( 1. 北京有色金屬研究總院 北京 100088;
2. Brunel University, Uxbridge, Middle Sex U138 3PH, UK;
3. 北京科技大學 新金屬材料國家重點實驗室， 北京 100083)
摘 要: 采用雙螺旋流變鑄造工藝制備了鎂合金AZ31B的棒坯， 利用Gleeble-3000型熱/力模擬機研究了流變鑄造和普通連鑄棒坯在變形溫度為250~400 ℃， 變形速率為0.001~5 s-1， 最大變形量為60%時的熱壓縮變形行為。 分析了材料流變應(yīng)力與變形量、 變形溫度和應(yīng)變速率之間的關(guān)系， 比較了兩種不同鑄造工藝對熱塑性變形行為的影響。 結(jié)果表明： 流變鑄造坯料在變形過程中的形變均勻性明顯優(yōu)于普通鑄造的， 因此不需預處理即可直接進行塑性成型； 350 ℃以上熱變形流變鑄造坯料的變形抗力明顯小于普通鑄造坯料的； 流變鑄造使AZ31B合金的塑性加工性能得到改善； 產(chǎn)生這種差別的主要原因是普通鑄造坯料組織為粗大樹枝晶， 而流變鑄造坯料組織為細小等軸晶。
關(guān)鍵字: 鎂合金； 流變鑄造； 熱/力模擬
SHI Li-kai1, CHEN Guo-liang3
（ 1. General Research Institute for Nonferrous Metals, Beijing 100088, China;
2. Brunel University, Uxbridge, Middle Sex U138 3PH, UK;
3. State Key Laboratory for Advanced Metals and Materials,
University of Science and Technology Beijing, Beijing 100083, China）
Abstract: The billet of magnesium alloy AZ31B was prepared by the method of twin-screw rheo-casting and normal casting. The hot compression of these two kinds of samples at 250-400 ℃ was performed on Gleeble-3000 hot simulator with the strain rates of 0.001-5 s-1, and the maximum deformation of 60%. The relationship among the stress, deformation temperature and strain rate were analyzed and compared. The results show that the deformation of rheo-casting billet is more uniform than that of the normal casting in the compression process, so the rheo-cast billet can be hot deformed directly. The maximum stress of rheo-casting is less than that of the normal casting at above 350 ℃, which means that the billet made by rheo-casting can be deformed easier than normal casting. The reason of the difference is that the microstructure of rheo-casting is composed of uniform, tiny and equal-axial grains; while the microstructure of normal casting is coarse dendrite.
Key words: magnesium alloy; rheo-casting; hot compressive deformation simulation
