低Cu含量Al-Mg-Si-Cu合金的T78双级时效

doi:10.7527/S1000-6893.2018.21986

Abstract

Abstract: The tensile properties and intergranular corrosion of an Al-Mg-Si-Cu alloy with small Cu addition during a two-step ageing (T78 temper) consisting of low-temperature pre-ageing at 180℃ and high-temperature re-ageing at 190, 200 and 210℃ Were investigated by the tensile and accelerated corrosion tests. The results show that with the increase of the pre-ageing and re-ageing time or re-ageing temperature, the strength of the alloy decreases gradually, and the corrosion mode changes in the sequence of intergranular corrosion, uniform corrosion and pitting corrosion. After pre-ageing at 180℃ for 2-8 h and re-ageing at 200℃ for 6 h or 210℃ for 2 h, the alloy has the ultimate tensile strength, yield strength and elongation to failure of 380-395 MPa, 360-380 MPa and 12%-15% respectively, accompanied by uniform corrosion. The transmission electron microscopy observations show that during two-step ageing, the decrease in strength of the alloy is attributed to the decrease of β" precipitates and the increase of β' and Q' precipitates, the decreased intergranular corrosion results from the enlarged interspacing between the grain boundary Q precipitates, andthe increased pitting corrosion is due to the precipitate free zones around the constituent Q phase as a result of coarsening.

Key words: aluminum alloy, ageing, precipitate, intergranular corrosion, pitting corrosion

CLC Number:

V252.2

WANG Zhixiu, ZHU Fan, ZHENG Kai, LI Hai. Two step ageing (T78 temper) of an Al-Mg-Si-Cu alloy with small Cu addition[J]. ACTA AERONAUTICAET ASTRONAUTICA SINICA, 2018, 39(8): 421986-421986.

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Two step ageing (T78 temper) of an Al-Mg-Si-Cu alloy with small Cu addition

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