(1. 常州大學(xué) 材料科學(xué)與工程學(xué)院，常州 213164；
2. 常州大學(xué) 江蘇省材料表面科學(xué)與技術(shù)重點實驗室，常州 213164)
摘 要: 采用慢應(yīng)變拉伸試驗、掃描電鏡(SEM)觀察以及電化學(xué)阻抗譜分析，研究峰時效(PA)、雙峰時效(DPA)、回歸再時效(RRA)狀態(tài)下的7003鋁合金在3.5%NaCl(質(zhì)量分?jǐn)?shù))溶液中應(yīng)力腐蝕裂紋擴(kuò)展的特點。結(jié)果表明：應(yīng)力腐蝕裂紋的過程分為兩個階段，即一次裂紋階段與二次裂紋階段，其中二次裂紋擴(kuò)展階段決定材料的應(yīng)力腐蝕敏感性。裂紋擴(kuò)展截面圖及阻抗譜擬合結(jié)果顯示：二次裂紋擴(kuò)展速率vPA＞vDPA＞vRRA。斷口形貌表明：峰時效狀態(tài)二次裂紋沿晶傾向最為嚴(yán)重，雙峰時效次之，回歸再時效最輕微。結(jié)合應(yīng)力-應(yīng)變曲線分析：3種時效狀態(tài)下的應(yīng)力腐蝕敏感性為ISCC(PA)＞ISCC(DPA)＞ISCC(RRA)。
關(guān)鍵字: 7003鋁合金；電化學(xué)阻抗譜；應(yīng)力腐蝕裂紋；一次裂紋；二次裂紋
（1. School of Materials Science and Engineering, Changzhou University, Changzhou 213164, China;
2. Jiangsu Key Laboratory of Materials Surface Science and Technology, Changzhou University, Changzhou 213164, China）
Abstract:The slow strain rate test (SSRT), scanning electron microscopy (SEM) observation and electrochemical impedance spectroscopy(EIS) analysis were applied to study the stress corrosion cracks propagation of 7003 aluminum alloy under peak aging (PA), double peak aging (DPA) and regression reaging (RRA) in aqueous solution of 3.5% NaCl (mass fraction). The results indicate that the stress corrosion cracks propagation consists of two stages, i.e., initial crack propagation and secondary crack growth, and the secondary crack growth stage decides the stress corrosion cracking (SCC) susceptibility. The secondary crack growth rate of 7003 aluminum alloy under various aging states is as follows, vPA>vDPA>vRRA. The highest intergranular fracture tendency under PA is found by the observation of fracture morphology, DPA take the second place, RRA is the slightest. Cooperated with the stress-strain curve analysis ultimately, the SCC trend under various aging treatment in descending order as follows, ISCC(PA)>ISCC(DPA)>ISCC(RRA).
Key words: 7003 aluminum alloy; electrochemical impedance spectroscopy; stress corrosion cracks; initial crack; secondary crack
