(1. 重慶理工大學 材料科學與工程學院，重慶 400050；
2. 重慶大學 材料科學與工程學院，重慶 400044；
3. 重慶科技學院 冶金與材料學院，重慶 401331；
4. 陸軍勤務(wù)學院 化學與材料學院，重慶 401311)
摘 要: 為研究鎂合金圓管擠壓成形薄壁中空方管的可行性及其性能，本文通過擠壓-剪切復合成形工藝將AZ31鎂合金圓管坯料直接制備成厚度為2 mm的薄壁中空方形管材。結(jié)合DEFORM-3D軟件對不同溫度下鎂合金方管成形過程中成形載荷、擠壓速度、等效應變等進行了數(shù)值模擬。結(jié)果表明：溫度的大小影響成形載荷的分布，合適的成形速度與溫度有利于鎂合金方管的成形。通過擠壓-剪切復合工藝可直接一道次成形薄壁中空方管，且成形方管的晶粒尺寸得到有效細化；在400 ℃下成形方管的屈服強度約為230 MPa，伸長率約為20%，斷裂方式為準解理斷裂；在動態(tài)再結(jié)晶和較大的剪切作用下，成形方管的基面織構(gòu)分散程度較高，強度明顯弱化，其綜合性能得到提高。在擠壓-剪切復合成形過程中，可以通過降低變形速度和提高變形溫度來獲得良好性能的鎂合金方管。
關(guān)鍵字: 鎂合金；薄壁中空型材；擠壓剪切；數(shù)值模擬
（1. School of Materials Science and Engineering, Chongqing University of Technology, Chongqing 400050, China;
2. School of Materials Science and Engineering, Chongqing University, Chongqing 400044, China;
3. School of Metallurgy and Materials, Chongqing University of Science and Technology, Chongqing 401331, China;
4. School of Chemistry and Materials, Army Service College, Chongqing 401311, China）
Abstract:In order to study the feasibility and properties of magnesium alloy round tube extrusion forming thin-walled hollow square tube, the round tube billet of AZ31 magnesium alloy was directly prepared into thin-walled hollow square tube with thickness of 2 mm by extrusion-shear composite forming process in this paper. DEFORM-3D software was used to simulate the forming load, extrusion speed and equivalent strain of the square tube forming at different temperatures. The results show that the temperature has great influence on the distribution of forming load, and the proper extrusion speed is beneficial to the formation of magnesium alloy square tube. The thin-walled hollow square tubes can be directly fabricated by one-pass with extrusion-shear composite process, and the grain size of square tubes can be effectively refined. At 400 ℃, the yield strength of square tube is about 230 MPa, the elongation is about 20%, and the fracture mode is quasi-cleavage fracture. And due to dynamic recrystallization and large shear effect, the dispersion degree of basal plane texture of square tube is higher, the strength is obviously weakened, and the comprehensive performance is obviously improved. The thin-walled hollow square tube with good properties can be obtained by reducing the extrusion speed and increasing the deformation temperature during the extrusion-shear composite forming process.
Key words: magnesium alloy; thin wall hollow profile forming; extrusion-shear; numerical simulation
