低Cu含量Al-Mg-Si-Cu合金的T78双级时效

王芝秀; 朱凡; 郑凯; 李海

doi:10.7527/S1000-6893.2018.21986

航空学报 >

2018 , Vol. 39 >Issue 8: 421986 - 421986

DOI: https://doi.org/10.7527/S1000-6893.2018.21986

材料工程与机械制造

低Cu含量Al-Mg-Si-Cu合金的T78双级时效

王芝秀 ,
朱凡 ,
郑凯 ,
李海

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1. 常州大学材料科学与工程学院, 常州 213164;
2. 江苏省材料表面科学与技术重点实验室, 常州 213164

收稿日期: 2018-01-02

修回日期: 2018-03-07

网络出版日期: 2018-03-07

基金资助

国家自然科学基金（51671038，51571038）；江苏省自然科学基金（BK20151188，BK20171195）

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

WANG Zhixiu ,
ZHU Fan ,
ZHENG Kai ,
LI Hai

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1. School of Materials Science and Engineering, Changzhou University, Changzhou 213164, China;
2. Jiangsu Key Laboratory of Materials Surface Science and Technology, Changzhou 213164, China

Received date: 2018-01-02

Revised date: 2018-03-07

Online published: 2018-03-07

Supported by

National Natural Science Foundation of China (51671038, 51571038);Natural Science Foundation of Jiangsu Province (BK20151188, BK20171195)

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摘要

采用拉伸和加速腐蚀试验，分别测试了预时效（180℃）+再时效（190、200、210℃）对一种低Cu含量Al-Mg-Si-Cu合金拉伸性能和晶间腐蚀的影响，结果表明，延长预时效和再时效时间或提高再时效温度，合金强度逐渐降低，同时，腐蚀类型按晶间腐蚀→均匀腐蚀→坑蚀顺序演化。其中，经预时效（180℃/2~8 h）+再时效（200℃/6 h或210℃/2 h）处理，合金抗拉强度、屈服强度和延伸率分别为380~395 MPa、360~380 MPa和12%~15%，腐蚀类型为均匀腐蚀，实现强度与耐蚀性的良好配合。透射电镜观察表明，随着双级时效程度的增加，合金强度的降低源于基体β"相的减少及β'相和Q'相的增加；晶间腐蚀倾向的降低与晶界Q相大间距、断续分布有关；坑蚀的形成则与结晶Q相吸收周围析出相、形成基体无析出区有关。

关键词： 铝合金; 时效; 析出相; 晶间腐蚀; 坑蚀

本文引用格式

王芝秀 , 朱凡 , 郑凯 , 李海 . 低Cu含量Al-Mg-Si-Cu合金的T78双级时效[J]. 航空学报, 2018 , 39(8) : 421986 -421986 . DOI: 10.7527/S1000-6893.2018.21986

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

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