应用加工硬化率研究TA15钛合金β区变形的动态再结晶临界条件

Study on Critical Strains of Dynamic Recrystallization during β Process in TA15 Titanium Alloy using Working Hardening Rate

基于位错理论探讨了材料大应变条件下的加工硬化率曲线及动态再结晶的拐点判据,利用在变形温度1050～1100℃、应变速率0.001～1s-1条件下等温恒应变速率压缩试验获得的应力-应变数据,采用加工硬化率处理方法,研究了TA15钛合金β区变形的动态再结晶临界条件,并应用Zener-Hollomon参数建立了临界应变模型。结果表明,TA15钛合金在本试验条件下呈现两种曲线特征类型的应力-应变曲线,其θ-σ曲线均呈现拐点及-θ/σ-σ曲线上出现最小值;临界应变与峰值应变之间具有一定的相关性,即εc/εp=0.62;临界应变与Z参数之间的函数关系为εc=1.72×10-2Z0.0605。

Work hardening rate curve under the large strain and inflection point criterion of dynamic recrystallization from the curve for determining critical strain theory was analyzed based on dislocation. The dynamic recrystallization critical conditions for onset of DRX during β process were established according to the work hardening rate approach,using experimental data obtained during compression deformation in the range of deformation temperature 1050～1100℃ and strain rate 0.001~1s-1. Furthermore,the predicting model of critical strain was determined by the Zener-Hollomon parameter approach. The results indicate that two type of stress-strain curve is observed under present deformation conditions.The critical conditions leads to the appearance of an inflection point in the θ-σ curve and to a minimum value of -θ/σ when the critical state is attained. There are linear relation between critical strain and peak strain,i.e. εc/εp=0.62.The predicting model of critical strain were established by the function of εc=1.72×10-2Z0.0605.