本文選題：靜液擠壓 + 數(shù)值模擬��； 參考：《南京理工大學》2017年碩士論文

【摘要】：本文對AZ80鎂合金超高壓靜液擠壓成形工藝進行研究。首先對超高壓靜液擠壓系統(tǒng)進行了總體方案設(shè)計,制定了超高壓靜液擠壓的工藝流程,對關(guān)鍵工藝參數(shù)和靜液擠壓原理開展深入理論研究。制定了大口徑鎂合金管材和厚壁鎂合金管材成形的工藝方案,并對模具進行了詳細結(jié)構(gòu)設(shè)計。然后采用DEFORM-3D有限元軟件對超高壓靜液擠壓進行了數(shù)值模擬,得到了擠壓筒溫度場的分布規(guī)律,這對靜液擠壓溫度的研究具有指導(dǎo)意義。對大口徑鎂合金管材的靜液擠壓成形過程進行了仿真分析,研究了擠壓比對擠壓載荷、等效應(yīng)變和速度場的影響。隨著擠壓比增大,擠壓載荷的峰值壓力和平均壓力都會隨之增大,擠壓比對峰值壓力的影響更明顯。分析了管材成形后的等效應(yīng)變的分布,等效應(yīng)變的最大值分布在擠壓變形區(qū),材料在該區(qū)域主要發(fā)生剪切和擠壓變形。最后,在40MN臥式靜液擠壓機下,實現(xiàn)大口徑鎂合金管材和厚壁鎂合金管材的制備,并對管材取樣,進行顯微組織分析和力學性能測試。靜液擠壓制品的屈服強度和抗拉強度得到明顯提高,但制品延伸率較低。靜液擠壓后的鎂合金管材組織,其晶粒沿擠壓方向被拉長,出現(xiàn)亞晶粒,晶粒細化明顯。本文還研究了再結(jié)晶退火工藝對靜液擠壓制品性能的影響,這對于進一步改善制品塑性性能具有重要意義。
[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.
【學位授予單位】：南京理工大學
【學位級別】：碩士
【學位授予年份】：2017
【分類號】：TG379

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