(1. 湖南科技大学 难加工材料高效精密加工湖南省重点实验室，湘潭 411201； 2. 湖南科技大学 高温耐磨材料及制备技术湖南省国防科技重点实验室，湘潭 411201； 3. 中南大学 材料科学与工程学院，长沙 410083)
摘 要: 结合传统挤压与弯曲剪切变形的特点提出一种棒-板正挤压-弯曲剪切复合连续变形新工艺，该工艺既可显著细化晶粒又可以弱化织构，极大地改善镁合金的综合力学性能。通过分析该复合变形方式的特点，建立了总挤压力数学模型，对正挤压-弯曲剪切复合成形所需的挤压力进行了系统、完整、准确的表征。根据各分区的变形特点，把实际的正挤压模型类比成等效面积的圆棒挤压模型，并引入形状复杂系数，利用上界法得出各分区的挤压力解析表达式，基于有限元数值模拟对形状复杂系数进行分析求解。最后通过与实验结果的比较得出该模型计算的结果与实际值的误差在5%的范围内，满足工程计算要求。
关键字: 镁合金；正挤压-弯曲剪切复合变形；显微组织；力学性能；形状复杂系数；挤压力
（1. Hunan Provincial Key Laboratory of High Efficiency and Precision Machining of Difficult-to-cut Material, Hunan University of Science and Technology, Xiangtan 411201, China; 2. Hunan Provincial Key Defense Laboratory of High Temperature Wear-resisting Materials and Preparation Technology, Hunan University of Science and Technology, Xiangtan 411201, China; 3. School of Materials Science and Engineering, Central South University, Changsha 410083, China）
Abstract:Combining with the features of traditional extrusion and bending shear deformation, a new technology of rod-plate direct extrusion and bending shear compound deformation was proposed, which can not only significantly refine the grain size, but also weaken the texture, thus improve the mechanical properties of Mg alloys greatly. Based on the analysis of the compound deformation features, the mathematical model of the total extrusion load was established, The extrusion force required for direct extrusion bending shear compound deformation is systematically, completely and accurately characterized. According to the deformation features of each zone, the actual direct extrusion model can be analogized to the equivalent area of extruded bar model, and a complex shape coefficient is introduced. The upper bounding method is used to get analytical expression of the extrusion force of each zone. The complex coefficient of shape is analyzed and solved based on the finite element numerical simulation. Finally, the research result shows that the error range between calculated value from the mathematical model and the actual value is below 5%, which can satisfy the engineering calculation requirement.
Key words: Mg alloys; direct extrusion-bending shear compound deformation; microstructure; mechanical properties; complex shape coefficient; extrusion load
