30%SiCp/2024Al复合材料动态再结晶临界条件

Critical conditions of dynamic recrystallization of 30%SiCp/2024Al composite

采用Gleeble-1500D热模拟试验机对30%SiCp/Al复合材料进行热模拟试验,其变形温度为623~773K、应变速率为0.01~10s-1。采用加工硬化率法对应力-应变数据进行处理,结合lnθ-ε曲线的拐点和（-（lnθ）/ε）-ε）曲线最小值的判据,研究了该复合材料动态再结晶临界条件。结果表明,30%SiCp/2024Al复合材料的真应力-应变曲线主要以动态再结晶软化机制为特征,峰值应力（σp）随变形温度降低或应变速率升高而增加;该材料的lnθ-ε曲线出现拐点,（-（lnθ）/ε）-ε）曲线出现最小值;临界应变（εc）随变形温度升高与应变速率降低而减小,且临界应变与峰值应变（εp）之间具有相关性,即εc=0.563εp;临界应变与Zener-Hollomon参数（Z）之间的函数关系为εc=7.96×10-3Z0.038。

The hot compression tests of 30% Si Cp / Al composite were conducted at deformation temperature of 623-773 K and the strain rate of0. 01-10 s- 1on a Gleeble-1500 D thermal simulator. The critical conditions of dynamic recrystallization for the initiation of DRX during deformation of 30% Si Cp / Al composite were obtained by computation of the strain hardening rate（ θ） from the stress-strain data and introduction of the inflection point criterion of lnθ- ε curves and the minimum value criterion of（- （ lnθ） / ε）- ε） curves. The results indicate that the softening of the dynamic recrystallization characterizes the high-temperature flow stress strain curves of the composites,and the peak stress increases with the decreasing deformation temperature and or the increasing strain rate. The inflection point in the lnθ- ε curve appears and the minimum value of the（- （ lnθ） / ε）- ε） curve is presented when the composite attains to the critical state. The critical strain decreases with the decreasing strain rate and the increasing deformation temperature. There is a linear relationship between critical strain and peak strain,i. e.εc= 0. 563εp. The predicting model of critical strain is described by the function of εc= 7. 96 × 10- 3Z0. 038.