| 摘要 |
PURPOSE:To reduce a high-temp. welding crack of an extrudate by incorporating a specific amt. of Mn, Cr and other elements in an existing Al-Mg-Si alloy, subjecting the cast ingot thereof to a soaking treatment and extruding the ingot. CONSTITUTION:An Al alloy for extrusion contg. 0.4-1.5% Mg, and 0.2-1.3% Si is added and incorporate therein with 0.05-0.4% Mn, 0.01-0.5% Cu, 0.01- 0.3% Cr, 0.05-0.8% Fe, and 0.0001-0.3% Ti and B in total. After the cast ingot of such alloy is subjected to a soaking treatment at 450-600 deg.C, the ingot is extruded at 400-550 deg.C to adjust the structure of the thick walled section to the fibrous structure or the structure in which the crystal grain size perpendicular to the extruding direction is <=200mu. If such extrudate is welded as a base material 1, the generation of a high temp. crack 3 near a weld zone 2 as in convestional practice is prevented.
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