Effect of low-temperature retrogression and re-aging treatment on the microstructure and properties of 7B04-T651 Al alloy thick plates
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摘要: 研究了回歸及回歸再時效處理對7B04鋁合金預拉伸厚板的顯微組織、力學性能及電導率的影響.通過透射電子顯微鏡(TEM)觀察了回歸再時效合金的微觀組織,并對合金進行了力學性能及電導率測試.結果表明:采用合適的回歸再時效工藝(180℃/1h,水淬+120℃/22h)可使材料具有接近T6態合金強度的同時,電導率大幅度提升,達21.0MS·m-1;此時,合金晶內組織與T6狀態相似,析出相細小呈彌散分布,而晶界組織與雙級T74時效組織特征相似,晶界析出相粗大呈不連續分布,晶界兩側伴之以明顯的晶界無析出帶.Abstract: 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.
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