(1. 上海交通大學(xué) 材料科學(xué)與工程學(xué)院，上海 200240；
2. 上海交通大學(xué) 輕合金精密成型國(guó)家工程研究中心和金屬基復(fù)合材料國(guó)家重點(diǎn)實(shí)驗(yàn)室，上海 200240；
3. 上海寶鋼研究院，上海 200940)
摘 要: 采用Thermecmastor-Z 熱模擬試驗(yàn)機(jī)在變形溫度為200~520 ℃、應(yīng)變速率為2~60 s-1 條件下對(duì)AZ31B 鎂合金厚板進(jìn)行熱壓縮變形試驗(yàn)，壓縮變形量為60%。結(jié)合變形后的微觀組織以及熱壓縮真應(yīng)力-真應(yīng)變曲線，分析應(yīng)變速率和變形溫度等工藝參數(shù)對(duì)其微觀組織演變的影響。結(jié)果表明：當(dāng)變形溫度高于320 ℃時(shí)，AZ31B 鎂合金的真應(yīng)力-真應(yīng)變曲線呈現(xiàn)典型的動(dòng)態(tài)再結(jié)晶特性。當(dāng)應(yīng)變速率一定時(shí)，流變應(yīng)力隨溫度升高而降低；當(dāng)變形溫度一定時(shí)，流變應(yīng)力在高溫低應(yīng)變速率(低于15 s-1)下隨應(yīng)變速率增大而增大。變形后的微觀組織顯示，壓縮變形過程中發(fā)生了明顯的動(dòng)態(tài)再結(jié)晶，動(dòng)態(tài)再結(jié)晶體積分?jǐn)?shù)隨應(yīng)變速率的增加而增大。另外，變形組織的均勻性受變形溫度的影響十分顯著。在熱壓縮實(shí)驗(yàn)的基礎(chǔ)上，在溫度為300~330 ℃時(shí)對(duì)板材進(jìn)行單道次大壓下量的熱軋，獲得的板材具有均勻細(xì)小的晶粒及優(yōu)異的力學(xué)性能。
關(guān)鍵字: AZ31B 鎂合金；高應(yīng)變速率；壓縮變形；微觀組織；動(dòng)態(tài)再結(jié)晶
（1. School of Materials Science and Engineering,Shanghai Jiao Tong University,Shanghai 200240,China;
2. National Engineering Research Center of Light Alloys Net Forming and
State Key Laboratory of Metal Matrix Composite,Shanghai Jiao Tong University,Shanghai 200240,China;
3. Shanghai Baosteel Research Institute,Shanghai 200940,China）
Abstract:The compression deformation behaviors of AZ31B thick plate at different deformation temperatures of 200-520 ℃ and high strain rates of 2-60 s-1 were studied by using Thermecmastor-Z hot simulation equipment with a strain of 60%. The influence of deformation temperature and strain rate on the microstructure evolution based on the microstructures after deformation and true stress-true stain curve after hot compression was investigated. The results show that true stress-true strain curve is a normal shape for hot working with dynamic recrystallization when deformation temperature is higher than 320 ℃. And the flow stress decreases with increasing temperature at a given strain rate,while it increases with increasing strain rate at a given temperature and a strain rate lower than 15 s-1. The microstructure observation also suggests that dynamic recrystallization takes place obviously during the deformation process. The volume fraction of dynamic recrystallization grains increases with increasing strain rate. In addition,distinct distribution of gains exists in the samples deformed at various temperatures. Based on the hot compression experiment results,AZ31B rolling sheet was processed at 300-330 ℃ and at large reduction per pass. The obtained AZ31B sheet shows fine grain size and excellent mechanical properties.
Key words: AZ31B Mg alloy; high strain rate; compression deformation; microstructure; dynamic recrystallization
