Incoloy825合金热变形过程中的本构模型和特殊晶界演变

Constitutive Models and Evolution of Special Grain Boundary During Hot Deformation of Incoloy825 Alloy

采用原始JC模型、修正JC模型和应变补偿Arrhenius方程,描述了Incoloy825合金在不同温度(950~1150℃)和应变速率(1~10 s)下经摩擦和温升修正后的应力-应变曲线。结果表明,修正后曲线具有明显的动态再结晶特征。与原始JC模型和修正的JC模型相比,Arrhenius应变补偿模型更适合于描述Incoloy825合金热变形过程中的应力应变行为。温度和应变速率对特殊晶界的演变有显著影响。特殊晶界长度分数与动态再结晶分数呈正相关。与冷轧后退火处理工艺相比,热变形工艺调控的特殊晶界长度分数较低,热变形工艺不适合用来调整特殊晶界分数,其原因是在热变形过程中动态再结晶的大量形核造成较小的晶粒团簇。

The original JC model, modified JC model and strain compensated Arrhenius equation were used to describe the stressstrain curves of Incoloy825 alloy at different temperatures(950~1150 ℃) and strain rates(1~10 s) after friction and temperature rise modification. The results show that the modified curve shows obvious characteristics of dynamic recrystallization. Compared with the original JC model and the modified JC model, the Arrhenius model of strain compensation is more suitable to describe the stressstrain behavior of Incoloy825 alloy during hot deformation. Temperature and strain rate have significant effects on the evolution of special grain boundaries. The length fraction of special grain boundary is positively correlated with the dynamic recrystallization fraction. Compared with the case of annealing after cold rolling, the special grain boundary fraction regulated by hot deformation process is relatively low. Hot deformation process is not conducive to the improvement of special grain boundary fraction, because the formation of dynamic recrystallization during hot deformation leads to small twin related domain(TRD) size.