(1. 重庆理工大学 材料科学与工程学院，重庆 400050；
2. 重庆大学 材料科学与工程学院，重庆 400044；
3. 重庆科技学院 冶金与材料学院，重庆 401331；
4. 陆军勤务学院 化学与材料学院，重庆 401311)
摘 要: 为研究镁合金圆管挤压成形薄壁中空方管的可行性及其性能，本文通过挤压-剪切复合成形工艺将AZ31镁合金圆管坯料直接制备成厚度为2 mm的薄壁中空方形管材。结合DEFORM-3D软件对不同温度下镁合金方管成形过程中成形载荷、挤压速度、等效应变等进行了数值模拟。结果表明：温度的大小影响成形载荷的分布，合适的成形速度与温度有利于镁合金方管的成形。通过挤压-剪切复合工艺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细化；在400 ℃下成形方管的屈服强度约为230 MPa，伸长率约为20%，断裂方式为准解理断裂；在动态再结晶和较大的剪切作用下，成形方管的基面织构分散程度较高，强度明显弱化，其综合性能得到提高。在挤压-剪切复合成形过程中，可以通过降低变形速度和提高变形温度来获得良好性能的镁合金方管。
关键字: 镁合金；薄壁中空型材；挤压剪切；数值模拟
（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
