AZ80镁合金不同初始状态下的变形组织及性能

Deformation microstructure and properties of AZ80 alloy with different initial status

选取铸态和均匀化态两种不同状态AZ80镁合金作为变形前试样,在温度T=390℃、变形速率ν=2mm·s-1以及应变ε=1.6的条件下进行压缩变形实验,研究了两种不同初始状态对变形组织及性能的影响。结果表明,铸态试样变形后原晶界和枝晶界处粗大β相被压缩破碎且呈流线集中分布,动态再结晶主要发生在晶界和枝晶界附近。均匀化试样经变形后仍残留有原始粗晶,但动态再结晶比例明显高于铸态直接变形;所有试样变形后力学性能均高于初始铸锭,同时由于均匀化变形后晶粒细化比例高,其力学性能优于铸态直接变形。相比铸锭,铸态直接变形伸长率提高不明显,而抗拉强度和硬度分别提高到原来的1.8和1.5倍,因此旨在提高强度和硬度的铸态直接变形是可行的。

In the present work,the as-cast and as-homogenized AZ80 alloys were subjected to the hot compression under the conditions of temperature T=390℃,deformation velocityν=2mm·s-1 and strainε=1.6.The effects of different initial status on deformation microstructure and mechanical properties were investigated.The results show that：1）For the as-cast sample,the original coarseβphase around the dendrite and grain boundaries is broken during the hot compression process,and finally shows a localized distribution of flow lines;Dynamic recrystallization occurs around the grain and dendrite boundaries.For the as-homogenized sample,a small amount of coarse grains still remained after deformation;However,the amount of dynamically recrystallization grains is significantly more than the as-cast deformed sample.2）After deformation,the mechanical properties of samples are both improved,but the mechanical properties of as-homogenized deformed sample are better than those of the as-cast deformed sample because of the high proportion of grain refinement.The tensile strength and hardness of the as-cast deformed sample increase obviously,and are 1.8and 1.5times that of ingot,respectively.Thus,the plastic deformation with the as-cast AZ80 alloy being used as the initial status is feasible for improving the strength and hardness.