Aluminum alloy sheet

Abstract

The present invention relates to an Al-Mg-Si aluminum alloy sheet which contains, in terms of mass%, 0.3-1.0% Mg, 0.5-1.5% Si, 0.005-0.2% Sn, 0.02-1.0% Fe, and 0.02-0.6% Mn, with the remainder comprising Al and unavoidable impurities, characterized by having a structure wherein compounds that are detected with an SEM having a magnification of 500 diameters and are identified with an X-ray spectrometer include Sn compounds which contain Mn and Fe and which have an Sn content of 1.0 mass% or higher and a diameter of 0.3-20 [mu]m in terms of equivalent circular diameter, the average number density of the Sn compounds being 500-3,000 grains / mm2, and wherein the length of the boundary between each Sn compound grain and the aluminum matrix is in the range of 3-20 / mm on average in terms of value obtained by dividing the overall circumferential length of the Sn compound grain by the area thereof determined with the SEM. This aluminum alloy sheet satisfies the formability after room-temperature aging and bake hardenability which are required of automotive outer panels, and has excellent filiform rust resistance.

Description

technical field [0001] The present invention relates to an Al-Mg-Si based aluminum alloy plate, and in particular to an aluminum alloy plate excellent in formability, BH property and corrosion resistance. The aluminum alloy sheet referred to in the present invention is a rolled sheet such as a hot-rolled sheet or a cold-rolled sheet, and refers to an aluminum alloy sheet that has been subjected to quenching and tempering such as solution treatment and quenching treatment and before baking, coating and hardening treatment. alloy plate. In addition, aluminum is also called Al in the following description. Background technique [0002] In recent years, society has increasingly demanded weight reduction of vehicles such as automobiles in consideration of the global environment and the like. In order to meet this demand, as a material for automobile panels, especially large body panels (outer panels, inner panels) such as hoods, doors, and roofs, instead of steel materials such...

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Problems solved by technology

[0005] This 6000-series aluminum alloy has the advantage of having excellent BH properties (bake hardenability), but on the other hand, it has room temperature aging properties, and age hardening occurs by keeping at room temperature after solution quenching treatment to increase the strength. This has the problem of reducing the formability of the panel

Furthermore, the following problems also arise: in the case of such a large room temperature aging, the BH property is lowered, and the yield strength remains unchanged by heating during a relatively low-temperature artificial aging (hardening) treatment such as a coating and baking treatment of the formed panel. Cannot be raised to the strength required as a panel

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