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
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]
aluminum alloy, heat treatments, automotive wheel, hydrogen embrittlement
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