(1. 沈阳理工大学 材料科学与工程学院,沈阳 110159;
2. 东北财经大学 金融学院,大连 116025)
摘 要: 在变形温度为260~410 ℃、应变速率为0.001~10 s-1条件下,对AZ80镁合金进行热拉伸实验,测试AZ80镁合金的真应力-真应变曲线;依据Arrhenius本构方程形式,确定AZ80镁合金热变形过程的本构关系模型;提出一种新的加工硬化率方法,当加工硬化率函数对应变(ε)求一阶导数后的函数取最小值时所对应的应变值,即为临界应变(εc)。采用新的加工硬化率方法,确定AZ80镁合金在不同变形条件下动态再结晶的临界应变和临界应力;研究热变形工艺参数对临界应变和临界应力的影响规律;确定AZ80镁合金热变形过程中的临界应变、临界应力、稳定应变与Z参数的关系模型。模型计算结果与Sellars模型结果相吻合。
关键字: AZ80镁合金;加工硬化率;动态再结晶;临界条件
(1. School of Materials Science and Engineering, Shenyang Ligong University, Shenyang 110159, China;
2. Dongbei University of Finance and Economics, Dalian 116025, China)
Abstract:The curves of true stress-strain of AZ80 magnesium alloy are tested by thermal tensile method, which the ranges of temperature is from 260 to 410 oC and strain rates is from 0.001 to 10 s-1. According to the Arrhenius equation,the constitutive model of AZ80 magnesium alloy at thermal deformation was determined. A new work hardening rate method was proposed. When the derivative of work hardening rate function takes minimum value, the corresponding strain is the critical strain(εc). The work hardening rate method was used to determine the critical strain and critical stress of dynamic recrystallization under different deformation. The relation model of critical strain and critical stress and steady strain with Zener-Hollomn parameters (Z) were established. Calculation results of the critical strain model are in good agreement with that of Sellar’s model.
Key words: AZ80 magnesium alloy; working hardening rate; dynamic recrystallization; critical condition