冷轧不同微量化学状态Al-Mn-Fe-Si铝合金的等温退火

通过3种不同热处理工艺使一种Al-Mn-Fe-Si合金获得了不同固溶液和不同尺寸及数量的弥散析出相,包括铸造态,一种富含高密度、细小、弥散相的状态,另外一种状态则仅有少量、相对粗大的弥散相。采用EBSD技术系统研究冷轧后退火过程中微观组织的演变以及初始组织状态对再结晶动力学、再结晶晶粒形貌和织构的影响。结果表明,再结晶动力学、最终微观组织和织构由加工条件和合金的初始组织和固溶度决定。高密度弥散析出相阻止形核,显著阻碍软化过程,最终得到粗大的狭长晶粒以及P和ND-rotated cube织构。在没有预先存在的细小、稠密的弥散相并且在退火过程中弥散相析出数量很少的时候则能更快完成再结晶并得到均匀、细小的等轴晶以及显著的立方织构。

Isothermal annealing of cold-rolled Al-Mn-Fe-Si alloy with different microchemistry states

Microstructural evolution of a cold-rolled Al-Mn-Fe-Si alloy during annealing was studied. Except the as-cast variant, two other different homogenizations were considered, one gave a high density of fine dispersiods providing a considerable Zener drag influencing the softening behavior while the other gave a lower density of coarser dispersoid structure providing a much smaller drag effect. The gradual microstructural evolutions during annealing for the three variants were captured by interrupting annealing at different time. Effects of microchemistry state on recrystallization kinetics, recrystallized grain structure and texture were characterized by EBSD. It is demonstrated that the actual softening kinetics, final microstructure and texture are a result of delicate balance between processing condition and microchemistry state. Strong concurrent precipitation takes place in the case with high concentration of Mn in solid solution, which suppresses nucleation and retards recrystallization and finally leads to grain structure of coarse elongated grains dominated by a P texture component together with a ND-rotated cube component. On the contrary, when solute content of Mn is low and pre-existing dispersoids are relatively coarser, faster recrystallization kinetics is exhibited together with an equiaxed grain structure with mainly cube texture.