新聞資訊
回歸再時效對7050鋁合金強度和斷裂韌性的影響
發布人：上海艾荔艾金屬材料有限公司www.jshcn.cn
更新時間：2015-10-17
采用光學顯微鏡、掃描電鏡、透射電鏡、常溫拉伸及斷裂韌性實驗研究回歸溫度及回歸時間對7050鋁合金力學性能和斷裂韌性的影響。
回歸再時效對7050鋁合金強度和斷裂韌性的影響Effects of retrogression and reaging on strength and fracture toughness of aluminum alloy 7050
采用光學顯微鏡、掃描電鏡、透射電鏡、常溫拉伸及斷裂韌性實驗研究回歸溫度及回歸時間對7050鋁合金力學性能和斷裂韌性的影響。結果表明：回歸過程中，一部分GP區回溶進入基體，另一部分長大轉變為η′相，同時η′相轉變為η相，η相則不斷粗化。隨著回歸時間的延長，合金的強度先下降至一谷值然后上升至一峰值再單調下降；再時效態合金強度先增大后減小，再時效態合金強度大于對應回歸態合金強度。在190 ℃回歸時，回歸及再時效7050合金(RRA)的斷裂韌性均隨回歸時間的延長而不斷增大；然而，在170和150 ℃回歸時，回歸及再時效7050合金的斷裂韌性先增大至一峰值然后下降至一谷值再增大。回歸態合金的斷裂韌性大于對應再時效態合金的斷裂韌性。隨著回歸時間的延長，合金的斷裂模式由沿晶斷裂向穿晶韌窩斷裂過渡。
The effects of retrogression and reaging (RRA) on the tensile property and fracture toughness of aluminum alloy 7050 were investigated by optical microscopy, scanning electron microscopy, transmission electron microscopy, tensile and toughness tests. The results show that during the retrogression treating, one part of GP zone dissolves into Al matrix and the other grows, and then transforms into η′ phase. At the same time, the η′ phase transforms into η phase constantly. And the η phase becomes coarse gradually. With the retrogression time elongating, the strength of the alloy falls to a valley value before increasing to a peak value, and then monotonically decreases. Meanwhile, the strength of the reaged alloys first increases and then decreases. The strength of the reaged alloys is larger than that of the retrogressed alloys. With the retrogression time elongating, the fracture toughness of alloy 7050 RRA retrogressed at 190 ℃ increases. However, the fracture toughness of alloy 7050 RRA retrogressed at 170 ℃ and 150 ℃ increases to a peak value before decreasing to a valley value and then increases. The fracture toughness of the retrogressed alloys is larger than that of the reaged alloys. With the retrogression time elongating, the main fracture mechanism changes from the intergranular fracture to transgranular fracture.
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