| 摘要 |
PURPOSE:To develop an Al-Mg alloy for welded structure having a cryogenic characteristic by decreasing the content of Mn, Fe and Si in a specifically composed Al-Mg alloy and limiting the distributed quantity and size of an eutectic compd. CONSTITUTION:An alloy contains 4-5.5wt% Mg, 0.4-0.80wt% Mn, 0.05- 0.35wt% Cr and 0.005-0.2wt% Ti and has limited contents of Mg, Fe and Si which are the essential components of an eutectic alloy. The total of the contents of Mn and Fe therein is limited to <=0.80wt% and the content of Fe alone is limited to <=0.20wt% and the content of Si as an impurity to <=0.10wt%. The distributed quantity of the eutectic alloy of Al-Fe-Mn and Al-Mg-Si is decreased and the eutectic mixture is fined and dispersed, by which the Al alloy for welded structure having an excellent mechanical characteristic at an extra low temp. and suitable as a raw material for the member to be used for transportation and storage of LNG is obtd.
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