低温回归再时效对7B04-T651铝合金厚板组织与性能的影响

研究了回归及回归再时效处理对7B04铝合金预拉伸厚板的显微组织、力学性能及电导率的影响.通过透射电子显微镜(TEM)观察了回归再时效合金的微观组织,并对合金进行了力学性能及电导率测试.结果表明:采用合适的回归再时效工艺(180℃/1h,水淬+120℃/22h)可使材料具有接近T6态合金强度的同时,电导率大幅度提升,达21.0MS·m^-1;此时,合金晶内组织与T6状态相似,析出相细小呈弥散分布,而晶界组织与双级T74时效组织特征相似,晶界析出相粗大呈不连续分布,晶界两侧伴之以明显的晶界无析出带.

Effect of low-temperature retrogression and re-aging treatment on the microstructure and properties of 7B04-T651 Al alloy thick plates

The microstructure and properties of retrogression and retrogression re-aging (RRA) treated 7B04-T651 Al alloy prestretched thick plates were studied by transmission electron microscopy, MTS-810 test system and conductivity meter. The results show that the appropriate RRA temper with retrogression at 180± 5℃ for 1 -2h can produce the remarkable improvement in electrical conductivity, with only a 2%-5% reduction in strength below T6. TEM observations of RRA samples show that the precipitation is extremely fine and distributed homogeneously inside the grains, being slightly denser and more stable than that resulting from the T6 temper; whilst the grain boundary precipitation is quite different from that resulting from T6 treatment, the particles being coarser, and much closer to the precipitation resulting from T74 temper.