热加工对铸造AM50镁合金显微结构和力学性能的影响

Effect of Equal-Channel Angular Pressing on Microstructure and Mechanical Properties of AM50 Magnesium Alloy

采用锻造和等通道转角挤压(ECAP)等技术研究了热加工对铸造AM50镁合金显微结构和力学性能的影响,以改善该合金的力学性能。结果发现,ECAP对铸造AM50镁合金和锻造AM50镁合金两种显微结构的影响不同,这是由于两种状态初始晶粒尺寸不同引起的。铸态AM50镁合金晶粒尺寸粗大,经过ECAP工艺后,晶界上出现大量平直滑移线;而锻态AM50镁合金经过ECAP工艺后,晶粒进一步细化,滑移线痕迹不明显。铸态AM50镁合金经过ECAP工艺后显微硬度从54.5提高到72.3,锻造AM50镁合金经过ECAP工艺后显微硬度从60.3提高到81.9。铸造AM50镁合金经过锻造及ECAP工艺热加工后力学性能抗拉强度提高到320 MPa,同时延伸率保持在35%以上。

Forging and equal-channel angular pressing （ECAP） technology were applied to investigate the effect of heat machining process on microstructures and mechanical properties of die cast AM50 magnesium alloy. It is found that the effects of ECAP on the cast AMSO magnesium alloy and forged AM50 magnesium alloy are different, due to their different size of grains. For the cast AMSO magnesium alloy, the original size of grains is coarse, and plenty of straight slipping lines form at grain boundaries after ECAP; but for the forged AM50 magnesium alloy, after ECAP, the size of grains is refined and no obvious slipping lines are found. After ECAP, the micro-hardness of cast AM50 magnesium alloy increases from 54.5 to 72.3, and the micro-hardness of forged AM50 magnesium alloy increases from 60.3 to 81.9. The tensile strength of cast AM50 magnesium alloy increases to 320 MPa, with the elongation of more than 35% after forging and ECAP process.