应用Murty准则优化TC11钛合金高温变形参数

OPTIMIZATION OF HIGH TEMPERATURE DEFORMATION PARAMETERS OF TITANIUM ALLOY TC11 BY USING MURTY CRITERION

在THERMECMASTOR-Z型热模拟试验机上对原始等轴组织的TC11钛合金进行热压缩实验,采用基于Murty准则的加工图技术研究该合金在990—1080℃、0.001—70_s^(-1)变形参数范围内的微观变形机制和流变失稳现象,并优化该合金的高温变形参数.结果表明,α+β两相区的较佳变形参数为990—1008℃、0.001—0.02s^(-1),以990℃、0.001s^(-1)附近为最佳,其变形机制为超塑性.在β单相区,中等变形程度(ε<0.6)下的较佳参数为1030—1080℃、0.001—0.1s^(-1),以1060—1080℃、0.001s^(-1)附近为最佳,其变形机制为动态再结晶;而大变形程度(ε>0.6)下的较佳参数为1020—1060℃、0.004—0.6s^(-1),以1040—1050℃、0.016—0.07s^(-1)附近为最佳,其变形机制也是动态再结晶.失稳区出现在β单相区内,其参数范围为1000—1080℃、4.0—70s^(-1),在该失稳区会出现β晶粒的不均匀变形;应变速率在0.001s^(-1)附近时,在β单相区变形会出现β晶粒的动态粗化.

Hot compression tests of titanium alloy TCll with equiaxed grains were conducted on the THERMECMASTOR-Z hot working simulator. Micro-deformation mechanisms and the manifestations of flow instability were investigated by means of processing map technology based on Murty criterion, and deformation parameters were optimized in the temperature range of 990-1080 ℃and strain rate range of 0.001-70s^-1. The results show that in α ＋β phase field the desired deformation parameters are in the ranges of 990-1008 ℃ and 0.001- 0.02 s^-1 with the deformation mechanism of superplasticity, and the optimum parameters are near 990 ℃ and 0.001 s^-1. In β phase field, the desired parameters are in 1030-1080 ℃ and 0.001-0.1 s^-1 at the strains below 0.6, and 1020-1060 ℃ and 0.004-0.6 s^-1 at the strains beyond 0.6, respectively, in the two regions the deformation mechanism is dynamic recrystallization, and the optimum parameters are respectively in 1060-1080℃, 0.001 s^-1 and 1040-1050℃, 0.016-0.07 s^-1. The region of flow instability occurs in the temperature range of 1000-1080 ℃ and strain rate range of 4.0-70 s^-1 in β phase field, and the manifestation of flow instability is non-uniform deformation of β grains. In β phase field the dynamic growth of grains would occur near the strain rate of 0.001 s^-1.