC4 alloy

作者：李波张沛

单位：中航工业第一飞机设计研究院

关键词：TC4合金流动应力应变速率敏感性指数应变硬化指数微观组织演变

分类号：TG319

出版年,卷(期):页码：2015,40(6):108-115

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。

The influences of processing parameters on flow stress, strain rate sensitivity exponent, strain hardening exponent and microstructure evolution were investigated based on high temperature tensile test under the constant strain rate and microstructure examination of titanium alloy TC4, and the correlation of flow behavior and microstructure evolution was obtained. The results show that the local necking will appear and lead to crack at deformation temperatures 1123-1213 K, strain rate 0.1 s-1 and the strain within 0.7, and the maximum m value occurs at deformation temperature 1183 K and strain rate 0.01 s-1 because the microstructure of primary α phase is fine and equiaxed grain. However, the strain hardening exponent decreases with the increase of strain at strain rate 0.01 s-1 due to the combination with work hardening and thermal softening. The morph of primary α phase changes from strip to equiaxed grain with the increase of deformation temperature, and it is of slight oriented characteristic with the increase of strain rate, which is not beneficial for the grain boundary sliding and rotation. The influence of strain on the morph and volume fraction of primary α phase is less, but it is significant for secondary α phase.

基金项目：

李波（1981-），女，硕士，工程师

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