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Acta Metall Sin  2013, Vol. 49 Issue (2): 243-250    DOI: 10.3724/SP.J.1037.2012.00509
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LI Xiangliang, CHEN Jianghua, LIU Chunhui, FENG Jiani, WANG Shihao
College of Materials Science and Engineering, Hunan University, Changsha 410082
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Although AlMgSi (6000-series) are generally considered to have better corrosion resistance than other aluminum alloys, it may introduce susceptibility to intergranular corrosion (IGC) by some factors, for instance, improper thermo-mechanical treatment and high Cu content. So the T78 treatment has been designed to desensitize it to IGC. In this paper, effects of T6 and T78 tempers on the microstructures and properties of an Al-0.75Mg-0.75Si-0.8Cu (mass fraction, %) were investigated by hardness test, electric conductivity test,accelerated corrosion test, SEM, TEM and energy dispersive X-ray elemental mapping. The hardness and conductivity of the T6 peak-aged sample, which was obtained by artificial aging for 8 h at 180 ℃, were 128.3 HV and 27.3~106 S/m, respectively. T78 tempers involved a first step aging (180 ℃, 5 h) followed by a second step aging at 195, 205 and 215 ℃, respectively.With the prolonging of second step aging, the hardness firstly decreased then increased, while the conductivity increased gradually. The optimum T78 process was(180 ℃, 5 h)+(195 ℃, 2 h), at which condition the hardness was 129.2 HV and the electric conductivity was 27.6~106 S/m. TEM observation results show that it was mostly needle-likeβ” phase in the Al matrix for the peak-aged sample. After T78 treatment, a large amount of lath-like precipitates formed in the matrix, while the precipitate free zones (PFZ) broadened slightly. The segregation of Cu was found at the interface between lath-like precipitates and the matrix, so more Cu precipitated out from the Al matrix and thus reduced the electrochemical potential difference between the PFZ and the matrix. The above finding may explain why T78 temper can desensitize intergranular corrosion without sacrificing strength.

Key words:  aluminum alloy      precipitate      grain boundary      intergranular corrosion, microstructure     
Received:  31 August 2012     

Cite this article: 

LI Xiangliang, CHEN Jianghua, LIU Chunhui, FENG Jiani, WANG Shihao. EFFECTS OF T6 AND T78 TEMPERS ON THE MICROSTRUCTURES AND PROPERTIES OF Al-Mg-Si-Cu ALLOYS. Acta Metall Sin, 2013, 49(2): 243-250.

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[1] Chen J H, Liu C H. Trans Nonferrous Met Soc China, 2011; 21: 2352

(陈江华, 刘春辉. 中国有色金属学报, 2011; 21: 2352)

[2] Chen J H, Costan E, Van Huis M A, Xu Q, Zandbergen H W. Science, 2006; 312: 416

[3] Guinier A. Nature, 1938; 142: 570

[4] Tian N, Zhao G, Zuo L, Liu C M. Acta Metall Sin, 2010; 46: 613

(田妮, 赵刚, 左良, 刘春明. 金属学报, 2010; 46: 613)

[5] Liu Y N, Chen J H, Yin M J, Liu C H, Wu C L, Zhao X Q. J Chin Electron Microsc Soc, 2010; 29: 280

(刘亚妮, 陈江华, 尹美杰, 刘春辉, 伍翠兰, 赵新奇. 电子显微学报, 2010; 29: 280)

[6] Zhan H, Mol J M C, Hannour F, Zhuang L, Terryn H. Mater Corros, 2008; 59: 670

[7] Larsen M H, Walmsley J C, Lunder O T, Nisancioglu K. Mater Sci Forum, 2006; 519: 667

[8] Dif R, Bes B, Warner T, Lequeu P, Ribes H, Lassinccp P. Advances in the Metallurgy of Aluminum Alloys. Ohio: AMS International Publications, 2001: 390

[9] Williams J C, Starke E A. Acta Mater, 2003; 51: 5775

[10] Tanaka M, Warner T. Mater Sci Forum, 2000; 331: 983

[11] Shi A, Shaw B A, Sikora E. Corros Sci Sect, 2005; 61: 534

[12] Sinyavskii V S, Ulanova V V, Kalinin V D. Prot Met, 2004; 40: 537

[13] Liao Y F, Chen J H, Liu C H, Li X L, Feng J N. J Chin Electron Microsc Soc, 2012; 31: 116

(廖元飞, 陈江华, 刘春辉, 李祥亮, 冯佳妮. 电子显微学报, 2012; 31: 116)

[14] Vukmirovic M B, Dimitrov N, Sieradzk K. J Electrochem Soc, 2002; 149: B428

[15] Svenningsen G, Larsen M H, Walmsley J C, Nordlien J H, Nisancioglu K. Corros Sci, 2006; 48: 1528

[16] Li H , Pan D Z, Wang Z X, Zheng Z Q. Acta Metall Sin, 2010; 46: 494

(李海, 潘道召, 王芝秀, 郑子樵. 金属学报, 2010; 46: 494)

[17] Zandbergen H W, Andersen S J, Jansen J. Science, 1997; 277: 1221

[18] Marioara C D, Andersen S J, Stene T N, Hasting H, Walmsley J C, Van Heelvort A T J, Holmestad R. Philos Mag, 2007; 87: 3385

[19] Chakrabarti D J, Laughlin D E. Prog Mater Sci, 2004; 49: 389

[20] Tors{\aeter M, Lefebvre W, Marioara C D, Andersen S J, Walmsley J C, Holmestad R. Scr Mater, 2011; 64: 817

[21] Arnberg L, Aurivillius B. Acta Chem Scand Ser A, 1980; 34: 1

[22] Wang X, Esmaeili S, Lloyd D J. Metall Mater Trans, 2006; 37A: 2691

[23] Hasting H S, Walmsley J C, Van Helvoort A T J, Marioara C D, Andersen S J, Holmestad R. Philos Mag Lett, 2006; 86: 589

[24] Van Huis M A, Chen J H, Zandbergen H W, Sluiter M H F. Acta Mater, 2006; 54: 2945

[25] Esmaeili S, Vaumousse D, Zandbergen M W, Poole W J, Cerezo A, Lloyd D J. Philos Mag, 2007; 87: 3797

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