CAJ | 학술논문

基于新型亚稳β钛合金Ti2448在温度1023～1123 K、应变速率63～0.001 s-1下的等温热压缩流动应力曲线特征,构建能够完整描述该合金流动应力与应变、应变速率、变形温度之间关系的本构模型.在此过程中,通过基于统一黏塑形理论改进双曲正弦函数,构建合金在高应变速率(≥1 s-1)下发生动态回复(DRV)的模型;通过对标准的Avrami方程进行简化,表征了Ti2448在低应变率＜1 s-1)下发生的动态再结晶(DRX)软化机制.最终通过应用全局优化求解非线性方程的新方法确定模型中的相关参数.根据所建模型得到的预测曲线和实验曲线吻合得较好,能够有效预测Ti2448在热变形过程中的流动应力,为构建亚稳β钛合金热变形本构模型提供一种有效的方法.
기우신형아은β태합금Ti2448재온도1023～1123 K、응변속솔63～0.001 s-1하적등온열압축류동응력곡선특정,구건능구완정묘술해합금류동응력여응변、응변속솔、변형온도지간관계적본구모형.재차과정중,통과기우통일점소형이론개진쌍곡정현함수,구건합금재고응변속솔(≥1 s-1)하발생동태회복(DRV)적모형;통과대표준적Avrami방정진행간화,표정료Ti2448재저응변솔＜1 s-1)하발생적동태재결정(DRX)연화궤제.최종통과응용전국우화구해비선성방정적신방법학정모형중적상관삼수.근거소건모형득도적예측곡선화실험곡선문합득교호,능구유효예측Ti2448재열변형과정중적류동응력,위구건아은β태합금열변형본구모형제공일충유효적방법.
The constitutive model was developed to describe the relationship among flow stress,strain,strain rate,and deformation temperature completely,based on the characteristics of flow stress curves for a new kind of metastableβ Ti2448 titanium alloy from isothermal hot compression tests,in a wide range of temperatures (1023-1123 K) and strain rates (63-0.001 s-1).During this process,the adopted hyperbolic sine function based on the unified viscoplasticity theory was used to model the flow behavior of alloy undergoing flow softening caused by dynamic recovery (DRV) at high strain rates (≥1 s-1).The standard Avrami equation was adopted to represent the softening mechanism attributed to dynamic recrystallization (DRX) at low strain rates (＜1 s-1).Additionally,the material constants were determined by optimization strategy,which is a new method to solve the nonlinear constitutive equation.The stress-strain curves predicted by the developed constitutive model agree well with the experimental results,which confirms that the developed constitutive model can give an accurate estimate of the flow stress of Ti2448 titanium alloy and provide an effective method to model the flow behavior of metastableβ titanium alloys during hot deformation.