不同加热制度下TA15钛合金变形组织及微观取向分析

Analysis of Microstructure and Orientation of Deformed TA15 Titanium Alloy with Different Heating Institution

在Gleeble—3500型热模拟机上对近α型TA15钛合金进行等温压缩实验,研究不同加热制度对TA15钛合金热变形后微观组织、晶界取向差和晶粒取向的影响。研究结果表明,在两相区(900℃)变形时,常规加热制度下变形后TA15钛合金微观组织主要由原始等轴α相、再结晶α相和马氏体α'相组成,当晶界取向差为40°、60°和90°左右时晶界比例出现峰值;而β相区加热制度下合金变形微观组织主要由片状马氏体α'相、β相和晶界处细小的α相组成,当晶界取向差为60°和90°左右时晶界比例出现峰值,晶粒择优取向性增强。在β单相区(1 050℃)变形时,常规加热制度下变形后合金微观组织中β晶粒晶界清晰,集束特征明显;而β相区加热制度下合金变形微观组织主要由长宽比较大的α'相组成,原始β晶粒消失,当晶界取向差为60°和90°左右时晶界比例出现峰值,晶粒择优取向性减弱,各向同性增强。

Isothermal compression tests of near-α TA15 titanium alloy were carried out on Gleeble 3500 thermal simulation machine. The influence was investigated of heating institution on microstructure and grain boundary or grain orientation of the deformed TA15 titanium alloy. The results show that when the alloy is deformed in the two-phase region （900 ℃）,its microstructure with ordinary heating institution consists of primary equiaxed a phase, recrystallized a phase and martensite α＇ phase, and its grain boundary ratio exhibits a peak value at the grain boundary misorientation of 40°, 60° and 90°. However, its micro- structure with β phase zone heating institution consists of lamellar martensite α＇ phase,β phase and interg- ranular a phase,and its grain boundary ratio exhibits a peak value at the grain boundary misorientation of 60° and 90° with enhanced grain preferred orientation. When the alloy is deformed in β single phase region （1 050 ℃）, its microstructure with ordinary heating institution has clear β grain boundaries and obvious cluster characteristics. However,its microstructure with βphase zone heating institution mainly consists of α＇ phase with greater length to width ratio, the original β grains disappear, and grain boundary ratio exhibits a peak value at the grain boundary misorientation of 60° and 90° with weakened grain preferred orientation and enhanced isotropics.