(1. 河南科技大學(xué)材料科學(xué)與工程學(xué)院，洛陽(yáng) 471023；
2. 河南科技大學(xué)有色金屬共性技術(shù)河南省協(xié)同創(chuàng)新中心，洛陽(yáng) 471023)
摘 要: 采用Gleeble-1500D型熱/力模擬試驗(yàn)機(jī)在變形溫度300~450 ℃、應(yīng)變速率0.005~1 s-1條件下對(duì)AZ41M鎂合金進(jìn)行熱模擬壓縮試驗(yàn)。用計(jì)算加工硬化率的方法處理試驗(yàn)數(shù)據(jù)，再結(jié)合lnθ-ε曲線的拐點(diǎn)及–？(lnθ)/？ε-ε曲線最小值判據(jù)，建立合金熱變形過(guò)程中的動(dòng)態(tài)再結(jié)晶臨界應(yīng)變模型。根據(jù)熱壓縮實(shí)驗(yàn)數(shù)據(jù)，分析溫度和應(yīng)變速率等工藝參數(shù)對(duì)合金動(dòng)態(tài)再結(jié)晶的影響。結(jié)果表明：在該實(shí)驗(yàn)條件下，AZ41M鎂合金的lnθ-ε曲線均具有拐點(diǎn)特征，對(duì)應(yīng)的-？(lnθ)/？ε-ε曲線均出現(xiàn)最小值，該最小值所對(duì)應(yīng)的應(yīng)變即為臨界應(yīng)變?chǔ)?SUB>c，得到合金臨界應(yīng)變預(yù)測(cè)模型；臨界應(yīng)變隨變形溫度的降低和應(yīng)變速率的增加而增大，且峰值應(yīng)變?chǔ)?SUB>p和臨界應(yīng)變?chǔ)?SUB>c的比值滿足εp/εc = 1.97。
關(guān)鍵字: AZ41M鎂合金；加工硬化率；動(dòng)態(tài)再結(jié)晶；臨界條件；組織演變
（1. School of Materials Science and Engineering,
Henan University of Science and Technology, Luoyang 471023, China;
2. Collaborative Innovation Center of Nonferrous Metals of Henan Province,
Henan University of Science and Technology, Luoyang 471023, China）
Abstract:The hot simulation compression tests of AZ41M magnesium alloy were conducted at deformation temperature in the range of 300-450 ℃ and strain rate in the range of 0.005-1 s-1 with the Gleeble-1500D thermal-mechanical simulation test machine. The critical strain model of dynamic recrystallization for AZ41M magnesium alloy during hot deformation was obtained by computing the work hardening rate θ from initial experimental data and combining with the inflection point criterion of lnθ-ε curves and the minimum value criterion of -？(lnθ)/？ε-ε curves. The influences of temperature and strain rate on the dynamic recrystallization were investigated based on the experimental data. The results show that an inflection point presents in the lnθ-ε curve and a minimum value appears in the corresponding –？(lnθ)/？ε-ε curve when the critical state of AZ41M magnesium alloy is attained, the strain that relates to the minimum value is the critical strain εc. The predicting model of critical strain is described. The critical strain increases with the decrease of deformation temperature and the increase of strain rate, and the ratio of peak strain (εp) and critical strain εc is 1.97.
Key words: AZ41M magnesium alloy; work hardening rate; dynamic recrystallization; critical condition; microstructure evolution
