外浇包熔体温度对7075/6009铝合金铸锭组织和硬度分布的影响

Effect of Melt Temperature in Outside Ladle on Microstructure and Hardness Distribution of 7075/6009 Aluminum Alloy

采用双流浇注连续铸造技术制备了7075/6009铝合金铸件,重点研究了外浇包熔体温度对该复合材料铸锭的组织及铸锭横截面上成分和硬度分布的影响。结果表明:在其他工艺参数一定的情况下,外浇包熔体温度从720℃上升到760℃时,铸锭外层合金的平均厚度减少了14.3%,铸锭内层合金的平均二次枝晶间距由约15μm增加到20μm,铸锭外层合金的平均二次枝晶间距由约80μm增大到100μm,铸件内层合金和外层合金的硬度分别降低了8.5%和9.3%。

The 7075/6009 aluminum ingots were prepared by double-stream-pouring continuous casting. The effect of melt temperature in outside ladle on the microstructure and hardness distribution in the cross section of the ingots was studied. The results show that the average thickness of the outer layer of the composite ingot decreases by 14.3%, the average secondary dendrite arm spacing of the outer layer increases from 15 μm to 20 μm and that of the inner layer increases from 80 μm to 100 μm, the Rockwell hardness of the inner layer and outer layer decreases by 8.5% and 9.3%, respectively, when the melt temperature in outside ladle increases from 720 ℃ to 760 ℃.