第二相对铸轧3003铝合金箔坯再结晶行为的影响

Effects of Second Phases on Recrystallization Behavior of Cast-rolled 3003 Aluminum Alloy Foil

目的铸轧法因工艺流程短、生产效率高而被广泛应用于3003铝合金箔板的生产。但铸轧法生产的坯料组织为Mn元素过饱和的固溶体,在后续再结晶退火时易析出细小弥散的第二相,这些第二相会抑制再结晶形核使得合金组织异常粗大,为解决这个问题,需探索最优的热处理工艺。方法采用均匀化退火预处理工艺,在均匀化退火过程中使Mn元素脱溶并析出粗大的第二相,为后续再结晶退火提供形核质点。研究均匀化退火温度对该过程中析出第二相的尺寸和数密度的影响,并研究均匀化退火对再结晶析出行为、形变再结晶晶粒形貌和织构特征的影响。结果经过450、500、550℃均匀化预处理的试样析出了大量粗大的第二相,从而诱发再结晶形核,促使合金组织细化;而原始铸轧样和400℃均匀化预处理的试样在再结晶退火时析出了大量细小的第二相,阻碍再结晶的发生,从而形成粗大的晶粒组织。由于均匀化处理过程中产生粗大粒子诱发形核(PSN)作用,使得500、550、600℃预处理冷轧板退火后具有较弱的再结晶织构。结论在500、550、600℃进行预处理可析出粗大的第二相,促使合金组织细化。通过数学拟合的方法,获得粗大第二相(d>200 nm)数密度与再结晶晶粒平均尺寸之间的关系为d=75.09-30.04ρ+4.08ρ^(2)。

The cast-rolling method is widely used in production of 3003 aluminum alloy foil,because of its short process and high production efficiency.However,the microstructure of as-cast billets is a solid solution supersaturated with Mn,which is easy to precipitate fine and dispersed second phases during subsequent recrystallization annealing.These second phases inhibit recrystallization nucleation and make the alloy microstructure abnormally coarse.The work aims to explore the optimal heat treatment process to solve this problem.The homogenization annealing pretreatment process was used to try to make Mn element exsolution and precipitate second phases during the homogenization annealing process,so as to provide nucleation particles for subsequent recrystallization annealing.The effects of homogenization annealing on recrystallized precipitation behavior,morphology and texture characteristics of deformation recrystallization grains were investigated,especially the effects of homogenization annealing temperature on the size and number density of the second phase precipitated during the process.The results showed that a large amount of coarse second phases were precipitated from the samples homogenized at 450,500 and 550℃,which induced recrystallization nucleation and refined the recrystallization structure.The original sample and the sample homogenized pretreated at 400℃precipitated a quite number of fine second phases during recrystallization annealing,which hindered the recrystallization and resulted in the formation of coarse grain structure.In addition,the sheets pretreated at 500,550 and 600℃had weak recrystallization texture,which thanks to the effect of particle stimulated nucleation(PSN).It is concluded that pretreatment at 500,550 and 600℃can precipitate coarse second phases and promote microstructure refining of the alloy.The relationship between the number density of coarse second phase(d>200 nm)and the average size of recrystallized grain obtained by mathematical fitting method is d=75.09-30.04ρ+4.08ρ2.