Aluminum alloy forging material for welded structural parts and manufacturing method thereof

Abstract

The present invention provides an aluminum alloy forging material for welded structural parts that maintains tensile strength and is excellent in weld crack resistance and stress corrosion crack resistance, and a method for producing the same. The aluminum alloy forged material (1) for welded structural parts is characterized in that, in the microstructure of the aluminum alloy forged material (1) for welded structural parts, when the grain length of the major axis is GL μm, and the grain length of the minor axis is GS μm , among the three mutually perpendicular planes observed at the site where the shear band is formed, two planes are represented by the following formula, and the crystal grains (4) of the remaining plane are curved in the major axis direction. 50≤GL≤500...(1), 10≤GS≤180...(2), GS≤GL...(3).

Description

technical field [0001] The invention relates to an aluminum alloy forging suitable for welding structural components and a manufacturing method thereof. Background technique [0002] As structural members of transportation vehicles such as automobiles, motorcycles, railway vehicles, and airplanes, for example, 7000-series aluminum alloy materials that are high in strength and excellent in corrosion resistance are widely used. (Hereafter, "aluminum alloy" is described as "Al alloy".) [0003] Al alloy forgings based on 7N01, which is a representative alloy of 7000-series Al alloys, are produced by hot forging at a temperature of 350 to 500°C, followed by solution treatment at a temperature of 400 to 500°C, Thereafter, the natural aging treatment was not performed, but the artificial aging treatment was performed and manufactured. [0004] For example, Patent Document 1 discloses a method for manufacturing an Al alloy forged product, which is characterized in that it include...

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Problems solved by technology

[0009] However, among existing aluminum alloy forging materials, when using 7000-series Al alloy as a weldable forging material, it is known that it is an alloy that is difficult to weld compared with iron and 5000-series Al alloy.

That is, 7000-series Al alloys are prone to defects such as welding cracks if the components and manufacturing conditions are not properly selected.

[0010] In addition, in the conventional aluminum alloy forging material, when welding is performed perpendicularly from the elongation direction of the crystal grains, there is a problem that cracks tend to progress along the grain boundaries.

[0011] In addition, the method disclosed in Patent Document 1 only stipulates the composition of the aluminum alloy, but the performance of the forged material varies greatly depending on the manufacturing conditions, and the reproducibility of the performance of the forged material is poor.

In addition, in Patent Document 1, since the grain size and grain shape are not sufficiently studied, it can be said that cracks are likely to occur depending on the welding conditions.

[0012] Thus, regarding cracks during welding, the relationship between grain size and grain shape has not been sufficiently verified so far.

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