(1. 哈爾濱理工大學(xué)材料科學(xué)與工程學(xué)院，哈爾濱 150080；
2. 黑龍江科技大學(xué)材料科學(xué)與工程學(xué)院，哈爾濱 150022；
3. 哈爾濱焊接研究院有限公司，哈爾濱 150028)
摘 要: 采用Gleeble-3800型熱模擬試驗機對擠壓鑄造態(tài)AZ91D鎂合金進(jìn)行了熱壓縮實驗，研究在溫度250~400 ℃、應(yīng)變速率0.001~1 s-1條件下擠壓鑄造態(tài)AZ91D鎂合金的流變應(yīng)力行為，同時利用金相分析(OM)、透射分析(TEM)和電子背散射分析(EBSD)對其變形微觀組織進(jìn)行了研究，建立其本構(gòu)方程和熱加工圖。結(jié)果表明：應(yīng)變速率和溫度對擠壓鑄造態(tài)AZ91D鎂合金的流變應(yīng)力行為有顯著的影響；擠壓鑄造態(tài)AZ91D鎂合金最合適的加工范圍是360~400 ℃、0.001~1 s-1與270~360 ℃、0.001~0.01 s-1；在應(yīng)變速率0.1 s-1的條件下，隨著溫度升高，動態(tài)再結(jié)晶起始的臨界應(yīng)變由0.11降至0.02，形變孿晶與位錯逐漸被動態(tài)再結(jié)晶取代，擠壓鑄造態(tài)AZ91D鎂合金的變形機制由滑移和孿生轉(zhuǎn)向滑移與動態(tài)再結(jié)晶相協(xié)調(diào)。
關(guān)鍵字: AZ91D鎂合金；流變應(yīng)力；動態(tài)再結(jié)晶
（1. School of Materials Science and Engineering, Harbin University
of Science and Technology,Harbin 150080,China;
2. School of Materials Science and Engineering,
Heilongjiang University of Science and Technology, Harbin 150022, China;
3. Harbin Welding Institute Limited Company,
Harbin 150028, China）
Abstract:The flow stress behavior of squeeze-cast AZ91D alloy was studied using thermal simulation tests on a Gleeble-3800 machine at the temperature range of 250-400 ℃ and strain rate of 0.001-1 s-1. The microstructure was investigated by using optical microscopy (OM), transmission electron microscopy (TEM) and electron back scatter diffractometry (EBSD), and the constitutive equation and thermal processing map of the Squeeze-cast AZ91D alloy was established. The results show that the effect of strain rate and temperature on the flow stress behavior is significant. The thermal processing map exhibits that the suitable processing conditions as follows: 360-400 ℃, 0.001-1 s-1 and 270-360 ℃, 0.001-0.01 s-1. The critical strain for the initiation of dynamic recrystallization decreases from 0.11 to 0.02 with the increase of temperature at 0.1 s-1. The deformation twins and dislocations are gradually replaced by dynamically recrystallized grains. The deformation mechanism of squeeze cast AZ91D magnesium alloy changes from slip and twinning to the coordination of slip and dynamic recrystallization.
Key words: AZ91D magnesium alloy; flow stress; dynamic recrystallization
