Mg-Sn-Pb镁合金轧制成型机理研究

发布时间：2018-02-11 19:11

本文关键词： 镁合金热加工图轧制织构　出处：《青海大学》2016年硕士论文　论文类型：学位论文

【摘要】：本文采用气体保护搅拌熔炼工艺和金属型铸造法制备了Mg-5Sn-2.5Pb镁合金,并对其高温压缩和热轧变形行为进行了研究。通过热压缩实验,计算了本构关系和建立了热加工图,对Mg-5Sn-2.5Pb镁合金的轧制工艺进行了优化。通过轧制实验,研究了轧制参数对Mg-5Sn-2.5Pb镁合金轧制成型机理的影响。结果表明:Mg-5Sn-2.5Pb镁合金的峰值应力随着变形温度的升高而降低,随着应变速率的增大而增大,这是由于动态回复和动态再结晶的软化作用和加工硬化作用的共同影响。经过计算得到Mg-5Sn-2.5Pb镁合金的表观激活能并确定了适合材料的本构方程,即双曲线函数形式的本构方程。在此基础上,通过计算及线性拟合求出了材料的能量耗散系数和不稳定参数,叠加功率耗散图和流变失稳图得到应变为0.6时的Mg-5Sn-2.5Pb镁合金的热加工图。利用热加工图确定了最佳的可加工区域:材料在变形温度为375°C~450°C、应变速率为0.01s-1~0.3s-1。对Mg-5Sn-2.5Pb镁合金轧制变形后的宏观形貌、机械性能和显微组织进行了观察与分析,确定轧制温度为450°C、轧制速度为20rad/min是Mg-5Sn-2.5Pb镁合金的优化轧制工艺。轧制后镁合金中产生了基面(0002)晶面平行轧制方向的织构。结果表明,轧制温度和轧制速率并不能改变合金的织构类型,却会影响一定的织构强度。
[Abstract]:In this paper, Mg-5Sn-2.5Pb magnesium alloy was prepared by gas shielded agitation melting and metal mold casting. The deformation behavior of high temperature compression and hot rolling was studied. The constitutive relation was calculated and the hot working diagram was established by hot compression experiment. The rolling process of Mg-5Sn-2.5Pb magnesium alloy was optimized. The effect of rolling parameters on the rolling forming mechanism of Mg-5Sn-2.5Pb magnesium alloy was studied. The results showed that the peak stress of the Mg-5Sn-2.5Pb magnesium alloy decreased with the increase of deformation temperature. With the increase of strain rate, the effect of dynamic recovery and dynamic recrystallization on softening and work hardening is considered. The apparent activation energy of Mg-5Sn-2.5Pb magnesium alloy is calculated and the constitutive equation suitable for the material is determined. On the basis of this, the energy dissipation coefficient and the unstable parameters of the material are obtained by calculation and linear fitting. The thermal processing diagram of Mg-5Sn-2.5Pb magnesium alloy with strain 0.6 was obtained by superposing power dissipation diagram and rheological instability diagram. The optimum machinable region was determined by using the hot working diagram: the deformation temperature was 375 掳C ~ (1) 450 掳C, the strain rate was 0.01s ~ (-1) / 0.3s ~ (-1). The Mg-5Sn-2.5Pb magnesium alloy was rolled at a strain rate of 0.01s ~ (-1) / 0.3s ~ (-1). The macroscopic morphologies after deformation, The mechanical properties and microstructure were observed and analyzed. It was determined that the rolling temperature was 450 掳C and the rolling speed was 20 rad-1 / min. The optimized rolling process of Mg-5Sn-2.5Pb magnesium alloy was obtained. After rolling, the texture of the base plane of the magnesium alloy was produced in parallel direction. The results show that the rolling temperature is 450 掳C and the rolling speed is 20 radr / min. Rolling temperature and rolling rate can not change the texture type of the alloy, but will affect the texture strength.
【学位授予单位】：青海大学
【学位级别】：硕士
【学位授予年份】：2016
【分类号】：TG339

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