2A02合金热加工过程微观组织的演化机理研究

Microstructure Evolution Mechanism of 2A02 Aluminum Alloy during Hot Working Process

摘要:

利用热模拟压缩试验，研究了2A02铝合金不同变形条件下的动态软化机制及变形后不同固溶制度下的晶粒演变与微结构演化。结果表明，变形量较低时（变形量为10%、20%与40%）， 2A02铝合金以加工硬化为主，变形量为60%时，加工硬化与动态软化机制交互作用，其中软化机制体现为几何动态再结晶；进一步的光学显微镜与透射电子显微镜观察表明，随着变形量的增加，锯齿状晶界越发明显，在外加应力和热激活的作用下，亚晶通过转动、合并形成大角度晶粒，诱发动态再结晶过程。高温压缩试验后的固溶过程中，固溶时间越长再结晶的等轴晶粒内部位错密度越低，等轴晶粒尺寸随固溶时间的增长而增大。

Abstract:

Grain size and microstructure evolution mechanisms for 2A02 aluminum alloy under different deformation and heat treatment conditions have been investigated by means of hot working simulator and OM and TEM analysis. The results show that when the hot deformation was lower than 40%, work hardening dominated the forging processes. When the hot deformation was up to 60%, work hardening and dynamic softening dominated by geometric dynamic recrystallization (GDRX) interacted and went to a balance, inducing the obvious zigzag type or the serrated grain boundary formed by the movement and merging of sub-grains. During the aging process after the solution treatment, the TEM observation indicates that the dislocation density of equal-axial grains after recrystallization was becoming lower with the increasing of the aging time, while according to the optical microscope results, the longer the aging time was, the larger the obtained equal-axial grains could be.