AZ80镁合金超高压静液挤压成形工艺及性能研究

发布时间：2018-05-07 00:05

本文选题：静液挤压 + 数值模拟　；参考：《南京理工大学》2017年硕士论文

【摘要】：本文对AZ80镁合金超高压静液挤压成形工艺进行研究。首先对超高压静液挤压系统进行了总体方案设计,制定了超高压静液挤压的工艺流程,对关键工艺参数和静液挤压原理开展深入理论研究。制定了大口径镁合金管材和厚壁镁合金管材成形的工艺方案,并对模具进行了详细结构设计。然后采用DEFORM-3D有限元软件对超高压静液挤压进行了数值模拟,得到了挤压筒温度场的分布规律,这对静液挤压温度的研究具有指导意义。对大口径镁合金管材的静液挤压成形过程进行了仿真分析,研究了挤压比对挤压载荷、等效应变和速度场的影响。随着挤压比增大,挤压载荷的峰值压力和平均压力都会随之增大,挤压比对峰值压力的影响更明显。分析了管材成形后的等效应变的分布,等效应变的最大值分布在挤压变形区,材料在该区域主要发生剪切和挤压变形。最后,在40MN卧式静液挤压机下,实现大口径镁合金管材和厚壁镁合金管材的制备,并对管材取样,进行显微组织分析和力学性能测试。静液挤压制品的屈服强度和抗拉强度得到明显提高,但制品延伸率较低。静液挤压后的镁合金管材组织,其晶粒沿挤压方向被拉长,出现亚晶粒,晶粒细化明显。本文还研究了再结晶退火工艺对静液挤压制品性能的影响,这对于进一步改善制品塑性性能具有重要意义。
[Abstract]:In this paper, the hydrostatic extrusion process of AZ80 magnesium alloy under high pressure was studied. At first, the overall scheme design of the EHP hydrostatic extrusion system is carried out, and the process flow of UHP hydrostatic extrusion is established. The key technological parameters and the hydrostatic extrusion principle are deeply studied theoretically. The process scheme of forming large diameter magnesium alloy tube and thick wall magnesium alloy tube was established, and the die structure was designed in detail. Then the DEFORM-3D finite element software is used to simulate the temperature distribution of the extrusion tube, which is of great significance to the study of the hydrostatic extrusion temperature. The hydrostatic extrusion process of large-caliber magnesium alloy tube was simulated and analyzed, and the effects of extrusion ratio on extrusion load, equivalent strain and velocity field were studied. With the increase of extrusion ratio, both the peak pressure and the average pressure of extrusion load will increase, and the effect of extrusion is more obvious than that of peak pressure. The distribution of equivalent strain after tube forming is analyzed. The maximum value of equivalent strain is distributed in the extrusion deformation zone, in which shearing and extrusion deformation mainly occur. Finally, under the 40MN horizontal hydrostatic extrusion press, the preparation of large-caliber magnesium alloy pipe and thick-walled magnesium alloy tube was realized, and the tube was sampled, microstructure analysis and mechanical properties test were carried out. The yield strength and tensile strength of hydrostatic extrusion products were improved obviously, but the elongation of the products was lower. After hydrostatic extrusion, the grain of magnesium alloy tube is elongated along the extrusion direction, sub-grain appears, grain refinement is obvious. The effect of recrystallization annealing process on the properties of hydrostatic extrusion products is also studied, which is of great significance to further improve the plastic properties of products.
【学位授予单位】：南京理工大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：TG379

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