离心铸造与轧制制备AZ91镁合金板材成型工艺研究
发布时间：2018-11-09 17:49
【摘要】：镁合金作为最轻的金属结构材料,广泛应用于汽车、航空航天及3C等领域,而镁合金产品主要通过板材的形式使用。因此研制与开发短流程、大宽幅、高性能镁合金板材受到人们广泛关注。本文通过离心铸造数值模拟与浇注,固溶处理,板材轧制及板材的退火处理,确定了一套合理的AZ91镁合金板材成型工艺,研究过程如下:(1)通过计算机对离心铸造制备长度为1500mm,外直径为400mm,厚度为20mm的AZ91镁合金管材的浇注过程进行流场及温度场的模拟,分析得出:离心铸造浇注过程中,合金液由浇口流入模具并向两端流动,逐层充型,当浇注时间至8.4s时,第一层合金液首次充满模具,20s时浇注过程结束;浇注过程中浇口部位合金液温度最高,远离浇口方向温度逐渐降低,浇注结束时,管材两端完全凝固,管材中心部位尚未凝固。(2)通过离心铸造制备长度为1500mm,外直径为400mm,厚度为20mm的AZ91镁合金管材并确定离心铸造工艺参数为:离心转速900r/min,浇注温度700℃,模具预热温度200℃;离心铸造制备AZ91镁合金管材外表面光滑平整,厚度均匀,充型完整,管材力学性能较铸态有明显提高,抗拉强度为158MPa,伸长率为3.4%。管材晶粒细小,分布均匀。(3)对离心铸造AZ91镁合金管材进行固溶处理,通过实验分析得出:管材力学性能随着固溶温度的升高而提高,固溶温度为415℃时力学性能达到最好,抗拉强度为176MPa,伸长率为6.7%;管材抗拉强度随着固溶时间的增加先升高后下降,固溶时间为18h时达到最好,抗拉强度为181MPa,伸长率随固溶时间的增长而升高,固溶时间为24h时达到最好,伸长率为9.2%,随着固溶时间的增加,β-Mg17Al12相溶于基体能力增强。(4)对离心铸造AZ91镁合金管材进行展平,包套轧制。通过不同轧制温度下板材对比可知:轧制温度为400℃时,板材外形无明显表面裂纹及边部开裂,厚度均匀,抗拉强度及伸长率较铸态得到明显提高,板材伸长率及抗拉强度分别为7.2%和291MPa,轧制后板材组织均明显细化,轧制过程中发生动态再结晶;通过不同轧制总压下量板材对比发现:大压下量板材力学性能得到明显提高,其抗拉强度及伸长率分别为317MPa和7.4%;对轧制态板材进行不同保温时间的退火处理发现:退火后板材塑性提高,保温时间90min时达到最好,伸长率分别为8.6%。
[Abstract]:As the lightest metal structure material, magnesium alloy is widely used in automotive, aerospace and 3C fields, while magnesium alloy products are mainly used in the form of sheet metal. Therefore, the research and development of magnesium alloy sheet with short process, wide width and high performance has received extensive attention. Through centrifugal casting numerical simulation and casting, solid solution treatment, plate rolling and sheet annealing treatment, a set of reasonable forming process of AZ91 magnesium alloy sheet was determined. The research process is as follows: (1) the flow field and temperature field of AZ91 magnesium alloy pipes with a length of 1500 mm, an outer diameter of 400 mm and a thickness of 20mm are simulated by computer, and the results show that: in the process of centrifugal casting, When the pouring time reaches 8.4 s, the first layer of alloy liquid fills the mold for the first time, and the pouring process ends at 20 s. During the pouring process, the temperature of the alloy liquid was the highest in the gate part, and gradually decreased away from the gate. At the end of pouring, the two ends of the pipe were completely solidified, and the central part of the pipe was not solidified. (2) the length of the tube was 1500mm by centrifugal casting. The outer diameter is 400mm and the thickness of AZ91 magnesium alloy pipe is 20mm. The technological parameters of centrifugal casting are determined as follows: centrifugal rotational speed 900rr / min, pouring temperature 700 鈩，
本文编号：2321129
[Abstract]:As the lightest metal structure material, magnesium alloy is widely used in automotive, aerospace and 3C fields, while magnesium alloy products are mainly used in the form of sheet metal. Therefore, the research and development of magnesium alloy sheet with short process, wide width and high performance has received extensive attention. Through centrifugal casting numerical simulation and casting, solid solution treatment, plate rolling and sheet annealing treatment, a set of reasonable forming process of AZ91 magnesium alloy sheet was determined. The research process is as follows: (1) the flow field and temperature field of AZ91 magnesium alloy pipes with a length of 1500 mm, an outer diameter of 400 mm and a thickness of 20mm are simulated by computer, and the results show that: in the process of centrifugal casting, When the pouring time reaches 8.4 s, the first layer of alloy liquid fills the mold for the first time, and the pouring process ends at 20 s. During the pouring process, the temperature of the alloy liquid was the highest in the gate part, and gradually decreased away from the gate. At the end of pouring, the two ends of the pipe were completely solidified, and the central part of the pipe was not solidified. (2) the length of the tube was 1500mm by centrifugal casting. The outer diameter is 400mm and the thickness of AZ91 magnesium alloy pipe is 20mm. The technological parameters of centrifugal casting are determined as follows: centrifugal rotational speed 900rr / min, pouring temperature 700 鈩，
本文编号：2321129
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