(華南理工大學(xué) 機(jī)械與汽車工程學(xué)院 國家金屬材料近凈成形工程技術(shù)研究中心，廣州 510640)
摘 要: 采用一種新型劇塑性變形工藝—T型通道擠壓(TCP)對ZK60鎂合金在673 K下以A和Bc兩種路徑進(jìn)行1~4道次擠壓變形，通過光學(xué)顯微鏡觀察變形鎂合金的顯微組織，并對TCP變形鎂合金的不同部位在應(yīng)變速率4×10−3 s−1時進(jìn)行室溫拉伸性能測試。結(jié)果表明：塑性變形最大的部位是試樣中間部位的最底部，其組織特征為細(xì)小晶粒包圍著大晶粒，大晶粒呈拉長的流線狀；4道次變形后，A路徑的平均晶粒尺寸由退火態(tài)時的88.5 μm細(xì)化至2.4 μm，Bc路徑的平均晶粒尺寸則細(xì)化至4.6 μm，但組織更均勻；同時，在相同道次TCP變形后，A路徑變形合金的屈服強(qiáng)度都高于Bc路徑變形合金的，但前者的抗拉強(qiáng)度和塑性卻低于后者的；此外，試樣最底部的抗拉強(qiáng)度和屈服強(qiáng)度均高于試樣頂部的，經(jīng)Bc路徑2道次變形后試樣底部與頂部的抗拉強(qiáng)度和屈服強(qiáng)度分別相差39.5和43.1 MPa，而經(jīng)4道次變形后試樣兩個部位的抗拉強(qiáng)度和屈服強(qiáng)度分別只相差21.2和11.7 MPa。
關(guān)鍵字: 鎂合金；T型通道擠壓；劇塑性變形；顯微組織；力學(xué)性能
ZK60 magnesium alloy processed by T-shape channel pressing
（National Engineering Research Center of Near-Net-Shape Forming for Metallic Materials,
School of Mechanical and Automotive Engineering, South China University of Technology, Guangzhou 510640, China）
Abstract:ZK60 magnesium alloy was deformed by a new process of severe plastic deformation(SPD)—T-shape channel pressing (TCP) from 1 pass to 4 passes at 673 K using route, A and Bc. The microstructure of TCPed ZK60 was observed by optical microscopy, and the mechanical properties of different TCPed parts were tested with strain rate of 4×10−3 s−1 at room temperature. The results show that the biggest plastic deformation is located at the bottom of sample, and the microstructure character is coarse grains surrounded by fine grains, and the coarse grains are elongated to be streamline. After 4 passes, the average grain size is refined from 88.5 μm of the as-cast alloy to 2.4 μm for the alloy by route A, and to 4.6 μm for alloy by route Bc with more homogeneous microstructure. Meanwhile, at the same pass, the yield strength for alloy by route A is higher than that of the alloy by route Bc, but the tensile strength and ductility of the former alloy are lower than those of the latter. In addition, the tensile strength and yield strength at the bottom are higher than those at the top. The differences of tensile strength and yield strength between the bottom and top of the alloy deformed by route Bc are 39.5 MPa and 43.1 MPa for 2 passes, and only 21.2 MPa and 11.7 MPa for 4 passes, respectively.
Key words: magnesium alloy; T-shape channel pressing; severe plastic deformation; microstructure; mechanical property
