【摘要】 将AZ91D镁合金铸锭在330℃往复挤压4道次后,在300℃连续正挤压制成φ5mm的丝材,用OM,SEM分析不同方式挤压前后组织的变化,研究往复挤压及随后正挤压对其组织与性能的影响。研究表明,AZ91D镁合金往复挤压4道次及连续正挤压制备的φ5mm丝材组织均为等轴晶,晶粒尺寸分别为小于10μm及1μm~3μm。经往复挤压及随后的正挤压,AZ91D铸造镁合金的综合力学性能均可得到显著提高,其主要原因是基体组织α-Mg和强化相β-Mg17Al12的细化。往复挤压4道次后,材料真应变高达20.36,正挤压过程中等效应变速率达到0.192s-1,AZ91D镁合金往复挤压及正挤压晶粒的细化机制主要包括破碎、动态再结晶和动态回复。更多还原

【Abstract】 A reciprocating-extrusion (RE) process was used to work the AZ91D (Mg-9Al-1Zn, wt%) magnesium alloys cast ingot at 330 ℃ for 4 passes, and then, continuing-forward-extrusion process was done for producing φ 5 mm wire materials at 300 ℃ . The micros-tructures and mechanical properties of AZ91D alloy were investigated by OM and SEM at each processing step. The results showed that the AZ91D alloy reciprocating-extruded for 4 passes had equiaxed grains with less than 10 μm, and the φ 5 mm wire material had also equiaxed grains with smaller size of only 1 μm~3 μm. The general mechanical properties (the yield strength and ultimate tensile strength and elongation and Vickers-hardness) of AZ91D alloy both reciprocating-extruded and continuing-forward-extruded were improved significantly, which was mainly attributed to the refinement of α-Mg matrix and strengthening β-Mg17Al12 phase. After the RE 4 passes, the true strain of the alloy was up to 20.36, the equivalent strain rate during continuing forward extrusion was 0.192 s-1. So the proposed refining mechanisms of the reciprocating-extruded and continuously forward-extruded wire materials of A191D alloy involved fragmentation, dynamic recrystallization and repeated mass flow.更多还原