Low-cost fine-grain weak-texture magnesium alloy sheet and method of manufacturing the same

Abstract

The present invention discloses a MgCaZnZr magnesium alloy sheet, having the chemical compositions in weight percentage: Ca: 0.51.0%, Zn: 0.41.0%, Zr: 0.51.0%, the remainders being Mg and unavoidable impurities; wherein the magnesium alloy sheet has an average grain size of less than or equal to 10 m, an interarea texture strength of less than or equal to 5, an interarea texture strength after annealing at 250400 C. of less than or equal to 3, and a limiting drawing ratio at room temperature of more than AZ31; and the grain size thereof is remarkably less than that of AZ31B sheet produced in the same conditions, and the sheet texture is notably weakened. The magnesium alloy of the present invention has simple chemical compositions without noble alloy elements therein, thereby having a wide applicability and a low manufacturing cost, which can act as the sheets of interior door panels of cars, inner panels of engine lids, inner panels of trunk lids, internal decorative panels, vehicle bodies in the rail transits, and housings of 3C products, or the like.

Claims

1. A MgCaZnZr magnesium alloy sheet, having the chemical compositions in weight percentage: Ca: 0.51.0%, Zn: 0.41.0%, Zr: 0.51.0%, the remainders being Mg and unavoidable impurities; wherein the magnesium alloy sheet has an average grain size of less than or equal to 10 m, an interarea texture strength of less than or equal to 5, an interarea texture strength after annealing at 250400 C. of less than or equal to 3, and a limiting drawing ratio at room temperature of more than 1.74; and the magnesium alloy sheet has a thickness of 0.34 mm.

2. A method of producing the MgCaZnZr magnesium alloy sheet according to claim 1, which is any one of the following methods (1)(3): (1) heating the casting blank of MgCaZnZr magnesium alloy with the aforementioned composition proportions up to a temperature of 370500 C., and carrying out solid solution, then hot rolling and warm rolling, so as to obtain the MgCaZnZr magnesium alloy sheet with a thickness of 0.34 mm; wherein the heat preservation time in the solid solution is 0.51 min/mm; when in the hot rolling, the roller surfaces are preheated at 150350 C., the blooming temperature is 450500 C., the finish rolling temperature is 300350 C., and the reduction rate in a single pass is 2050%; when in the warm rolling, the roller surfaces are preheated up to 150350 C., the magnesium alloy sheet is online concurrent heated, the rolling temperature is 150350 C., and the reduction rate in a single pass is 2040%; (2) pouring the magnesium alloy melt with the aforementioned composition proportions into a twin-roller continuous cast-rolling mill for cast-rolling, so as to obtain the cast-rolling coil; carrying out solid solution and warm rolling, or warm rolling directly, so as to obtain the MgCaZnZr magnesium alloy sheet with a thickness of 0.34 mm; wherein in the cast-rolling process by the twin-roller continuous cast-rolling mill, the rotation linear velocity of the rollers is 5-10 m/min, the roller gap is 4-8 mm, the roller surfaces are lubricated by graphite, and the gases N.sub.2 and CO.sub.2 pass through the smelter and casting system and SO.sub.2 passes through the pouring exit for protection; the temperature of the solid solution is 370500 C., and the heat preservation time thereof is 0.51 min/mm; when in the warm rolling, the roller surfaces are preheated up to 180300 C., the magnesium alloy sheet is online concurrent heated, the rolling temperature is 180300 C., and the reduction rate in a single pass is 2040%; (3) heating the casting blank of magnesium alloy with the aforementioned composition proportions up to a temperature of 370500 C., and carrying out solid solution, then performing horizontal extrusion, so as to obtain the MgCaZnZr magnesium alloy sheet with a thickness of 24 mm, or performing horizontal extrusion and subsequently warm rolling, so as to obtain the MgCaZnZr magnesium alloy sheet with a thickness of 0.32 mm; wherein the heat preservation time in the solid solution is 0.51 min/mm; when in the horizontal extrusion, the extrusion container and die are preheated up to 400500 C., the extrusion temperature is 350500 C., and the extrusion rate is 210 m/min; and when in the warm rolling, the roller surfaces are preheated up to 150300 C., the magnesium alloy sheet is online concurrent heated, the rolling temperature is 150300 C., and the reduction rate in a single pass is 3050%.

3. The method of producing MgCaZnZr magnesium alloy sheet according to claim 2, wherein it further comprises a cold rolling stage, wherein the cold rolling reduction rate is 1020%, and the thickness of the finished sheet is about 0.3 mm.

4. The method of producing MgCaZnZr magnesium alloy sheet according to claim 2, wherein it further comprises an annealing treatment and/or an aging treatment; wherein the annealing temperature is 250400 C., and the aging temperature is 150200 C.

5. The method of producing MgCaZnZr magnesium alloy sheet according to claim 3, wherein it further comprises an annealing treatment and/or an aging treatment; wherein the annealing temperature is 250400 C., and the aging temperature is 150200 C.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) FIG. 1 is a view showing the microstructure of the casting ingot of the MgCaZnZr magnesium alloy according to Embodiment 1 of the present invention.

(2) FIG. 2 is a view showing the texture distribution of the MgCaZnZr magnesium sheet according to Embodiment 1 of the present invention.

(3) FIG. 3 is a view showing the texture distribution of AZ31 magnesium sheet according to Embodiment 2 of the present invention.

(4) FIG. 4 is a view showing the microstructure of the MgCaZnZr magnesium sheet after annealing according to Embodiment 3 of the present invention.

(5) FIG. 5 is a view showing the grain distribution of the annealed MgCaZnZr magnesium sheet according to Embodiment 3 of the present invention.

(6) FIG. 6 is a view showing the texture distribution of the annealed MgCaZnZr magnesium sheet according to Embodiment 3 of the present invention.

(7) FIG. 7 is a view showing the microstructure of the AZ31 magnesium sheet after annealing according to Embodiment 4 of the present invention.

(8) FIG. 8 is a view showing the grain distribution of the annealed AZ31 magnesium sheet.

(9) FIG. 9 is a view showing the texture distribution of the annealed AZ31 magnesium sheet according to Embodiment 4 of the present invention.

(10) FIG. 10 is a view showing the limit drawing ratio at room temperature of the annealed MgCaZnZr magnesium sheet according to Embodiment 3 of the present invention.

(11) FIG. 11 is a view showing the limit drawing ratio at room temperature of the annealed AZ31 magnesium sheet according to Embodiment 4 of the present invention.

(12) FIG. 12 is a view showing the change on hardness of the MgCaZnZr magnesium sheet after aging treatment according to Embodiment 6 of the present invention.

DETAILED DESCRIPTION

(13) Hereinafter the technical solution of the present invention will be further set out in detail in conjunction with the detailed embodiments.

Embodiment 1

(14) The chemical compositions of the MgCaZnZr magnesium sheet are shown as Table 1. The method of producing the same is:

(15) heating the casting blank of magnesium alloy (the microstructure thereof shown as FIG. 1) with the composition proportions required as Table 1, up to 500 C., and carrying out solid solution with a heat preservation time of 0.5 min/mm, then rolling to obtain the MgCaZnZr magnesium alloy of this embodiment. When in the hot rolling, the roller surfaces are preheated up to 150 C., the blooming temperature is 450 C., the finish rolling temperature is 350 C., and the reduction rate in a single pass is 2030%; when in the warm rolling, the roller surfaces are preheated up to 150 C., the magnesium alloy sheet is online concurrent heated, the rolling temperature is 220 C., and the reduction rate in a single pass is 2040%; when in the cold rolling, the reduction rate is 10%, and the final thickness of the sheet is 0.4 mm.

(16) The microstructure of the casting ingot of the magnesium alloy according to Embodiment 1 is shown as FIG. 1, which microstructure is the isometric crystals with an average grain size of about 50 m.

(17) The texture distribution of the MgCaZnZr magnesium alloy sheet according to Embodiment 1 is shown as FIG. 2, with the strength of the texture being 4.4 and the average grain size thereof being 3.85 m.

Embodiment 2: (Contrastive Example 1)

(18) The composition of the magnesium alloy of Contrastive Example 1: AZ31B.

(19) Manufacturing method: identical to that of Embodiment 1.

(20) The texture distribution of the AZ31B magnesium alloy sheet according to Contrastive Example 1 is shown as FIG. 3, with the strength of the texture being 8.

Embodiment 3

(21) The chemical compositions of the MgCaZnZr magnesium sheet are shown as Table 1. The method of producing the same is:

(22) heating the casting blank of magnesium alloy with the composition proportions required as Table 1, up to 500 C., and carrying out solid solution with a heat preservation time of 0.5 min/mm; when in the hot rolling, the roller surfaces are preheated up to 150 C., the blooming temperature is 450 C., the finish rolling temperature is 350 C., and the reduction rate in a single pass is 2030%; when in the warm rolling, the roller surfaces are preheated up to 150 C., the magnesium alloy sheet is online concurrent heated, the rolling temperature is 220 C., and the reduction rate in a single pass is 2040%; when in the cold rolling, the reduction rate is 10%, and the final thickness of the sheet is 0.4 mm; annealing at 375 C. for 17 min.

(23) The microstructure of the casting ingot of the MgCaZnZr magnesium alloy according to Embodiment 3 is shown as FIG. 4; the grain size distribution thereof is shown as FIG. 5, wherein the average grain size is about 4.62 m; the texture distribution thereof is shown as FIG. 6, wherein the texture strength is 2.8, and the distribution is of dispersal. The test of formability is shown as FIG. 10, wherein the limit drawing ratio (LDR) is 1.88.

Embodiment 4: (Contrastive Example 2)

(24) The composition of the magnesium alloy of Contrastive Example 2: AZ31B.

(25) Manufacturing method: identical to that of Embodiment 3.

(26) The microstructure of the magnesium alloy AZ31B in Contrastive Example 2 is shown as FIG. 7; the grain size distribution thereof is shown as FIG. 8, wherein the average grain size is about 22 m; the texture distribution thereof is shown as FIG. 9, wherein the texture strength is 6.2. The test of formability is shown as FIG. 11, wherein the limiting drawing ratio (LDR) is 1.74.

Embodiment 5

(27) The chemical compositions of the MgCaZnZr magnesium sheet are shown as Table 1. The method of producing the same is:

(28) heating the casting blank of magnesium alloy with the composition proportions required as Table 1, up to 500 C., and carrying out solid solution with a heat preservation time of 0.5 min/mm; when in the hot rolling, the roller surfaces are preheated up to 150 C., the blooming temperature is 450 C., the finish rolling temperature is 350 C., and the reduction rate in a single pass is 2030%; when in the warm rolling, the roller surfaces are preheated up to 150 C., the magnesium alloy sheet is online concurrent heated, the rolling temperature is 220 C., and the reduction rate in a single pass is 2040%; when in the cold rolling, the reduction rate is 10%, and the final thickness of the sheet is 0.8 mm; annealing at 375 C. for 35 min.

(29) The MgCaZnZr magnesium alloy obtained according to this Embodiment has an average grain size of about 5.32 m, a texture strength of 2.6, a relatively dispersed texture distribution, and a limit drawing ratio (LDR) of 1.86.

Embodiment 6

(30) The chemical compositions of the MgCaZnZr magnesium sheet are shown as Table 1. The method of producing the same is:

(31) heating the casting blank of magnesium alloy with the composition proportions required as Table 1, up to 500 C., and carrying out solid solution with a heat preservation time of 0.5 min/mm; when in the hot rolling, the roller surfaces are preheated up to 150 C., the blooming temperature is 450 C., the finish rolling temperature is 350 C., and the reduction rate in a single pass is 2030%; when in the warm rolling, the roller surfaces are preheated up to 150 C., the magnesium alloy sheet is online concurrent heated, the rolling temperature is 220 C., and the reduction rate in a single pass is 2040%; when in the cold rolling, the reduction rate is 10%, and the final thickness of the sheet is 0.4 mm; performing the artificial aging treatment at 150 C. The influence of the artificial aging treatment on the hardness of the magnesium alloy is shown in FIG. 12, wherein the hardness of the material rises from HV72 to HV85 after aging treatment for 1 h.

(32) The MgCaZnZr magnesium alloy obtained according to this Embodiment has an average grain size of about 4.4 m, a texture strength of 4.0, a relatively dispersed texture distribution, and a limiting drawing ratio (LDR) of 1.79.

Embodiment 7: (Contrastive Example 3)

(33) The composition of the magnesium alloy of Contrastive Example 3: AZ31B.

(34) Manufacturing method: identical to that of Embodiment 6.

(35) The influence of the aging treatment on the hardness of the magnesium alloy is shown in FIG. 12.

Embodiment 8

(36) The chemical compositions of the MgCaZnZr magnesium sheet are shown as Table 1. The method of producing the same is:

(37) heating the casting blank of magnesium alloy with the composition proportions required as Table 1, up to 500 C., and carrying out solid solution with a heat preservation time of 0.5 min/mm; when in the hot rolling, the roller surfaces are preheated up to 150 C., the blooming temperature is 450 C., the finish rolling temperature is 350 C., and the reduction rate in a single pass is 2040%; when in the warm rolling, the roller surfaces is preheated up to 200 C., the magnesium alloy sheet is online concurrent heated, the rolling temperature is 200 C., and the reduction rate in a single pass is 2040%; when in the cold rolling, the reduction rate is 15%, and the final thickness of the sheet is 0.6 mm.

(38) The MgCaZnZr magnesium alloy obtained according to this Embodiment has an average grain size of about 5.2 m, a texture strength of 4.6, and a relatively dispersed texture distribution.

Embodiment 9

(39) The chemical compositions of the MgCaZnZr magnesium sheet are shown as Table 1. The method of producing the same is:

(40) pouring the magnesium alloy melt with the aforementioned composition proportions into a twin-roller continuous cast-rolling mill with the rotation linear velocity of the rollers being 6 m/min, the roller gap being 4-8 mm, the roller surfaces being lubricated by graphite, the gases N.sub.2 and CO.sub.2 passing through the smelter and casting system, and SO.sub.2 passing through the pouring exit for protection; the temperature of the solid solution being 450 C., and the heat preservation time thereof being 0.51 min/mm; when in the warm rolling, the roller surfaces are preheated up to 180 C., the magnesium alloy sheet is online concurrent heated, the rolling temperature is 180200 C., and the reduction rate in a single pass is 2030%; then cold rolling by 15%, and annealing at 400 C. for 2 h.

(41) The MgCaZnZr magnesium alloy obtained according to this Embodiment has an average grain size of about 8.6 m, a texture strength of 2.6, a relatively dispersed texture distribution, and a limiting drawing ratio (LDR) of 1.89.

Embodiment 10

(42) The chemical compositions of the MgCaZnZr magnesium sheet are shown as Table 1. The method of producing the same is:

(43) heating the casting blank of magnesium alloy with the aforementioned composition proportions up to a temperature of 500 C., and carrying out solid solution with a heat preservation time of 0.5 min/mm; then performing horizontal extrusion, with the extrusion container and die (die cushion) being preheated up to 500 C., the extrusion temperature being 350 C., the extrusion rate being 5 m/min, so as to obtain a magnesium alloy sheet with a thickness of 4 mm; adopting the warm rolling process, with the roller surfaces being preheated up to 150 C., the magnesium alloy sheet being online concurrent heated, the rolling temperature being 150300 C., and the reduction rate in a single pass being 3050%; then cold rolling by 20%, and annealing at 400 C. for 30 min.

(44) The MgCaZnZr magnesium alloy obtained according to this Embodiment has an average grain size of about 8.5 m, a texture strength of 2.8, a relatively dispersed texture distribution, and a limiting drawing ratio (LDR) of 1.88.

Embodiment 11

(45) The chemical compositions of the MgCaZnZr magnesium sheet are shown as Table 1. The method of producing the same is identical to that of Embodiment 8.

(46) The MgCaZnZr magnesium alloy obtained according to this Embodiment has an average grain size of about 5.4 m, a texture strength of 4.6, and a relatively dispersed texture distribution.

Embodiment 12

(47) The chemical compositions of the MgCaZnZr magnesium sheet are shown as Table 1. The method of producing the same is identical to that of Embodiment 9.

(48) The MgCaZnZr magnesium alloy obtained according to this Embodiment as an average grain size of about 6.8 m, a texture strength of 2.8, a relatively dispersed texture distribution and a limiting drawing ratio (LDR) of 1.85.

Embodiment 13

(49) The method of producing the MgCaZnZr magnesium sheet is:

(50) pouring the magnesium alloy melt with the composition proportions of Embodiment 9 into a twin-roller continuous cast-rolling mill, with the rotation linear velocity of the rollers being 6 m/min, the roller gap being 4 mm, the roller surfaces being lubricated by graphite, the gases N.sub.2 and CO.sub.2 passing through the smelter and casting system, and SO.sub.2 passing through the pouring exit for protection; subsequently warm rolling directly, and when in the warm rolling, the roller surfaces are preheated up to 180 C., the magnesium alloy sheet is online concurrent heated, the rolling temperature is 180200 C., and the reduction rate in a single pass is 2030%; then cold rolling by 15%, and annealing at 400 C. for 2 h.

(51) The MgCaZnZr magnesium alloy obtained according to this Embodiment has an average grain size of about 8.9 m, a texture strength of 2.9, a relatively dispersed texture distribution, and a limiting drawing ratio (LDR) of 1.82.

Embodiment 14

(52) The method of producing the MgCaZnZr magnesium sheet is:

(53) heating the casting blank of magnesium alloy with the aforementioned composition proportions up to a temperature of 500 C., and carrying out solid solution with a heat preservation time of 0.5 min/mm; then performing horizontal extrusion, with the extrusion container and die (die cushion) being preheated up to 500 C., the extrusion temperature being 350 C., the extrusion rate being 5 m/min, so as to obtain a magnesium alloy sheet with a thickness of 4 mm; then cold rolling by 20%, and annealing at 400 C. for 30 min.

(54) The MgCaZnZr magnesium alloy obtained according to this Embodiment has an average grain size of about 5.9 m, a texture strength of 2.8, a relatively dispersed texture distribution, and a limiting drawing ratio (LDR) of 1.88.

Embodiment 15

(55) The method of producing the MgCaZnZr magnesium sheet is:

(56) heating the casting blank of magnesium alloy (the microstructure thereof shown as FIG. 1) with the composition proportions required as Table 1, up to 500 C., and carrying out solid solution with a heat preservation time of 0.5 min/mm, then rolling to obtain the MgCaZnZr magnesium alloy of this embodiment. When in the hot rolling, the roller surfaces are preheated up to 150 C., the blooming temperature is 450 C., the finish rolling temperature is 350 C., and the reduction rate in a single pass is 2030%; when in the warm rolling, the roller surfaces are preheated up to 150 C., the magnesium alloy sheet is online concurrent heated, the rolling temperature is 220 C., and the reduction rate in a single pass is 2040%; and the obtained magnesium alloy sheet has a thickness of 0.44 mm, and is subjected to annealing at 300 C. for 30 min.

(57) The MgCaZnZr magnesium alloy obtained according to this Embodiment has an average grain size of about 4.2 m, a texture strength of 2.6, a relatively dispersed texture distribution, and a limit drawing ratio (LDR) of 1.92.

(58) TABLE-US-00001 TABLE 1 unit: wt % Ca Zn Zr Mg/Impurities Embodiment 1 0.72 0.43 0.83 Remainders Embodiment 3 0.72 0.43 0.83 Remainders Embodiment 5 0.72 0.43 0.83 Remainders Embodiment 6 0.72 0.43 0.83 Remainders Embodiment 8 0.60 0.96 0.75 Remainders Embodiment 9 0.65 0.90 0.65 Remainders Embodiment 10 0.79 0.82 0.56 Remainders Embodiment 11 0.95 0.60 0.75 Remainders Embodiment 12 0.50 0.75 0.95 Remainders