MAGNESIUM ALLOY, PREPARATION METHOD OF MAGNESIUM ALLOY SECTION BAR AND PREPARATION METHOD OF MAGNESIUM ALLOY RIM

Abstract

The present invention discloses a magnesium alloy, a preparation method of a magnesium alloy section bar and a preparation method of a magnesium alloy rim, wherein the magnesium alloy contains the following components in percentage by weight: 5.5-6.0% of Zn, 0.3-0.6% of Zr, 0.5-2.0% of lanthanum-rich mixed rare earth and the balance of Mg.

Claims

1. A magnesium alloy, comprising the following components in percentage by weight: 5.5-6.0% of Zn, 0.3-0.6% of Zr, 0.5-2.0% of yttrium-rich mixed rare earth and the balance of Mg.

2. The magnesium alloy according to claim 1, wherein the yttrium-rich mixed rare earth consists of Y and other rare earth elements, and the content of Y is 25-30 wt %.

3. The magnesium alloy according to claim 2, wherein the yttrium-rich mixed rare earth comprises the following earths in percentage by weight: 25-30% of Y, 15-20% of Nd, 12-16% of Gd, 10-15% of Dy and the balance of other rare earths.

4. The magnesium alloy according to claim 3, wherein the yttrium-rich mixed rare earth consists of the following raw materials in percentage by weight: 25-30% of Y, 15-20% of Nd, 12-16% of Gd, 10-15% of Dy, 8-12% of La, 6-10% of Ce, 3-6% of Pr, 2-5% of Ho and 1-3% of Er.

5. A preparation method of a magnesium alloy section bar used as a bicycle rim, comprising the following steps: 1) preparing magnesium alloy bar stock according to a component formula of the magnesium alloy according to claim 1; 2) putting the magnesium alloy bar stock and a bicycle rim section bar mold into a heating furnace for heating to 300-400° C., and then taking the magnesium alloy bar stock out and putting into an extruder preheated to 300-380° C. in advance for rim section bar extrusion production to obtain a magnesium alloy section bar which meets the requirements for rim mechanical properties.

6. The preparation method of a magnesium alloy section bar used as a bicycle rim according to claim 5, wherein in step 1), a preparation method of the magnesium alloy bar stock comprises the following steps: (1) material preparation: preparing materials according to a component formula and melting weight of the magnesium alloy bar stock, wherein Zr is added in the form of Mg-5Zr master alloy, and yttrium-rich mixed rare earth is added in the form of Mg-10Re rare earth master alloy; (2) melting: charging a prepared magnesium ingot into a crucible heating furnace, covering the upper surface of the magnesium ingot with a layer of a magnesium alloy smelting covering agent, heating the furnace charge to 700-730° C., and after the magnesium ingot is completely melted, adding a zinc ingot, and Mg-5Zr master alloy and Mg-10Re rare earth master alloy blocks and stirring to obtain a magnesium alloy melt with uniform components; subjecting the melt to standing still, removing the smelting covering agent on the surface of a molten pool, heating the melt to 730-750° C., adding a magnesium alloy refining agent, and fully stirring the mixture for refining, and then subjecting the mixture to standing still and cooling to 680-700° C. to prepare for casting; and (3) casting: casting the magnesium alloy melt cooled to 680-700° C. into a cast rod crystallizer, and solidifying the magnesium alloy to form a magnesium alloy bar stock.

7. A preparation method of a magnesium alloy rim, wherein with the magnesium alloy section bar prepared in claim 5 as a raw material, the method comprises the following steps: (1) sawing and coiling the magnesium alloy section bar, and then cutting the excess material near a rim joint; (2) inserting a rim lining connecting piece into the magnesium alloy section bar at the rim joint and pressing the rim lining connecting piece into the rim joint completely, so that a rim connector is pressed and connected; (3) drilling holes in both sides of the rim joint, wherein the holes go deep into the rim lining connecting piece from the inner side of a rim on which a tire is mounted, and welding at the hole forming positions to fix a rim inner lining and the rim; (4) deburring and carrying out heat treatment to obtain the magnesium alloy rim.

8. The preparation method of a magnesium alloy rim according to claim 7, wherein in step (3), the rim lining and the rim are fixed by argon arc welding with a welding wire.

9. The preparation method of a magnesium alloy rim according to claim 7, wherein in step (4), heat treatment is heating the deburred rim to 200° C. and keeping the temperature for 1-2 hours.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0022] FIG. 1 is a cross-sectional view of a magnesium alloy section bar used as a bicycle rim prepared by the present invention;

[0023] FIG. 2 is a schematic diagram of a coiling process in a preparation method of a magnesium alloy rim of the present invention;

[0024] FIG. 3 is a schematic diagram of a cutting process in the preparation method of the magnesium alloy rim of the present invention;

[0025] FIG. 4 is a schematic diagram of an inserting process in the preparation method of the magnesium alloy rim of the present invention; and

[0026] FIG. 5 is a schematic structural diagram of a joint of a prepared magnesium alloy rim.

DETAILED DESCRIPTION

[0027] The technical scheme of the present invention will be further described below in conjunction with the drawings.

Example 1 Preparation of a Magnesium Alloy Section Bar

[0028] (1) Material Preparation

[0029] Magnesium alloy components include 5.5% of Zn, 0.3% of Zr, 0.5% of yttrium-rich mixed rare earth and the balance of Mg, wherein the yttrium-rich mixed rare earth includes 27.2% of Y, 18.1% of Nd, 14.6% of Gd, 13.4% of Dy, 11.8% of La, 7.1% of Ce, 4.5% of Pr, 2.3% of Ho and 1.1% of Er.

[0030] Mg and Zn are added in the form of a magnesium ingot and a zinc ingot, the magnesium ingot and the zinc ingot are pressed into small pieces, Zr is added in the form of Mg-5Zr master alloy, and the yttrium-rich mixed rare earth is added in the form of Mg-10Re rare earth master alloy.

[0031] (2) Smelting

[0032] The prepared magnesium ingot charged into a crucible furnace, the upper surface of the magnesium ingot is covered with a layer of a magnesium alloy smelting covering agent, and the furnace charge is heated to 720° C.; after the magnesium ingot is completely melted, the zinc ingot, and Mg-5Zr master alloy and Mg-10Re rare earth master alloy block are added, and after the components are melt, a magnesium alloy melt is fully stirred with a stirrer to make components of the magnesium alloy melt uniform; the melt is subjected to standing still for 15 minutes, the covering agent on the surface of a molten pool is removed by a slag spoon, after the melt is heated to 740° C., a magnesium alloy refining agent is added, the magnesium alloy melt is fully stirred with a stirrer, the magnesium alloy is refined to remove gas and debris in the magnesium alloy melt, and then the magnesium alloy melt is subjected to standing still and cooled to 700° C. to prepare for casting.

[0033] (3) Casting: the magnesium alloy melt cooled to 700° C. is cast into a magnesium alloy semi-continuous cast rod crystallizer of a specific specification, and the magnesium alloy can be solidified sequentially by controlling the casting speed, the crystallizer withdrawal speed and the cooling water flow rate to finally form a magnesium alloy semi-continuous cast rod with the length of 10-12 meters.

[0034] (4) The magnesium alloy cast rod and a bicycle rim section bar mold are put into a resistance heating furnace for heating to 300° C., and then the magnesium alloy bar stock is taken out from the heating furnace and put into an extruder preheated to 320° C. in advance for rim section bar extrusion production to obtain a magnesium alloy section bar 1 with the cross section shown as FIG. 1.

Example 2 Preparation of a Magnesium Alloy Section Bar

[0035] (1) Material Preparation

[0036] Magnesium alloy components include 6.0% of Zn, 0.6% of Zr, 2.0% of yttrium-rich mixed rare earth and the balance of Mg, wherein the yttrium-rich mixed rare earth includes 26.1% of Y, 16.2% of Nd, 15.8% of Gd, 14.7% of Dy, 11.5% of La, 6.6% of Ce, 4.3% of Pr, 3.2% of Ho and 1.6% of Er.

[0037] Mg and Zn are added in the form of a magnesium ingot and a zinc ingot, the magnesium ingot and the zinc ingot are pressed into small pieces, Zr is added in the form of Mg-5Zr master alloy, and the yttrium-rich mixed rare earth is added in the form of Mg-10Re rare earth master alloy.

[0038] (2) Smelting

[0039] The prepared magnesium ingot is charged into a crucible furnace, the upper surface of the magnesium ingot is covered with a layer of a magnesium alloy smelting covering agent, and the furnace charge is heated to 730° C.; after the magnesium ingot is completely melted, the zinc ingot, and Mg-5Zr master alloy and Mg-10Re rare earth master alloy blocks are added, and after the components are melt, a magnesium alloy melt is fully stirred with a stirrer to make components of the magnesium alloy melt uniform; the melt is subjected to standing still for 15 minutes, the covering agent on the surface of a molten pool is removed by a slag spoon, after the melt is heated to 750° C., a magnesium alloy refining agent is added, the magnesium alloy melt is fully stirred with a stirrer, the magnesium alloy is refined to remove gas and debris in the magnesium alloy melt, and then the magnesium alloy melt is subjected to standing still and cooled to 680° C. to prepare for casting.

[0040] (3) Casting: the magnesium alloy melt cooled to 680° C. is cast into a magnesium alloy semi-continuous cast rod crystallizer of a specific specification, and the magnesium alloy can be solidified sequentially by controlling the casting speed, the crystallizer withdrawal speed and the cooling speed to finally form a magnesium alloy semi-continuous cast rod with the length of 10-12 meters.

[0041] (4) The magnesium alloy cast rod and a bicycle rim section bar mold are put into a resistance heating furnace for heating to 400° C., and then the magnesium alloy bar stock is taken out from the heating furnace and put into an extruder preheated to 380° C. in advance for rim section bar extrusion production to obtain a magnesium alloy section bar which meets the requirements for rim mechanical properties.

Example 3 Preparation of a Magnesium Alloy Section Bar

[0042] (1) Material Preparation

[0043] Magnesium alloy components include 5.8% of Zn, 0.5% of Zr, 1.2% of yttrium-rich mixed rare earth and the balance of Mg, wherein the yttrium-rich mixed rare earth includes 27.9% of Y, 17.8% of Nd, 14.7% of Gd, 13.3% of Dy, 10.6% of La, 6.1% of Ce, 4.2% of Pr, 3.1% of Ho and 2.3% of Er.

[0044] Mg and Zn are added in the form of a magnesium ingot and a zinc ingot, the magnesium ingot and the zinc ingot are pressed into small pieces, Zr is added in the form of Mg-5Zr master alloy, and the yttrium-rich mixed rare earth is added in the form of Mg-10Re rare earth master alloy.

[0045] (2) Smelting

[0046] The prepared magnesium ingot is charged into a resistance crucible furnace, the upper surface of the magnesium ingot is covered with a layer of a magnesium alloy smelting covering agent, and the furnace charge is heated to 730° C. by energizing; after the magnesium ingot is completely melted, the zinc ingot, and Mg-5Zr master alloy and Mg-10Re rare earth master alloy blocks are added, and after the components are melt, a magnesium alloy melt is fully stirred with a stirrer to make components of the magnesium alloy melt uniform; the melt is subjected to standing still for 15 minutes, the covering agent on the surface of a molten pool is removed by a slag spoon, the melt is heated to 730° C., a magnesium alloy refining agent is added, the magnesium alloy melt is fully stirred with a stirrer, the magnesium alloy is refined to remove gas and debris in the magnesium alloy melt, and then the magnesium alloy melt is subjected to standing still and cooled to 690° C. to prepare for casting.

[0047] (3) Casting: the magnesium alloy melt cooled to 690° C. is cast into a magnesium alloy semi-continuous cast rod crystallizer of a specific specification, and the magnesium alloy can be solidified sequentially by controlling the casting speed, the crystallizer withdrawal speed and the cooling speed to form a magnesium alloy semi-continuous cast rod with the length of 10-12 meters at last.

[0048] (4) The magnesium alloy cast rod and a bicycle rim section bar mold are put into a resistance heating furnace for heating to 350° C., and then the magnesium alloy bar stock is taken out from the heating furnace and put into an extruder preheated to 360° C. in advance for rim section bar extrusion production to obtain a magnesium alloy section bar which meets the requirements for rim mechanical properties.

Example 4 Preparation of a Magnesium Alloy Section Bar

[0049] (1) Material Preparation

[0050] Magnesium alloy components include 5.8% of Zn, 0.5% of Zr, 1.5% of yttrium-rich mixed rare earth and the balance of Mg, wherein the yttrium-rich mixed rare earth includes 29.8% of Y, 19.7% of Nd, 12.1% of Gd, 10.1% of Dy, 8.0% of La, 9.8% of Ce, 3.1% of Pr, 4.6% of Ho and 2.8% of Er.

[0051] Mg and Zn are added in the form of a magnesium ingot and a zinc ingot, the magnesium ingot and the zinc ingot are pressed into small pieces, Zr is added in the form of Mg-5Zr master alloy, and the yttrium-rich mixed rare earth is added in the form of Mg-10Re rare earth master alloy.

[0052] (2) Smelting

[0053] The prepared magnesium ingot is charged into a resistance crucible furnace, the upper surface of the magnesium ingot is covered with a layer of a magnesium alloy smelting covering agent, and the furnace charge is heated to 700° C. by energizing; after the magnesium ingot is completely melted, the zinc ingot, and Mg-5Zr master alloy and Mg-10Re rare earth master alloy blocks are added, and after the components are melt, a magnesium alloy melt is fully stirred with a stirrer to make components of the magnesium alloy melt uniform; the melt is subjected to standing still for 15 minutes, the covering agent on the surface of a molten pool is removed by a slag spoon, the melt is heated to 740° C., a magnesium alloy refining agent is added, the magnesium alloy melt is fully stirred with a stirrer, the magnesium alloy is refined to remove gas and debris in the magnesium alloy melt, and then the magnesium alloy melt is subjected to standing still and cooled to 690° C. to prepare for casting.

[0054] (3) Casting: the magnesium alloy melt cooled to 690° C. is cast into a magnesium alloy semi-continuous cast rod crystallizer of a specific specification, and the magnesium alloy can be solidified sequentially by controlling the casting speed, the crystallizer withdrawal speed and the cooling speed to form a magnesium alloy semi-continuous cast rod with the length of 10-12 meters at last.

[0055] (4) The magnesium alloy cast rod and a bicycle rim section bar mold are put into a resistance heating furnace for heating to 300° C., and then the magnesium alloy bar stock is taken out from the heating furnace and put into an extruder preheated to 300° C. in advance for rim section bar extrusion production to obtain a magnesium alloy section bar which meets the requirements for rim mechanical properties.

[0056] The mechanical properties of the magnesium alloy section bars prepared in Examples 1 to 4 are tested, and the results obtained are shown as Table 1:

TABLE-US-00001 TABLE 1 Mechanical properties of the magnesium alloy section bars prepared in Examples 1 to 3 Example 1 Example 2 Example 3 Example 4 Tensile strength 405 MPa 397 MPa 393 MPa 409 MPa Yield strength 296 MPa 287 MPa 295 MPa 302 MPa Elongation 12.9% 18.7% 16.8% 15.2%

Example 5 Preparation of a Magnesium Alloy Rim

[0057] With the magnesium alloy section bar prepared in Example 3 as a raw material, a magnesium alloy rim is prepared, and the steps are as follows:

[0058] {circle around (1)} Blanking: the required length of the magnesium alloy section bar is determined according to the diameter of a rim, and sawing is carried out;

[0059] {circle around (2)} Coiling: as shown in FIG. 2, the magnesium alloy section bar 1 is put on a track of a coiling device, and device parameters are adjusted for coiling according to the diameter of the rim;

[0060] {circle around (3)} Cutting: the coiled rim 2 is put on a special cutting device 4, and the excess material near a rim joint 3 is cut, as shown in FIG. 3;

[0061] {circle around (4)} Inserting: as shown in FIG. 4, a rim lining connecting piece 5 is inserted into the magnesium alloy section bar at the rim joint 3, then the rim is put on a special inserting machine, and the rim lining connecting piece 5 is fully pressed into the rim joint 3 by using the inserting machine to make the inside of a connector pressed and connected;

[0062] {circle around (5)} Drilling: the connected rim is put on a rim drilling platform and fixed, and spoke holes are automatically drilled;

[0063] {circle around (6)} Welding: circular holes 6 with the diameter of 5 mm are drilled respectively in the parts 15 mm away from the both sides of the joint at the inner side of a rim on which a tire is mounted, then the rim lining connecting piece 5 and the rim 2 are fixed by argon arc welding with a welding wire, and the structure of the rim joint is shown as FIG. 5;

[0064] {circle around (7)} Deburring: after rim welding is completed, burrs and chamfers at the drilling parts and other parts are removed to complete rim processing; and

[0065] {circle around (8)} Heat treatment: the processed rim is put into a heat treatment furnace, heated to 200° C. and then taken out from the furnace after temperature keeping for 2 hours.

Comparative Example

[0066] With the magnesium alloy section bar prepared in Example 3 as a raw material, a magnesium alloy rim is prepared by using a conventional method in the prior art, and the steps are as follows:

[0067] {circle around (1)} Blanking: the required length of the magnesium alloy section bar is determined according to the diameter of a rim, and sawing is carried out;

[0068] {circle around (2)} Coiling: as shown in FIG. 2, the magnesium alloy section bar is put on a track of a coiling device, and device parameters are adjusted for coiling according to the diameter of the rim;

[0069] {circle around (3)} Cutting: the coiled rim is put on a special cutting device, and the excess material near a rim joint is cut, as shown in FIG. 3;

[0070] {circle around (4)} Inserting: as shown in FIG. 4, a rim lining connecting piece after gluing is inserted into the magnesium alloy section bar at the rim joint, then the rim is put on a special inserting machine, and the rim lining connecting piece is fully pressed into the rim joint by using the inserting machine to make the inside of a connector pressed and connected;

[0071] {circle around (5)} Deburring: after rim welding is completed, burrs and chamfers at the drilling parts and other parts are removed to complete rim processing; and

[0072] {circle around (6)} Heat treatment: the processed rim is put into a heat treatment furnace, heated to 200° C. and then taken out from the furnace after temperature keeping for 1-2 hours.

[0073] The bicycle rims prepared in Example 5 and Comparative Example are tested for rim compressive deformation, and the detection standard is that the compressive deformation of a rim under a load of 500 N for 2 minutes is lower than 1 mm; the test results are shown as Table 2, and it can be seen that the deformation of the bicycle rim prepared in Example 5 is lower than 1 mm, indicating that it meets the use requirements of bicycle rims; and the deformation of the bicycle rim prepared in Comparative Example is higher than 1 mm, and obviously, the compressive deformation of the rim exceeds the standard.

TABLE-US-00002 TABLE 2 Test results of compressive deformation of rims Example 5 Comparative Example Compressive deformation of rims 0.425 mm 2.351 mm Result judgment Qualified Unqualified