AlMnFeSi合金退火过程中的微观组织及力学性能的演变

摘要

An Al-Mn-Fe-Si model alloy was subjected to two homogenization treatments,to achieve materials with different levels of Mn in solid solution and dispersoid densities,followed by cold rolling and back-annealing.Characterization of homogenization and deformation structures with respect to the effect of different microchemistries and strains on the structures was performed.Time-temperature-transformation (TTT) diagram with respect to precipitation and recrystallisation as a basis for analysis of the degree of concurrent precipitation was established.The TTT-diagram shows a strong effect of Mn concentration in solid solution and dispersoid density on the softening behavior.Recrystallization which finishes without the effect of concurrent precipitation results in an even,fine and equiaxed grain structure.Precipitation prior to or during recrystallization (concurrent) does retard the softening kinetics and leads to a coarse grain structure.However,the effect also depends on the duration of recrystallization and amount of precipitation.Recrystallization proceeding over a long time combined with a large amount of concurrent precipitation has a strong effect,otherwise the effect will be limited.Pre-existing fine and dense dispersoids (mean size 0.1 μm) before back-annealing do also lead to a coarse grain structure after recrystallization no matter whether additional concurrent precipitation occurs.%通过2种不同的均匀化热处理及随后的冷轧,使一种3xxx系模型合金获得不同尺寸和分布的弥散析出相,并使铝基体含有不同含量的Mn.系统研究不同均匀化热处理组织和冷轧变形量对退火过程中模型合金的回复与再结晶行为的影响.根据实验结果,绘制出弥散析出相和再结晶过程的相互作用时间-温度-转变曲线(TTT).TTT曲线显示固溶体中Mn的含量和弥散析出相的颗粒密度对软化行为有强烈的影响.在再结晶退火过程中或再结晶退火之前析出的高密度、细小、弥散析出相显著阻碍软化过程,并形成粗大的再结晶组织.在没有细小、稠密的弥散相影响下的再结晶退火,可以获得均匀、细小的等轴晶.而且,弥散析出相对再结晶过程的阻碍作用取决于再结晶过程的持续时间和弥散析出相的数量.在持续时间长的再结晶过程中,细小、稠密的弥散相对再结晶有着强烈的影响,而在其他情况下影响则有限.不管再结晶过程中是否受到弥散相析出的影响,在再结晶退火之前已经存在于组织中的细小、稠密的弥散相(平均尺寸0.1 μm)也会导致再结晶退火之后形成粗大的再结晶组织.