TC4钛合金加工图及其在板材轧制工艺分析中的应用

Processing map of titanium alloy TC4 and its application for plate rolling analyses

TC4钛合金在航空航天工业中有着广泛的应用,热塑性加工中的微观组织演变对其使用性能具有重要的影响。该文通过热-力实验分析,得到TC4合金的加工图,并将加工图信息集成在有限元分析中,对板材轧制工艺进行分析。对TC4钛合金进行等温单向压缩实验获得了材料的流动应力,变形温度为800～1 050℃,应变速率为0.01～20s-1。采用动态材料模型(dynamic material model,DMM)绘制出TC4钛合金的加工图,并通过对压缩的微观组织检查分析验证了加工图的有效性。由加工图可知,在1 000～1 050℃应变速率0.01s-1的区域稳定性最好,为超塑性成形区域,在800～900℃应变速率0.1～20s-1的条件不利于塑性加工,应当避免在此区域加工。通过二次开发,将加工图的信息作为有限元程序DEFORM-2D的后处理变量在成形件中显示,从而直观地显示板材轧制变形不同位置的成形性能。在TC4轧制过程中,板坯基本处于功率耗散效率较高的安全区,有利于材料塑性成形。

The titanium alloy TC4 is widely used in the aerospace industry and the microstructure evolution during hot plastic deformation strongly influences its performance. This study developed a processing map of TC4 using thermal-mechanical tests which was integrated into a finite element program to investigate plate rolling. Flow stress data was obtained by isothermal uniaxial compression of the TC4 titanium alloy for test temperatures of 800 1 050℃ at strain rates from 0.01 to 20 s 1. The TC4 processing map is based on experiment data described by the dynamic material model （DMM） and validated by observations of the deformed microstructures. The processing map shows that the deformationtemperature and speed dramatically intluence the workability of TC4 titanium alloy. The TC4 is very stable at 1 000- 1 050℃ with a strain rate of 0.01 s^-1, but has poor workability at 800 ~ 900℃ with strain rates of 0.1 . 20 s^-1. The processing map is integrated into the post processing module of the fiaite element method （FEM） program DEFORM-2D as a user subroutine. The material formability in various positions of the deformated part can then be checked by the FEM calculations. The plate rolling of TC4 titanium alloy is simulated and the formabilit7 is then analyzed using the processing map.