【摘要】：本文研究熱處理工藝對Al-5.8Zn-2.7Mg-1.6Cu鋁合金的應力腐蝕性能的影響。采用光學顯微鏡、電子掃描顯微鏡研究鋁合金的顯微組織與相組成,通過拉伸實驗測試鋁合金的力學性能,運用慢應變速率拉伸試驗來研究鋁合金的抗應力腐蝕性能,同時還測試了鋁合金的硬度、電導率。通過分析實驗結果,得出了可以使Al-5.8Zn-2.7Mg-1.6Cu鋁合金獲得力學性能與抗應力腐蝕性能較佳的熱處理工藝。主要結論如下:(1)探究了高溫預析出對Al-5.8Zn-2.7Mg-1.6Cu鋁合金抗應力腐蝕性能的影響規(guī)律。高溫預析出可以改變晶內和晶界析出相的大小及其分布狀態(tài),能夠抑制陽極溶解和抑制氫脆,從而提高合金的力學性能和抗應力腐蝕性能。經420°C預析出溫度處理后,合金的應力腐蝕敏感性最低,抗應力腐蝕性能增強,但其強度和硬度會有所降低。Al-5.8Zn-2.7Mg-1.6Cu鋁合金獲得較佳抗應力腐蝕性能的高溫預析出工藝為470℃×1h+420℃×0.5h。(2)探究了雙級固溶對Al-5.8Zn-2.7Mg-1.6Cu鋁合金抗應力腐蝕性能的影響規(guī)律。雙級固溶中一級固溶時間和二級固溶時間是影響Al-5.8Zn-2.7Mg-1.6Cu鋁合金性能的最主要因素。雙級固溶的目的一是為了在一級固溶階段發(fā)生回復,消耗變形儲能,降低再結晶驅動力;二是為了讓結晶相按照一定順序溶入基體中,提高固溶溫度,充分溶解第二相。通過正交試驗結果得出:Al-5.8Zn-2.7Mg-1.6Cu鋁合金獲得較佳的抗拉強度的雙級固溶工藝為440℃×90min+470℃×50min;獲得較佳抗應力腐蝕性能的雙級固溶工藝為450℃×120min+470℃×40min。(3)回歸再時效中的預時效時間和回歸溫度是影響Al-5.8Zn-2.7Mg-1.6Cu鋁合金性能的最主要因素。通過正交試驗結果得出:Al-5.8Zn-2.7Mg-1.6Cu鋁合金獲得較佳的抗應力腐蝕性能的回歸再時效工藝是 120℃×24h+185℃×1h+120℃×18h。(4)Al-5.8Zn-2.7Mg-1.6Cu鋁合金抗應力腐蝕性能較佳的熱處理工藝參數(shù)為:雙級固溶(450℃×120min+470℃×40min)和回歸再時效(120℃×24h+185℃×1h+120℃×18h)。(5)在低溫的腐蝕環(huán)境中,Al-5.8Zn-2.7Mg-1.6Cu鋁合金的抗拉強度雖然提高,但其延伸率降低,應力腐蝕敏感性也提高,抗應力腐蝕性能下降。
[Abstract]:In this paper, the effect of heat treatment on the stress corrosion resistance of Al-5.8Zn-2.7Mg-1.6Cu aluminum alloy is studied. The microstructure and phase composition of aluminum alloy were studied by optical microscope and scanning electron microscope. The mechanical properties of aluminum alloy were tested by tensile test, and the stress corrosion resistance of aluminum alloy was studied by slow strain rate tensile test. The hardness and conductivity of aluminum alloy were also tested. By analyzing the experimental results, the heat treatment process which can make Al-5.8Zn-2.7Mg-1.6Cu aluminum alloy obtain better mechanical properties and stress corrosion resistance is obtained. The main conclusions are as follows: (1) the effect of high temperature preprecipitation on the stress corrosion resistance of Al-5.8Zn-2.7Mg-1.6Cu aluminum alloy was investigated. The pre-precipitation at high temperature can change the size and distribution of precipitated phase in crystal and grain boundary, inhibit anodic dissolution and hydrogen embrittlement, and improve the mechanical properties and stress corrosion resistance of the alloy. After 420 擄C pre-precipitation temperature treatment, the stress corrosion sensitivity of the alloy is the lowest, and the resistance to stress corrosion is enhanced. However, the strength and hardness of Al-5.8Zn-2.7Mg-1.6Cu aluminum alloy can be reduced. The high temperature pre-precipitation process for obtaining better stress-corrosion resistance is 470 鈩，

本文編號：2246693