(1. 湖南科技大學(xué) 高溫耐磨材料及制備技術(shù)湖南省國(guó)防科技重點(diǎn)實(shí)驗(yàn)室，湘潭 411201；
2. 中南大學(xué) 材料科學(xué)與工程學(xué)院，長(zhǎng)沙 410083)
摘 要: 采用 Gleeble-3500熱模擬試驗(yàn)機(jī)，對(duì)預(yù)孿晶AQ80鎂合金在變形溫度為250~400 ℃、應(yīng)變速率為1×10-3~ 5 s-1條件下進(jìn)行熱壓縮實(shí)驗(yàn)。預(yù)孿晶AQ80鎂合金本構(gòu)方程的建立通過Arrhenius雙曲正弦函數(shù)推導(dǎo)而來。基于動(dòng)態(tài)材料模型，建立在應(yīng)變量為0.1、0.3和0.5下的熱加工圖。結(jié)果表明：預(yù)孿晶AQ80鎂合金的流變應(yīng)力隨著變形溫度升高和應(yīng)變速率下降而減小，熱加工圖中耗散峰值(η=48%)區(qū)出現(xiàn)在低溫低應(yīng)變速率范圍(250~280 ℃, 1×10-3 s-1)。結(jié)合熱加工圖和其對(duì)應(yīng)區(qū)域的金相組織進(jìn)行分析得出：應(yīng)變量為0.5的失穩(wěn)區(qū)在溫度為250~400 ℃、應(yīng)變速率為0.1~5 s-1范圍內(nèi)；然而，加工安全區(qū)在溫度為300~400 ℃、應(yīng)變速率在1×10-3~1×10-2 s-1范圍內(nèi)，組織特征表現(xiàn)為動(dòng)態(tài)再結(jié)晶。
關(guān)鍵字: 預(yù)孿晶AQ80鎂合金；熱壓縮變形；本構(gòu)方程；熱加工圖
（1. Hunan Provincial Key Defense Laboratory of High Temperature Wear-resisting Materials and Preparation Technology, Hunan University of Science and Technology, Xiangtan 411201, China;
2. School of Materials Science and Engineering, Central South University, Changsha 410083, China）
Abstract:The hot compression tests of pre-twin AQ80 magnesium alloy were conducted at temperature of 250-400 ℃ and strain rates of 1×10-3 to 5 s-1 by using the Gleeble-3500 hot-simulator. The constitutive equation of pre-twin AQ80 magnesium alloy was constructed by Arrhenius hyperbolic sine function. According to dynamic materials model, the hot processing maps of pre-twin AQ80 magnesium alloy were established for strain of 0.1, 0.3 and 0.5. The results show that the flow stress of pre-twin AQ80 magnesium alloy decreases with the decrease of strain rate and the increase of temperature. The processing maps exhibit one peak η value (48%) region at temperature of 250-280 ℃ and the strain rate of 1×10-3 s-1. Combining with analysis of hot processing map and the corresponding microstructure at each domain, the instability regions were identified to be at the temperature range of 250-400 ℃ and strain rate of 0.1-5 s-1 for billets deformed to strains of 0.5, while the microstructures characteristic mainly show dynamic recrystallization at the temperature of 300-400 ℃ and strain rate of 1×10-3-1×10-2 s-1, which were indicated as safe regions.
Key words: pre-twin AQ80 magnesium alloy; hot compression deformation; constitutive equation; hot processing map
