日本金属学会誌

J. Japan Inst. Met. Mater, Vol. 79, No. 3 (2015),
pp. 94-99

Hydrogen Embrittlement Properties of an Al-Mg-Zn Series of Alloy with Brilliant

Tadao Fukuta1, Kiyotaka Obunai1, Koichi Ozaki1, Akihiro Tanabe2, Hideki Kanetsuki3, Koji Murakami4 and Makoto Hino5

1Department of Systems Engineering, Faculty of Computer Science and Systems Engineering, Okayama Prefectural University, Soja 719-1197
2Department of Systems Engineering, Graduate School of Computer Science and Systems Engineering, Okayama Prefectural University, Soja 719-1197
3Hikari Light Metals Co., Ltd., Okayama 709-0854
4Industrial Technology Research Institute of Okayama Prefectural Government, Okayama 701-1296
5Department of Mechanical Systems Engineering, Hiroshima Institute of Technology, Hiroshima 731-5193

Abstract:

The purpose of this study is to investigate the hydrogen embrittlement property of an Al-Mg-Zn series of alloy and to propose the effective concepts to prevent the hydrogen embrittlement for automotive wheels which have shiny appearance without plating. The three types of casted an Al-Mg-Zn series of alloys in which weight fraction of Zn was 3.1, 3.4 and 4.1 mass% were prepared to discuss the effect of Zn fraction on its hydrogen embrittlement characteristics. T6 treatment was applied these alloys to improve its mechanical properties. The hydrogen embrittlement characteristics were evaluated by constant load tensile test under constant temperature. 1 mass% of NaCl solution was dropped to notch of the specimen to evaluate the time until fracture under controlled corrosive environment. Hydrogen generation under corrosive environment and microscopic segregations of materials were also evaluated. Test results were as follows: The rate of diminution in tensile strength at corrosive environment was increased with the increase of the weight fraction of Zn. Microscopic observation showed that the hydrogen generation was active at around the segregation and the number of segregations was increased with the increase of the weight fraction of Zn. According to these results, a reduction in the number and size of segregation is an effective way to prevent hydrogen embrittlement. [doi:10.2320/jinstmet.JC201401]


(Received 2014/8/22)

Keywords:

aluminum alloy, heat treatments, automotive wheel, hydrogen embrittlement


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