| 摘要 |
PROBLEM TO BE SOLVED: To provide an Al-Mg based alloy having increased hydrogen embrittlement resistance and usable in a hydrogen gas over a long period.SOLUTION: The Al-Mg based alloy for a high hydrogen gas having excellent hydrogen embrittlement resistance has a composition comprising, by mass, 3.0 to 6.0% of Mg and 0.03 to 1.0% of Cu, and has limited contents of Fe and Si as impurities: below 0.15% for Fe and below 0.15% for Si. In the alloy, the distribution density of crystallized grains composed of an Al-Fe-Si compound and having the size of 1 μm or higher equivalent to a circle diameter is 4,000 pieces/mmor lower. Then, the alloy comprises, by mass, one or two kind selected from Mn at 0.02 to 0.8% and Cr at 0.01 to 0.2% in a range satisfying 0.05%≤Mn+Cr≤0.9%. The distribution density of crystallized grains composed of an Al-Mn compound or an Al-Mn-Cr compound and having the size of 0.5 μm or lower equivalent to a circle diameter is controlled to 100,000 pieces/mmor higher, thus, its hydrogen embrittlement resistance can be more improved. |
