【作者】 王荣；

【导师】 董杰； 张平；

【作者基本信息】 上海交通大学 ， 材料加工工程， 2009， 硕士

【摘要】 镁合金板带材在航空、航天、汽车和国防工业中有巨大的应用前景。但由于镁合金室温塑性变形能力差,轧制过程中板材易产生裂纹,生产效率不高,导致镁合金板带材价格昂贵,已成为镁合金板材广泛应用的一个瓶颈。本文研究了AZ31和Mg-12Gd-3Y-0.4Zr(GW123K)合金板材的轧制工艺及组织性能的演变规律,旨在为镁合金板材的工业化应用提供借鉴。挤压态AZ31合金的轧制成形试验表明,合金在高于300℃时具有良好的轧制成形能力。组织性能研究结果表明,晶粒随轧制温度的升高而增大。相同的变形温度下,组织随道次压下量的增大而细小,但道次压下量的大小对板材的力学性能无显著影响。400℃下以30%～40%的道次压下量进行轧制可用于进行小批量AZ31板材的生产。为了解决板材在轧制过程中的边裂问题,本文设计了内加热式轧辊,对铸态AZ31板材进行了等温轧制,发现提高轧辊温度有利于改善板材的表面质量及连续轧制性能。挤压态GW123K合金板材的轧制试验表明,此合金在450℃下变形能力良好,可实现最大70%的道次压下量。总变形量相同的情况下,道次压下量越大,轧制板材的晶粒越细小,织构分布的散漫度越大,综合力学性能越优。450℃、50%压下量轧制的板材组织及力学性能最优,屈服强度323MPa、抗拉强度396MPa,延伸率10.4%。轧制态合金中存在两种第二相:方块相和石头状相。轧制后T5态的组织性能研究表明,峰时效时合金中的析出相为β’亚稳相,该相使合金的强度显著提高,最佳室温力学性能为屈服强度396MPa,抗拉强度486MPa,延伸率2.9%。细晶强化、第二相强化和加工硬化是变形态GW123K合金的主要强化机制。更多还原

【Abstract】 Light magnesium alloy sheets are widely required in aerospace, automotive, and military industries. Due to their poor plastic deformability at room temperature, magnesium alloy sheets tend to crack during rolling process, resulting in a lower productivity, higher price of magnesium sheets, and greatly restricted the use of magnesium alloys. So in this paper, rolling process, microstructural evolution and mechanical properties of AZ31 and Mg-12Gd-3Y-0.4Zr (GW123K) alloys were investigated, in order to give an example for the coming industrialization of the magnesium alloy sheets in future.The experimental results showed that AZ31 alloy has good millability under the condition of deformation temperature larger than 300℃. The grain size is increased with the rise of rolling temperature,while decreased with the increase of rolling reduction. The rolling reduction hasn’t remarkable effect on mechanical properties of AZ31 Mg alloy sheets. The rolling temperature of 400℃and the reduction in thickness per pass of 30～40% can be applied for small-lot production of magnesium alloy sheets.Electric heated rollers were designed to solve the problem of edge cracking in rolling process. Isothermal rolling were performed on as-cast AZ31 alloy, the results show that heated roller can improve continues millability and the surface quality of the rolled sheets.The rolling experiment of extruded GW123K alloy shows that this alloy has good deformability at 450℃, and the maximum reduction can reached 70% per pass by using heated rollers. As the growth of reduction, the grain size becomes finer, the texture becomes more randomized, and the mechanical property becomes better. Rolled under 450℃with the reduction of 50% per pass can achieved the best properties, the ultimate tensile is 396MPa, yield strength is 323MP, and elongation is 10.4%. Stone-shaped compound and cuboid-shaped compound exist in the rolled alloys as second phases.Participates of GW123K alloy at peak-aged condition isβ’, which acts as the key contributor to the high strength. The highest strength of GW123K at T5 condition shows ultimate tensile strength=486MPa, yield strength=396MPa, corresponding elongation=2.9%.更多还原