| 摘要 |
PROBLEM TO BE SOLVED: To provide a door beam material capable of preventing the stress concentration at the time of bending deformation and the resultant occurrence of fracture in an early stage and increased in the amount of energy absorption as well as in the maximum load. SOLUTION: This material is an extruded material of an Al-Zn-Mg type aluminum alloy containing, by weight, 0.8-1.5% Mg and 4-7% Zn or an Al-Si-Mg type aluminum alloy containing 0.5-1.5% Si and 0.5-1.3% Mg. In this material, the thickness of a recrystallized layer in the surface is made to <=50μm. A fibrous structure is present under the recrystallized layer. Further, the fibrous structure can be present in the surface without the presence of the recrystallized layer.
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