退火温度对高纯Al-1% Si-0.5% Cu合金晶粒、异常长大的影响

介绍了在同一变形条件下,退火温度对高纯Al-1%Si-0.5%Cu(质量分数,下同)合金的再结晶晶粒尺寸的影响。实验证明纯度达到99.999%以上的Al-1%Si-0.5%Cu合金锭坯,经过均匀化处理、多向锻造、中间退火及冷轧、再结晶退火后,在420～450℃时即可形成均匀、细小的等轴晶粒,但当退火温度≥480℃时,局部区域出现晶粒异常长大现象,最大晶粒异常长大温度约为480℃。研究认为退火温度较高时,改变了局部区域第二相的溶解析出行为,造成局部区域第二相减少、粗化,所提供的阻力不足以克服晶界移动的驱动力,则在一些晶界阻力不均匀的地方会发生个别晶粒异常长大。因此在该变形条件下,应控制再结晶退火温度低于480℃,在420～450℃时可得到平均晶粒尺寸近50μm的锭坯。

Effect of Annealing Temperature on Abnormal Grain Growth in High Purity of Al-1%Si-0.5% Cu Alloy

The effects of annealing temperature on recrystal grain size under the same condition for high purity of Al-1%Si-0.5%Cu alloy were introduced. It's concluded that the grain size of Al-l%Si-0.5%Cu alloy, which the purity is greater than 99.999%, is fine, and uniform by uniform heat treatment, multi-ram forging, interannealing, cold-rolling, and recrystallization annealing. When the temperature is 420～450 ℃, it can form the equiaxed grain with good uniformity. But when the temperature is over 480 ℃, it appears abnormal grain growth in local areas. On the basis of the observation and analysis, the reasons for abnormal growth of the grain can be concluded. With the annealing temperature lifting, the solution and precipitation of second-phase changes. And it causes reduction and coarsening of the second-phase. It decreases the resistance of grain growth by the second-phase. It can determine that in this deformation condition, the annealing temperature should be controlled below 480 ℃. It can make the grain size below 50 μm with annealing temperature from 420 ℃ to 450 ℃.