7050--T7452鍛件模擬高溫服役環境下組織性能的演化Evolution of microstructure and properties of 7050-T7452 alloy forging simulation in high temperature service environment

通過拉伸試驗和微觀組織觀察等方法對經過不同溫度和時間模擬高溫服役環境熱暴露處理后7050-T7452
鍛件的室溫拉伸性能以及合金金相組織、析出相的變化情況進行系統研究。結果表明：7050-T7452鍛件在 100~175 ℃下熱暴露處理后，合金的強度隨熱暴露溫度的提高和時間的延長而降低，伸長率隨之增加；當熱暴露溫度超過125 ℃后，變化更為明顯；隨熱暴露溫度和時間的變化，合金的晶粒尺寸以及再結晶程度沒有明顯改變；當熱暴露溫度≤125 ℃時，合金晶粒內部析出相的尺寸和種類沒有明顯變化；隨熱暴露時間的增加，晶界無析出帶的寬度略有增寬；當熱暴露溫度超過 125 ℃時，合金晶內的析出相隨溫度以及熱暴露時間的增加而迅速粗化，η相的體積分數增加，晶界無析出帶加寬，合金的強度明顯下降。

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 precipitatefree zones (PFZs) increases a little with the exposed time increasing. When the exposed temperature 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 η phase. The strength of alloy decreases visibly in this period.

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