<正> 目前关于铝合金的应力腐蚀开裂(SCC)的研究较多地集中在Al-Zn-Mg-Cu系超硬铝的热处理工艺和电化学腐蚀机理等方面,对于锻铝合金的应力腐蚀研究得较少。Al-Mg-Si系低强度锻铝合金(如LD2)产生晶间腐蚀,不产生应力腐蚀。Al-Cu-Mg-Si系高强度锻铝合金有较强的应力腐蚀倾向,国外有少量报导,国内曾出现这类合金的应力腐蚀破坏。研究这类锻铝合金显微组织特征与应力腐蚀开裂机制间关系,有利于全面阐明铝合金应力腐蚀的理论。
Stress corrosion cracking of high strength forged aluminium alloy LD10, containing 4.4％ Cu, 0.6％ Mg and 0.8％ Si, has been studied. It is found that the response of SCC resistance and strength to heat treatment of Al-Cu-Mg-Si alloy is different from that of Al-Zn-Mg-Cu alloy in some aspects. For Al-Zn-Mg-Cu alloys, a two-step aging improves the resistance against SCC, but always with decreased tensile strength. On the other hand, after two-step aging (1600℃×8h+190℃×2h) Al-Cu-Mg-Si alloy can reach a high resistance against SCC (K_(1SCC) is large than 17 MPam~(1/2) SCC growth rate is about 10~(-10)m/see) and a high tensile strength.Attention is fucused on the microstructure at grain boundaries because of the intergranular fracture characteristics of SCC. It is found SCC sensitivity on LD10 alloy varies with the precipitation phases: GP zone and θ″ phase are sensitive to SCC; the continuous θ′ phase is most sensitive to SCC; while the discontinuous stable θ phase is not sensitive to SCC at all.
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