淬火冷却方式及宏观取向对Al-Zn-Mg-Cu合金力学性能的影响

Effects of quenching cooling method and macroorientation on mechanical properties of Al-Zn-Mg-Cu alloys

以7050铝合金为研究对象,研究热处理状态(空冷时效与水冷时效)和宏观取向(与轧制方向成0°,45°,90°)耦合作用对合金力学性能的影响。结果表明:水冷时效态的样品中析出相细小均匀弥散,晶界无析出带较窄。在空冷时效态下,过饱和的溶质不仅会以半共格的Al3Zr为核心形成粗大析出相,还会沿位错大量析出。此外,与水冷时效态相比,空冷时效态晶界相尺寸大幅增加,晶界无析出带显著宽化,不同宏观取向样品的强度和伸长率都明显下降。宏观取向对两种状态样品强度的差值影响较小,但对伸长率的差值影响较大。当拉伸方向与轧制方向成45°方向时,空冷诱导的伸长率下降幅度最小;当拉伸方向与轧制方向成90°时,下降幅度最大。

The 7050 aluminum alloy was studied as the research object to investigate the coupling effect of heat treatment state(air quenching aging and water quenching aging)and macroscopic orientation(0°,45°,and 90°concerning the rolling direction)on mechanical properties of the alloy.The results indicate that the precipitated phases in the water-cooled aged samples are small,uniformly dispersed,and the grain boundaries have narrow precipitate free bands.In the air-cooled aging state,the supersaturated solutes not only form coarse precipitates with semi coherent Al3Zr as the core,but also precipitate a large amount along dislocations.In addition,compared with the water-cooled aging state,the grain boundary phase size in the air-cooled aging state increases significantly,and the precipitate free zone at the grain boundary widens significantly.The strength and elongation of samples with different macroscopic orientations are significantly reduced.The influence of macroscopic orientation on the difference in strength between two states of samples is relatively minimal,but it has a significant impact on the difference in elongation.When the tensile direction is at 45°to the rolling direction,the decrease in elongation induced by air cooling is the slightest,while the tensile direction is at 90°to the rolling direction,the maximum decrease is observed.