Aluminum alloy sheet with excellent baking-paint curability

Abstract

This aluminum alloy sheet is a 6000-series aluminum alloy sheet of a specific composition which, after rolling, has undergone solution hardening and reheating as tempering treatments. The aluminum alloy sheet in differential scanning calorimetry gives a curve in which the exothermic-peak heights A, B, and C in respective specific temperature ranges have relationships within specific given ranges to thereby raise the increase in 0.2% proof stress through low-temperature short-time artificial age-hardening to 100 MPa or more.

Description

technical field [0001] The invention relates to an Al-Mg-Si series aluminum alloy plate. The aluminum alloy sheet in the present invention is a rolled sheet such as a hot-rolled sheet or a cold-rolled sheet. Aluminum alloy plate before treatment. In addition, in the following description, aluminum is also called Al. Background technique [0002] In recent years, there has been an increasing social demand for weight reduction of vehicles such as automobiles in consideration of the global environment and the like. In order to respond to this demand, as a material for automobile panels, especially large body panels (outer panels, inner panels) such as hoods, doors, and roofs, it replaces steel materials such as steel sheets, and has excellent formability and bake hardenability. The use of lighter aluminum alloys is increasing. [0003] Among them, as thin-walled and high-strength aluminum As the plate, an Al—Mg—Si based AA or JIS 6000 series (hereinafter also referred to a...

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Problems solved by technology

[0012] However, in this patent document 3, it is also difficult to reduce the As yield strength of the aluminum alloy plate immediately after tempering treatment (manufacturing) to less than 135 MPa, after baking coating hardening (after applying 2% strain, 170°C×20 The yield strength after BH is close to 240MPa, or becomes a high yield strength above this

That is, it is difficult to have a bake-coat hardening characteristic (BH property) in which the difference between the yield strength after BH and the As yield strength is 120 MPa or more

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