AA7005铝合金的热加工变形特性

研究了AA7005合金高温压缩变形时的流变应力、动态回复与再结晶以变形组织变化特征。合金稳态变形时,应变速度、温度和流变应力之间满足包含热激活材料常数的Arrhenius项的双曲正弦关系,变形过程为受位错增殖和相互销毁速率控制的热激活过程,螺型位错的交滑移和刃型位错的攀移为主要动态回复机制。动态回复时,形成典型的变形亚晶组织,亚晶尺寸随1nZ的减小而增大。高温低速变形条件下,合金发生局部几何动态再结晶,流变曲线呈现连续下降的特征,形成与原始纤维组织不同的细小等轴大角度再结晶晶粒。

Hot deformation behaviors of AA7005 aluminium alloy

The flow behavior and dynamic recovery and recrystallization, as well as microstructure evolution, of AA7005 aluminium alloy in hot compression were investigated. A hyperbolic sine relationship can satisfactorily correlate temperature and strain rate with flow stress through an Arrhenius term that involves thermal activation parameters during steady state deformation of the alloy. The hot deformation for the alloy is a thermally activated process, which is governed by rate controlling mechanisms of dislocations. The main dynamic recovery mechanisms of the alloy are proposed to be cross slip of jogged screw dislocations and climb of edge dislocations. Typical subgrain structures are highly developed when the alloy is softened by dynamic recovery. The mean size of the subgrains increases with decrease of the natural logarithm of Zener Hollomon parameter. Local geometric dynamic recrystallization is activated when the alloy is compressed at higher temperatures and lower strain rates, while the flow curves decrease gradually with increase of true strain. Fine eqiaxial recrystallized grains with large angle grain boundaries, which are different from the original elongated grains, developed resultantly.