Modeling and Finite Element Analysis for the Dynamic Recrystallization Behavior of Ti-5Al-5Mo-5V-3Cr-1Zr Near β Titanium Alloy during Hot Deformation

Abstract

Evolution for the dynamic recrystallization (DRX) volume fraction of Ti-5Al-5Mo-5V-3Cr-1Zr near β titanium alloy during hot deformation was characterized by using the Johnson-Mehl-Avrami-Kolmogorov (JMAK) equation. To determine the equation parameters, a series of thermal simulation experiments at the temperature of 1023-1098 K and strain rate of 0.001-1 s-1 to the true strain of 0.7 were conducted to obtain the essential data about stress σ and strain ϵ. By further transforming the relationship of σ versus ϵ into the relationship of strain hardening rate dσ/dϵ versus σ, two characteristic strains at the beginning of DRX (critical strain ϵc) and at the peak stress (peak strain ϵp) were identified from the dσ/dϵ-σ curves. Sequentially, the parameters in the JMAK equation were determined from the linear fitting of the different relationships among critical strain ϵc, peak strain ϵp and deformation conditions (including temperature T, strain rate ϵ $\dot\varepsilon $ and strain ϵ). The as-obtained JMAK equation was expressed as XDRX=1-exp[-0.0053((ϵ-ϵc)/ϵc)2.1], where ϵc=0.6053ϵp and ϵp=0.0031 ϵ $\dot\varepsilon $ 0.0081exp(28,781/RT). Finally, the JMAK equation was implanted into finite element program to simulate the hot compression of thermal simulation experiments. The simulation predictions and experimental results about the DRX volume fraction distribution showed a good consistency.