The influences of shear deformation on the evolutions of the extrusion shear for magnesium alloy
The influences of shear deformation on the evolutions of the extrusion shear for magnesium alloy
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DOI：
10.1007/s00170-014-5999-9
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发表时间：
2014-06
期刊：
影响因子：
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通讯作者：
H. Hu;H. Wang;Z. Zhai;Y.Y. Li;J. Fan;O. Zhongwen
中科院分区：
文献类型：
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作者：
H. Hu;H. Wang;Z. Zhai;Y.Y. Li;J. Fan;O. Zhongwen
提出了一种结合了直接挤压和两道等径挤压特点的新型镁合金挤压-剪切复合挤压工艺。进行了ES工艺和直接挤压试验，设计制造了适用于工业卧式挤压机的直接挤压和ES模具。建立了ES工艺和直接挤压的三维热力学有限元模型和条件。得到了ES过程的挤压力、累积应变、应力和温度演变规律。与直接挤压相比，ES挤压过程的载荷明显增加。ES工艺的最高温度高于直接挤压的最高温度。对钢坯的应力状态进行了计算机模拟分析，结果表明，部分钢坯受到四个方向的压应力作用。与直接挤压法相比，ES挤压法可使镁合金坯料产生累积应变和剪切应力。因此，可以实现更多的晶粒细化。通过对ES工艺和直接挤压棒中心位置的显微组织观察，发现随着挤压温度的升高，晶粒得到了有效细化。发现有限元模拟结果与实验结果有许多相似之处。
A new type of magnesium alloy extrusion-shear (short for ES) composite extrusion technology which combines the characteristics of direct extrusion and two pass equal channel extrusion has been put forward. The experiments of ES process and direct extrusion have been performed, and direct extrusion and ES dies suitable for industrial horizontal extruder have been designed and manufactured. Three-dimensional thermomechanical finite element models and conditions of the ES process and direct extrusion have been established. Extrusion forces and accumulated strains and stresses and temperatures evolution of the ES process have been obtained. The loads of the ES process increase obviously compared with those of direct extrusion. Maximum temperatures during the ES process are higher than those of direct extrusion. The computer simulation analyses of stress state for the billets reveal that part of the billet is exerted in four directions of compressive stress. The ES process could cause cumulative strains and shear stress in magnesium alloy billets than direct extrusion. Therefore, more grain refinements could be achieved. Based on the microstructure observations of center positions for the ES process and direct extrusion rods, grains have been effectively refined with extrusion temperature. It is found that there are many similarities between finite element simulation results and experimental results.