Magnesium alloy sheet processing method and magnesium alloy sheet

Abstract

A magnesium alloy sheet processing method wherein a magnesium alloy sheet is rolled at a speed of 180 m / min or more. Particularly, a magnesium alloy sheet processing method, wherein the magnesium alloy sheet is rolled at a speed of 450 m / min or more. A magnesium alloy sheet processing method, wherein a rolling tool which is not heated is used. A magnesium alloy sheet processing method, wherein the temperature of the magnesium alloy sheet immediately before the rolling is in the range of 0° C. to 400° C. A magnesium alloy sheet, wherein the sheet has an average crystal grain of 4 μm or less, and does not internally include any unbonded interface in parallel with a direction of rolling. A magnesium alloy sheet, wherein the sheet has an average grain size of 4 μm or less, and has an internal grain boundary formed by a clean grain boundary.

Description

TECHNICAL FIELD [0001] The present invention relates to a magnesium alloy sheet processing method and a magnesium alloy sheet, and in particular relates to a method for rolling a magnesium alloy sheet at a speed as high as 180 m / minor more, and to a magnesium alloy sheet having an excellent mechanical strength and the like. BACKGROUND ART [0002] Since a magnesium alloy has a high specific strength and an excellent electromagnetic wave absorption characteristic, the utilization thereof is being increased in casings or the like for portable electronic devices such as mobile phones. Actually, a magnesium alloy has a crystal lattice with a close-packed hexagonal structure, and has, at a room temperature, a deformation mechanism consisting mainly of a basal plane slip that causes deformation in a direction perpendicular to the c axis, thus making it significantly difficult to provide a plastic strain (deformation) of 10% or more at an ambient temperature. Therefore, in order to carry out...

AI Technical Summary

Benefits of technology

[0104] In the present invention, rolling is carried out at a speed as high as 180 m / min or more; therefore, even a magnesium alloy sheet, which has been considered as being unable to be rolled to a high rolling reduction in one pass due to its low intrinsic deformability at a low temperature, can be rolled to a high rolling reduction in one pass at a low temperature.

[0105] Further, in the magnesium alloy sheet, crystal grains are refined during the rolling that applies a high rolling reduction, and the sheet is rapidly cooled so that the crystal grains are kept refined, thus improving mechanical properties such as strength and the like.

[0106] Furthermore, reheating (intermediate annealing) during each pass is unnecessary.

[0107] Thus, the mass production of thin magnesium alloy sheets and outstanding cost reduction are enabled.

[0108] Moreover, the present invention can provide thin sheets and casings for portable devices made of magnesium alloy, which are lightweight, have smooth surfaces and good appearances.

Problems solved by technology

Actually, a magnesium alloy has a crystal lattice with a close-packed hexagonal structure, and has, at a room temperature, a deformation mechanism consisting mainly of a basal plane slip that causes deformation in a direction perpendicular to the c axis, thus making it significantly difficult to provide a plastic strain (deformation) of 10% or more at an ambient temperature.

In addition, when rolling is to be carried out, a longitudinal cracking will occur in a material unless the speed at each pass is reduced.

Accordingly, a magnesium alloy has been considered as an unsuitable material for rolling.

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