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提出一种新型的镁合金复合挤压方法,将传统的挤压和大塑性变形方法等通道挤压相结合,也就是将压缩变径挤压和剪切(一次或者连续二次)相结合(简称ES)。根据ES变形的思想,设计并制造了适合热模拟仪Gleeble1500D的ES挤压装置,进行了不同温度下的AZ31镁合金ES挤压测试,观察了ES挤压所得到的AZ31镁合金挤压棒的微观组织。结果表明:当挤压比为4时,ES挤压的累计应变为2.44,可得到平均尺寸为2μm的微观组织。动态再结晶的发生是ES挤压产生晶粒细化的主要原因。根据ES热模拟挤压过程的应力—应变曲线和挤压力曲线的特点,ES热模拟实验中镁合金发生了与一般动态再结晶过程不一样的再结晶过程,具有明显的两个动态再结晶阶段,被称为“双级动态再结晶”。基于热模拟的ES挤压证明了ES挤压是可行的。生产实践结果表明,不同条件下的工业ES挤压可大批量生产镁合金挤压棒材。
A new type of magnesium alloy compound extrusion method is proposed, which combines traditional extrusion and channel plastic deformation methods such as compression-reduction extrusion and shearing (once or twice consecutively) Referred to as ES). According to the idea of ES deformation, an ES extrusion device suitable for the Gleeble 1500D thermal simulator was designed and manufactured. The ES31 extrusion test of AZ31 magnesium alloy at different temperatures was carried out. The ES31 extruded magnesium alloy extrusion rod microstructure. The results show that when the extrusion ratio is 4, the total strain of ES extrusion is 2.44, and the microstructure with the average size of 2μm can be obtained. The occurrence of dynamic recrystallization is the main reason for grain refinement caused by ES extrusion. According to the characteristics of the stress-strain curve and extrusion pressure curve of the ES thermal simulation extrusion process, the recrystallization process of the magnesium alloy in the ES thermal simulation experiment is different from that of the general dynamic recrystallization process and has obvious two dynamic recrystallization Phase, known as “two-stage dynamic recrystallization ”. ES extrusion based on thermal simulation proves that ES extrusion is feasible. Production practice results show that under different conditions of industrial ES extrusion mass production of magnesium alloy extruded bars.