Cold-rolling method for a wrought mg alloy with weak/non-basal texture and a cold rolled sheet

a cold rolling and weak technology, applied in metal rolling, metal rolling arrangements, etc., can solve the problems of low competitive power of texture, poor ductility, workability and formability of mg alloys, and limits the further press formability and industrial applications of mg alloys, so as to achieve enhanced yield strength and ultimate tensile strength of said billets, the effect of increasing the strength of basal texture components

Inactive Publication Date: 2012-11-15
INST OF METAL RESEARCH - CHINESE ACAD OF SCI
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Benefits of technology

[0020]1) In the invention, a large strain cold rolling is employed to process the wrought Mg alloy with a weak or non-basal texture at room temperature. High density of dislocations and a certain amount of twins can be introduced in the microstructure, and the intensity of basal texture component is increased during the cold-rolling process. Therefore, the yield strength and ultimate tensile strength of said billet are obviously enhanced. The cold rolled sheet has a relatively high strength at room temperature. The method is easy to manipulate and control.
[0021]2) By the proper annealing treatment after this cold-rolling process in the invention, the grain size of the cold-rolled sheet may turn to be finer, and its basal texture component may turn to be weak again, due to the partly or completely recrystallization during the annealing treatment. Compared with the original billet of the wrought Mg alloy with a weak or non-basal texture, the strength is greatly enhanced while ensuring a high ductility. Its mechanical properties may meet the requirement for further processing or application in a comprehensive range.
[0022]3) The original billet of the wrought Mg alloy with a weak or non-basal texture is eventually cold rolled to thin sheets or foils with the thickness of 0.1 to 100 mm in the invention. The strength of the cold-rolled sheet can be enhanced by no less than 15% along the rolling direction; then appropriate annealing treatment is adopted to the cold-rolled sheet, so the strength of the annealed cold-rolled sheet can be increased by no less than 10%, while ensuring a relatively high elongation (δ≧25%) along the rolling direction, in comparison with the original billet of the wrought Mg alloy with a weak or non-basal texture. The strength of the cold rolled sheet is increased significantly, or the ultimate product of this invention exhibits high strength, accompanied with excellent ductility.
[0023]4) The cold-rolled sheets produced by this invention show high surface finish quality, and its final size, especially the thickness, easily meet the dimension tolerance.

Problems solved by technology

Thus, Mg alloys has a poor ductility, workability and formability at middle to low temperature and room temperature, which limits their further press formability and industrial applications.
Thereby, the wrought Mg alloy with a weak or non-basal texture presents a low competitive power and its application is severely limited.
Cold-rolling process is mainly employed to produce thin sheets and belts, which can solve the problems that the size of the hot rolled sheet oversteps the tolerance and the mechanical properties in the same sheet are not uniform, due to the heat drop and non-uniform distribution of temperature during hot rolling.
Nevertheless, the cold rolling response of the conventional wrought Mg alloy sheets, such as AZ31 rolled sheet, is generally poor due to its low ductility at room temperature, as shown in FIG. 1 (a), and it is easy to produce cracks in the surface or side margin when a reduction per pass is more than 10% at room temperature, as shown in FIG. 1 (b), thus it is improper for the conventional Mg alloy sheet to be cold rolled in commercial process, that is, a relatively large stain cold-rolling process.

Method used

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  • Cold-rolling method for a wrought mg alloy with weak/non-basal texture and a cold rolled sheet
  • Cold-rolling method for a wrought mg alloy with weak/non-basal texture and a cold rolled sheet
  • Cold-rolling method for a wrought mg alloy with weak/non-basal texture and a cold rolled sheet

Examples

Experimental program
Comparison scheme
Effect test

example 2

[0033]1) A hot-rolled sheet of a Mg-3Gd-Zn (GZ31 Mg alloy), with a thickness of 3 mm, was selected as a billet. The chemical composition of the GZ31 Mg alloy was, by weight, 2.8% Gd, 1.1% Zn, and Mg being the balance. The elongation-to-failure δ of the hot-rolled sheet along RD was 35%, and the grain size was 20 μm, as shown in FIG. 3 (a). A plane formed by the rolling direction (RD) and the transverse direction (TD) of the hot-rolled sheet was selected as the reference plane, as shown in FIG. 2(a). The maximum intensity of its (0002) pole figure was 1.80, as shown in FIG. 4(a). Thus, the hot-rolled sheet was a wrought Mg alloy with a weak texture, and the selected reference plane of the billet was the weak texture plane.

[0034]2) The specimens with a dimension of 40 mm×25 mm×3 mm were cut out of the GZ31 hot-rolled sheets, and the surface thereof was polished with a waterproof abrasive paper to 800#, as shown in FIG. 2(a). Then they were rolled at room temperature (about 25° C.). Th...

example 3

[0037]1) A hot-rolled sheet of a Mg-2Zn-Y alloy, with a thickness of 3 mm, was selected as a billet. The chemical composition of the Mg-2Zn-Y alloy was, by weight, 1.9% Zn, 1.1% Y, and Mg being the balance. The 0.2% yield strength, ultimate tensile strength, and elongation-to failure δ of the hot-rolled sheet along TD were 122 MPa, 225 MPa, and about 26%, respectively. The grain size was ˜15 μm. A plane formed by the rolling direction (RD) and the transverse direction (TD) of the hot-rolled sheet was selected as the reference plane. The position of the maximum intensity of its (0002) pole figure tilted about 28° from ND. Thus, the hot-rolled sheet was a wrought Mg alloy with a non-basal texture, and the selected reference plane of the billet was the non-basal texture plane.

[0038]2) The specimens with a dimension of 40 mm×25 mm×3 mm were cut out of the hot-rolled sheets, and the surface thereof was polished with a waterproof abrasive paper to 800#. Then they were rolled at room tempe...

example 4

[0041]1) A hot-rolled sheet of a Mg—Y alloy, with a thickness of 3 mm, was selected as a billet. The chemical composition of the Mg—Y alloy was, by weight, 1.2% Y, and Mg being the balance. The 0.2% yield strength, ultimate tensile strength, and elongation-to failure δ of the hot-rolled sheet along RD were 134 MPa, 209 MPa, and about 39%, respectively. The grain size was ˜20 μm. A plane formed by the rolling direction (RD) and the transverse direction (TO) of the hot-rolled sheet was selected as the reference plane. The maximum intensity of its (0002) pole figure was 3.4. Thus, the hot-rolled sheet was a wrought Mg alloy with a weak texture, and the selected reference plane of the billet was the weak texture plane.

[0042]2) The specimens with a dimension of 40 mm×25 mm×3 mm were cut out of the hot-rolled Mg—Y sheets, and the surface thereof was polished with a waterproof abrasive paper. Then they were rolled at room temperature (about 25° C.). The weak texture plane, i.e. the plane f...

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Abstract

The present invention relates to a cold-rolling method for cold-rolling a wrought Mg alloy with a weak or non-basal texture as well as a cold-rolled sheet, the method comprising the steps of: pre-treating a billet of the wrought Mg alloy with a weak or non-basal texture, and then cold rolling it; wherein the weak or non-basal texture plane of said billet is selected as a rolling plane, and the rolling direction is parallel to the rolling plane; and said billet is cold rolled at room temperature to a sheet or foil with a thickness of 0.1 to 100 mm, wherein single-pass or multi-pass rolling is used, and the cold rolling is followed by an annealing at 200 to 400° C. for 10 min to 48 h.

Description

TECHNICAL FIELD OF THE INVENTION[0001]The present invention relates to a cold-rolling technique for manufacturing a cold rolled Mg sheet with excellent mechanical properties, which is featured to obviously enhance the strength of the wrought Mg alloy with weak / non-basal texture by the large stain cold-rolling.BACKGROUND OF THE INVENTION[0002]Compared with materials, such as plastics, woods, and other metals, magnesium and its alloys are more attractive candidates for a number of structural applications due to their high specific strength and stiffness, excellent damping capacity, good electromagnetic shielding, good machinability, and ease to be recycled. Therefore, they are progressively used in automotive, electronic and consumer electric appliance, leisure and gymnasium apparatus, bicycle, aviation, aerospace and defense industries. They are called “the Green Engineering Materials in the 21st Century”, and it can be expected that the consumption of Mg alloy as metallic structural...

Claims

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Application Information

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Patent Type & Authority Applications(United States)
IPC IPC(8): B21B3/00C22C23/00C22F1/06
CPCC22F1/06C22C23/06C22C23/04
Inventor CHEN, RONGSHIWU, DIHAN, ENHOUKE, WEI
Owner INST OF METAL RESEARCH - CHINESE ACAD OF SCI
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