论文部分内容阅读
借鉴正挤压与多道次等通道挤压的特点提出了挤压(Extrusion)-剪切(Shear)复合挤压工艺(简称ES),制造了多副适合工业卧式挤压机的ES变形组合凹模,进行了ES挤压和普通挤压实验。构建了ES挤压和普通挤压的三维有限元热力耦合模型及数值模拟条件,对ES挤压过程的挤压力、累积应变演化进行了计算机模拟仿真。通过对坯料的应力状态进行了计算机模拟分析,发现ES挤压过程局部坯料受到四向压应力,ES挤压与普通正挤压相比可以显著提高镁合金变形过程的累积应变,因此可以更有效的细化晶粒。针对ES挤压和普通挤压棒料的不同位置进行了微观组织观察,发现在挤压温度为370℃、挤压比为12时ES挤压可以有效的细化晶粒,不仅可以细化棒材表层晶粒,心部也得到了细化。
Based on the characteristics of positive extrusion and multi-pass extrusion, Extrusion-Shear composite extrusion (ES) was proposed to produce a number of ES deformations suitable for industrial horizontal extruders Combination of die, ES extrusion and ordinary extrusion experiments. The three-dimensional finite element thermal coupling model and numerical simulation conditions of ES extrusion and normal extrusion were established. The extrusion and cumulative strain evolution of ES extrusion were simulated by computer. Through the computer simulation analysis of the stress state of the billet, it is found that the local billet of the ES extrusion process is subjected to four-direction compressive stress. Compared with the normal extrusion, the ES extrusion can significantly increase the cumulative strain of the deformation process of the magnesium alloy and thus can be more effective Of the refined grains. According to the microstructure observation of ES extrusion and ordinary extrusion bar at different positions, it was found that the ES extrusion can effectively refine the grains at the extrusion temperature of 370 ℃ and the extrusion ratio of 12, which not only can refine the rods Material surface grain, the heart has also been refined.