(1. 湖南大學(xué) 材料科學(xué)與工程學(xué)院，長沙 410082；2. 湖南大學(xué) 汽車車身先進(jìn)設(shè)計制造國家重點(diǎn)實(shí)驗(yàn)室，長沙 410082)
摘 要: 在應(yīng)變速率為0.01~50 s−1、溫度為300~450 ℃的條件下，在Gleeble−3500熱模擬機(jī)上對AZ80鎂合金的高溫?zé)釅嚎s變形特性進(jìn)行研究。實(shí)驗(yàn)得出變形過程中的真應(yīng)力應(yīng)變曲線，并利用本構(gòu)方程對流變應(yīng)力值進(jìn)行修正，進(jìn)而利用修正后的應(yīng)力值得出本實(shí)驗(yàn)本構(gòu)方程中的系列常量；實(shí)驗(yàn)還分析溫度、應(yīng)變速率及應(yīng)變量對微觀組織的影響。結(jié)果表明：變形過程中的應(yīng)力值隨溫度的升高而降低，隨應(yīng)變速率的升高而升高，且修正后的應(yīng)力值高于未修正值；變形過程中發(fā)生動態(tài)再結(jié)晶且晶粒平均尺寸隨變形參數(shù)的不同而改變，其自然對數(shù)隨Zener-Hollomon(Z)參數(shù)的自然對數(shù)的升高呈線性降低。
關(guān)鍵字: AZ80鎂合金；熱變形；流變應(yīng)力；本構(gòu)方程
（1. College of Materials Science and Engineering, Hunan University,Changsha 410082, China;2. State Key Laboratory of Advanced Design and Manufacture for Vehicle Body,Hunan University, Changsha 410082, China）
Abstract:Hot compression tests of AZ80 magnesium alloy were performed on Gleeble-3500 at strain rates ranged in 0.01−50 s−1 and deformation temperature ranged in 300−350 ℃. The true stress/true strain curves were obtained in the tests. The flow stress was corrected by the constitutive equations and the constants in the constitutive equations were calculated using the corrected stress. The relation between stress and strain is obviously affected by strain rate and deformation temperature. The results show that the flow stress increases with the increase of strain rate at constant temperature, and decreases with the increase of deformation temperature at constant strain rate. The corrected flow stress is generally higher than the uncorrected value. The dynamic recrystallization takes place during the deformation process, and the average dynamically recrystallized grain size changes with deformation variables. A linear relationship between ln Z and ln dr is obtained (Z is Zener-Hollomon parameter and dr is average grain size
Key words: AZ80 magnesium alloy; hot compression deformation; flow stress; constitutive equation
