均匀化退火对7A04铝合金挤压材显微组织的影响  

Effect of Homogenization Annealing on Microstructure of Extruded 7A04 Aluminum Alloy

作　　者：薛杰 李保永[1] 秦中环 Xue Jie;Li Baoyong;Qin Zhonghuan(Beijing Hangxing Machinery Co.,Ltd.,Beijing 100013)

机构地区：[1]北京航星机器制造有限公司,北京100013

出　　处：《航天制造技术》2018年第6期11-16,共6页Aerospace Manufacturing Technology

基　　金：航天飞航弹体及发射装备轻量化柔性制造成套设备应用示范(2018ZX04014-001)资助

摘　　要：利用OM、SEM、TEM、EBSD等手段研究了均匀化退火冷却方式对7A04铝合金挤压材显微组织的影响。结果表明,7A04铝合金均匀化退火的冷却方式对基体上的第二相种类和分布特征影响显著。均匀化退火水冷、油冷、空冷坯料的第二相数量较少,炉冷的坯料第二相较多,由少量粗大的Al_2CuMg、Al_7Cu_2Fe和大量弥散分布的针状MgZn_2相组成,同时随着均匀化冷却速率的降低,粗大第二相的含量先增加后降低,其中炉冷至250℃空冷时,第二相含量达到最大值,约为17.5%。粗大第二相较多坯料在后续热挤压时,粗大第二相作为再结晶形核位置,促进动态再结晶;又由于析出的细小析出相钉扎晶界,阻碍再结晶晶粒的长大。因此,炉冷坯料挤压后固溶时效的挤压材比水冷坯料挤压材晶粒尺寸显著减小。The effect of homogenizing annealing cooling on the microstructure of extruded 7A04 aluminium alloy is researched through OM,SEM,TEM,EBSD and so on.The results show that,the cooling method of 7A04 aluminum alloy homogenizing annealing has a significant effect on the type and distribution characteristics of the second phase on the matrix.The number of the second phase in the furnace-cooled billets after homogenization annealing is more than that of the second phase in the water-cooled,oil-cooled and air-cooled billets,which consists of a small amount of coarse Al2CuMg,Al7Cu2Fe and a large amount of dispersed needle-shaped MgZn2 phases.At the same time,with the decrease of homogenization cooling rate,the content of the coarse second phase first increases and then decreases.When the temperature of furnace is cooled to 250℃ and then air cooling,the content of second phases reaches the maximum value, about 17.5%.During subsequent hot extrusion,the coarse second phase acts as the recrystallization nucleation position to promote dynamic recrystallization,and the fine precipitated phase pins the grain boundary,which hinders the growth of recrystallized grains.Therefore,the grain size of extrusion after solution ageing is significantly smaller than that of water-cooled extrusion.

关 键 词：均匀化退火 Al—Zn—Mg—Cu合金 热挤压 显微组织 

分 类 号：TG379[金属学及工艺—金属压力加工] TG166.3