7050-T7452锻件模拟高温服役环境下组织性能的演化

Evolution of microstructure and properties of 7050-T7452 alloy forging simulation in high temperature service environment

通过拉伸试验和微观组织观察等方法对经过不同温度和时间模拟高温服役环境热暴露处理后7050-T7452锻件的室温拉伸性能以及合金金相组织、析出相的变化情况进行系统研究。结果表明：7050-T7452锻件在100-175℃下热暴露处理后，合金的强度随热暴露温度的提高和时间的延长而降低，伸长率随之增加；当热暴露温度超过125℃后，变化更为明显；随热暴露温度和时间的变化，合金的晶粒尺寸以及再结晶程度没有明显改变；当热暴露温度≤125℃时，合金晶粒内部析出相的尺寸和种类没有明显变化；随热暴露时间的增加，晶界无析出带的宽度略有增宽；当热暴露温度超过125℃时，合金晶内的析出相随温度以及热暴露时间的增加而迅速粗化，卵相的体积分数增加，晶界无析出带加宽，合金的强度明显下降。

The evolution of microstructure and properties of 7050-T7452 alloy forging simulation in high temperature service environment for different times and temperatures was studied by tensile test and transmission electron microscopy. The results show that the strength of 7050-T7452 alloy forging decreases with the thermal exposed time and temperature increasing in the range of 100-175 ℃, however, the elongation increases. The change of strength is obvious when the exposed temperature is higher than 125 ℃, and the change of grain size and recrystallization is not obvious. When the exposed temperature is lower than 125 ℃, the sizes and species of precipitates do not change obviously. The width of precipitate-free zones （PFZs） increases a little with the exposed time increasing. When the exposed temperaatre is higher than 125 ℃, the precipitates in matrix are coarser with the exposed temperature and time increasing. Meanwhile, the precipitate size and width of PFZs increase obviously, and the dominant precipitate is t/phase. The strength of alloy decreases visibly in this period.