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利用Gleeble-1500热力模拟试验机,获得了20 vol%TiC-弥散铜复合材料在温度450~850℃、应变速率0.001~1 s-1的真应力-应变数据。采用非线性拟合法建立了真应力-应变曲线的非线性方程,求得加工硬化率;研究了该材料的动态再结晶,并采用Zener-Homon参数建立了临界应变模型。结果表明,非线性方程能精确表征真应力-应变曲线,该材料的真应力-应变曲线主要以动态再结晶软化机制为特征;该材料的lnθ-ε曲线出现拐点,-(lnθ)/ε-ε曲线出现极小值说明材料发生了动态再结晶;临界应变均随应变速率的增加及变形温度的降低而增大,且临界应变与峰值应变之间具有相关性,即εc=0.5276εp;临界应变与Z参数之间的函数关系为εc=7.91×10-3Z0.0736。
The true stress-strain data of 20 vol% TiC-dispersed copper composites at 450 ~ 850 ℃ and strain rate of 0.001 ~ 1 s-1 were obtained by Gleeble-1500 thermal simulation test machine. The non-linear fitting method was used to establish the nonlinear equation of true stress-strain curve, and the work hardening rate was obtained. The dynamic recrystallization of the material was studied and the critical strain model was established by Zener-Homon parameter. The results show that the nonlinear equation can accurately characterize the true stress-strain curve. The true stress-strain curve of the material is mainly characterized by the dynamic recrystallization softening mechanism. The lnθ-ε curve of the material has an inflection point, - (lnθ) / The minimum value of ε-ε curve indicates the dynamic recrystallization occurred in the material. The critical strain increases with the increase of strain rate and the decrease of deformation temperature, and the correlation between critical strain and peak strain is εc = 0.5276εp ; The critical strain and Z parameters as a function of εc = 7.91 × 10-3Z0.0736.