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通过等温热压缩实验对25%B_4C_p/6061Al(体积分数)复合材料的热变形行为和动态再结晶临界条件进行了研究,采用的温度范围为350~500℃,应变速率范围为0.001~1 s~(-1)。应力-应变曲线显示动态再结晶是复合材料热变形过程中主要的软化机制,并采用峰值应力构建了基于Arrhenius形式的本构方程。基于加工硬化率曲线,求解了表示动态再结晶发生的临界应变与临界应力值。结果表明,临界应力与峰值应力存在线性关系:σ_c=0.8374σ_p–0.33708。此外,引入Zener-Hollomon参数描述变形条件对临界条件的影响,得到临界应变与Z参数的关系:ε_c=2.39×10~(-4)Z~(0.11022)。最后,通过θ-ε曲线得到了复合材料完成动态再结晶时的稳态应变,并绘制了动态再结晶图。
The thermal deformation behavior and dynamic recrystallization critical conditions of 25% B_4C_p / 6061Al (volume fraction) composites were investigated by isothermal hot compression experiment at a temperature range of 350 ~ 500 ℃ and a strain rate range of 0.001 ~ 1 s ~ (-1). The stress-strain curves show that dynamic recrystallization is the main softening mechanism during the thermal deformation of composites, and the constitutive equation based on the Arrhenius form is constructed using peak stress. Based on the work hardening curve, the critical strain and the critical stress value, which represent the occurrence of dynamic recrystallization, were solved. The results show that there is a linear relationship between the critical stress and peak stress: σ_c = 0.8374σ_p-0.33708. In addition, the Zener-Hollomon parameter is introduced to describe the effect of deformation conditions on the critical conditions. The relationship between critical strain and Z parameter is obtained: ε_c = 2.39 × 10 ~ (-4) Z ~ (0.11022). Finally, the steady-state strain of the composites after dynamic recrystallization was obtained by θ-ε curve, and the dynamic recrystallization map was drawn.