Patent Application
20240060159
The disclosure claims priority to Chinese patent application No. CN 202110040804.4 filed in Chinese Patent Office on Jan. 13, 2021, named “Mg—Al based magnesium alloy and tube preparation method and application thereof”, the entire content of which is incorporated here by reference.
The present disclosure relates to a Mg—Al based magnesium alloy, and a preparation method of a tube of the magnesium alloy, and an application of the magnesium alloy, and belongs to the technical field of alloy materials.
Magnesium alloys are by far the lightest metal structural material, their density is only ⅔ of that of aluminum and ¼ of that of steel, and they have high specific strength and specific stiffness. In addition, magnesium alloys also have many excellent properties such as good damping, cutting machinability and thermal conductivity, as well as easy recovering and regeneration, making their application fields increasingly expanded.
Magnesium alloys mainly include Mg—Al based and Mg—Zn—Zr based magnesium alloys, and Mg—Al based magnesium alloys have been widely used because of their lower preparation costs and simpler preparation methods. However, the traditional Mg—Al based alloys have poor elongation, and are prone to fracture when subjected to external impact deformation or cyclic loading. In addition, magnesium alloys are generally connected to each other by welding during application, and traditional Mg—Al based alloys have a large welding loss rate after welding, which not only causes a lot of waste of resources, but also affects the welding firmness and aesthetic appearance.
Objection of the disclosure: in view of the problems of the existing Mg—Al based magnesium alloys, the disclosure provides a Mg—Al based magnesium alloy with high elongation and low welding loss rate and provides a preparation method of a tube of the Mg—Al based magnesium alloy; in addition, an application of the Mg—Al based magnesium alloy in the fields of vehicle equipment and medical equipment is also provided.
The technical solution: the Mg—Al based magnesium alloy of the present disclosure includes, by weight percentage, 7.0-8.6% Al, 0.8-2.0% RE, 0.2-0.8% Mn, and a balance of Mg, and the magnesium alloy has an elongation of 15-22%.
Optionally, the elongation of the Mg—Al based magnesium alloy is 17-21.6%.
Optionally, the Mg—Al based magnesium alloy has a welding loss rate of less than 6%.
Optionally, the Mg—Al based magnesium alloy has a yield strength of 182-235 MPa and a tensile strength of 306-342 MPa.
Preferably, in the Mg—Al based magnesium alloy, the weight percentage of Al is 7.0-8.2%, the weight percentage of RE is 1.1-2.0%, and the weight percentage of Mn is 0.4-0.8%. The magnesium alloys with components within the above parameter range can achieve lower welding loss rate (less than 5.50%), higher elongation, and higher strength.
More preferably, in the Mg—Al based magnesium alloy, the weight percentage of Al is 7.8-8.2%, the weight percentage of RE is 1.3-1.9%, and the weight percentage of Mn is 0.5-0.8%; and in RE, the weight percentage of Y is 0.8-1.6%, and the mass percentage of Ce is 0-0.8%. In this case, the obtained magnesium alloy has an elongation of 17.4-21.6%, a welding loss rate of less than 5%, a yield strength of 220-235 MPa, and a tensile strength of 320-342 MPa.
Even more preferably, in the Mg—Al based magnesium alloy, the weight percentage of Al is 7.8-8.2%, the weight percentage of RE is 1.5-1.9%, and the weight percentage of Mn is 0.5-0.8%; and in RE, the weight percentage of Y is 0.8%, and the mass percentage of Ce is 0.5-0.8%. In this case, the obtained magnesium alloy has a welding loss rate of less than or equal to 4.3%.
Optionally, in the magnesium alloy above, RE includes at least one of La, Ce, Nd, Y, Gd, Ho, Dy, and Er. RE includes mainly Y and Ce, and other rare earth elements are in trace amounts.
The preparation method of a tube of the Mg—Al based magnesium alloy according to the present disclosure comprises steps of:
The application of the Mg—Al based magnesium alloy of the present disclosure is use of the Mg—Al based magnesium alloy in the fields of vehicle equipment and medical equipment.
Beneficial effects: compared with the prior art, the advantages of the present disclosure includes: the Mg—Al based magnesium alloy of the present disclosure has high elongation, and the elongation of the tube formed using the same can reach 15-22%, so that the magnesium alloy can withstand large plastic deformation. Meanwhile, this Mg—Al based magnesium alloy has a very low welding loss rate of less than 6%, which greatly reduces the strength loss of magnesium alloy profiles after welding, and ensures the strength of magnesium alloy profiles after welding. In addition, the Mg—Al based magnesium alloy of the present disclosure also has high strength, its yield strength reaches 182-232 MPa, and its tensile strength reaches 306-340 MPa.
The technical solutions of the present disclosure will be further described below with reference to the accompanying drawings and examples.
A Mg—Al based magnesium alloy of the present disclosure includes, by weight percentage, 7.0-8.6% Al, 0.8-2.0% RE, 0.2-0.8% Mn, and a balance of Mg.
Specifically, in the magnesium alloy of the present disclosure, RE (rare earth element) and Mn are added to a Mg—Al based alloy with components in a certain proportion, thereby improving the plasticity and strength of the magnesium alloy and reducing the welding loss rate of the alloy.
Addition of Mn allows removing the impurity element Fe introduced during semi-continuous casting, which is advantageous to welding performance and mechanical properties, thereby reducing the welding loss rate. Meanwhile, Mn does not form a compound in magnesium, and can be used as heterogeneous nucleation particles to refine grains. When the alloy is extruded into a tube, Mn promotes dynamic recrystallization, refines grains, and weakens texture, thereby improving strength and plasticity.
The addition of RE can refine the grain size of the magnesium alloy, improve the morphology of the β strengthening phase of the magnesium alloy, and enhance the strength and plasticity of the magnesium alloy. The strength of the magnesium alloy can be reflected by the yield strength and tensile strength. After the Mg—Al based magnesium alloy provided by the present disclosure is formed into a tube, the range of the yield strength of the tube is 182-235 MPa, and preferably the range of the yield strength of the tube is 220-235 MPa. Meanwhile, the tensile strength of the Mg—Al based magnesium alloy tube ranges from 306 to 342 MPa, preferably 320 to 340 MPa. The elongation has a direct correlation to the plasticity of the magnesium alloy. After the Mg—Al based magnesium alloy provided by the present disclosure is formed into a tube, the elongation of the tube can reach 15-22%, and preferably the elongation of the Mg—Al based magnesium alloy tube is 17-21.6%. A high elongation allows the magnesium alloy to withstand large plastic deformation and improves the application range of the magnesium alloy.
The welding strength loss rate is the strength loss rate of the welded sample compared to the original profile sample after the magnesium alloy profile is welded. The welding strength loss rate of the Mg—Al based magnesium alloy provided by the present disclosure is less than 6%, preferably, the welding strength loss rate is less than 5%, and more preferably, the welding strength loss rate is less than 4.3%. In the magnesium alloy provided by the examples of the present disclosure, due to the addition of RE element, Al-RE high-temperature stable phase is formed during high temperature welding, and the high-temperature stable phase is pinned at the grain boundary, which hinders the growth of magnesium alloy grains during the welding process. Furthermore, the RE element can greatly reduce/refine the size of the β strengthening phase in the magnesium alloy, and avoid the growth of the β strengthening phase in the high temperature welding process, thereby reducing the strength loss of the magnesium alloy profile after welding, and ensuring the strength of the magnesium alloy profile after welding.
Optionally, the range of the weight percentage of Al in the Mg—Al based magnesium alloy of the present disclosure is 7.0-8.6%, preferably the range of the weight percentage of Al in the Mg—Al based magnesium alloy is 7.0-8.2%, and more preferably, the range of the weight percentage of Al is 7.8-8.2%.
Specifically, when the weight percentage of Al in the Mg—Al based magnesium alloy is controlled within a certain range, the combination of Al and Mg elements has a second-phase strengthening effect, and during the formation process of the magnesium alloy, the β strengthening phase can achieve the optimum state (moderate volume fraction, morphology, and size), thereby improving the strength of magnesium alloys. Meanwhile, the Al element as a solid solution part in the magnesium matrix can play a role in solid solution strengthening and improving plasticity. When the weight percentage of Al in the Mg—Al based magnesium alloy is extremely high, for example, the weight percentage of Al in the Mg—Al based magnesium alloy is greater than 8.6%, due to the precipitation of the coarse eutectic β phase, on the one hand, after welding, the interface bonding ability between the precipitated phase and the matrix is weakened, and microscopic pores are easily formed at the interface between the matrix and the β phase, which increase the welding loss rate; and on the other hand, the coarse β phase may cause, in the course of service, stress concentration, advance occurrence of plastic instability and reduced elongation. When the weight percentage of Al in the magnesium alloy is extremely low, for example, less than 7%, the reduction of the Al element in the crystal is not conducive to improving the plasticity, and meanwhile, the amount of precipitated phase is less, and the degree of refinement of grains is reduced, causing the second phase strengthening effect not to be exhibited, which is not conducive to the improvement of the strength of the magnesium alloy. In addition, for the alloy containing less precipitated phase after welding, the grain growth is more obvious, thus causing the welding loss rate to increase.
Optionally, the range of the weight percentage of RE in the Mg—Al based magnesium alloy of the present disclosure is 0.8-2.0%, preferably, the range of the weight percentage of RE in the Mg—Al based magnesium alloy is 1.1-2.0%, and more preferably, the range of the weight percentage of RE is 1.3-1.9%. Specifically, after RE is added to the Mg—Al based magnesium alloy, since the RE element has a unique electronic arrangement structure and chemical characteristics, addition of an appropriate amount of rare earth elements to the magnesium alloy can enhance the interatomic bonding force, reduce the diffusion rate of magnesium atoms, increase the recrystallization temperature of the magnesium alloy, slow down the recrystallization growth rate, and significantly improve the formability and corrosion resistance of the magnesium alloy. Further, RE is generally distributed in the grain boundaries and can reduce the grain size of the magnesium alloy and improve coordination ability between the grains of the magnesium alloy. RE can also form a thermally stable p strengthening phase during the formation process of the magnesium alloy, which improves the strength and plasticity of the magnesium alloy.
RE may include at least one of La, Ce, Nd, Y, Gd, Ho, Dy, and Er. Specifically, the RE elements in the Mg—Al based magnesium alloy of the present disclosure are mainly Y and Ce. The weight percentage of Y ranges from 0.8% to 1.6%, and the weight percentage of Ce ranges from 0 to 0.8%.
In
Specifically, the casting process in S102 can be implemented by a semi-continuous casting process. With the semi-continuous process, due to rapid water cooling, the size of obtained grains is small, and the fine grains can improve both the strength and the elongation of the alloy. In S103, the first temperature ranges from 360° C. to 400° C., and the heat treatment time is 6-10 h. The heat treatment process before extrusion can increase the content of Al element in the matrix, increase the slip system, and improve the elongation of the alloy.
When preparing the Mg—Al based magnesium alloy tube, in step S102, the ingot is cast into a bar, that is, the liquid mixed metal is cast into a bar; and in step S104, the heat-treated bar is subjected to back extrusion forming to obtain a Mg—Al based magnesium alloy tube. The process parameters of back extrusion forming include extrusion temperature, extrusion ratio, and extrusion speed, among which the extrusion temperature ranges from 280° C. to 330° C., the extrusion ratio is 49:1, and the extrusion speed ranges 8 mm/s to 15 mm/s.
Taking the preparation of Mg—Al based magnesium alloy tubes as an example, the magnesium alloy provided by the present disclosure will be described in detail through the following specific examples and comparative examples. The magnesium alloy tubes obtained by the preparation method provided in the examples of the present disclosure have a large elongation and can withstand large plastic deformation, and the magnesium alloy tubes have a low welding loss rate, and these properties improve the application range of the magnesium alloy. Also, the magnesium alloy has higher yield strength and tensile strength.
A Mg—Al based magnesium alloy included: 7 g Al, 0.8 g Y, 0.5 g Mn, and 91.7 g Mg.
The Mg—Al based magnesium alloy was obtained by the following preparation method specifically including:
A Mg—Al based magnesium alloy included: 7.4 g Al, 0.8 g Y, 0.5 g Mn, and 91.3 g Mg.
The Mg—Al based magnesium alloy was obtained by the following preparation method specifically including:
A Mg—Al based magnesium alloy included: 7.8 g Al, 0.8 g Y, 0.5 g Mn, and 91.9 g Mg.
The Mg—Al based magnesium alloy was obtained by the following preparation method specifically including:
A Mg—Al based magnesium alloy included: 8.2 g Al, 0.8 g Y, 0.5 g Mn, and 90.5 g Mg.
The Mg—Al based magnesium alloy was obtained by the following preparation method specifically including:
A Mg—Al based magnesium alloy included: 8.6 g Al, 0.8 g Y, 0.5 g Mn, and 90.1 g Mg.
The Mg—Al based magnesium alloy was obtained by the following preparation method specifically including:
A Mg—Al based magnesium alloy included: 7.8 g Al, 1.2 g Y, 0.5 g Mn, and 90.5 g Mg.
The Mg—Al based magnesium alloy was obtained by the following preparation method specifically including:
A Mg—Al based magnesium alloy included: 7.8 g Al, 1.6 g Y, 0.5 g Mn, and 90.1 g Mg.
The Mg—Al based magnesium alloy was obtained by the following preparation method specifically including:
A Mg—Al based magnesium alloy included: 7.8 g Al, 0.8 g Y, 0.3 g Ce (RE 1.1%), 0.5 g Mn, and 90.6 g Mg.
The Mg—Al based magnesium alloy was obtained by the following preparation method specifically including:
A Mg—Al based magnesium alloy included: 7.8 g Al, 1.2 g Y, 0.3 g Ce (RE 1.5%), 0.5 g Mn, and 90.2 g Mg.
The Mg—Al based magnesium alloy was obtained by the following preparation method specifically including:
A Mg—Al based magnesium alloy included: 7.8 g Al, 0.8 g Y, 0.5 g Ce (RE 1.3%), 0.5 g Mn, and 90.4 g Mg.
The Mg—Al based magnesium alloy was obtained by the following preparation method specifically including:
A Mg—Al based magnesium alloy included: 7.8 g Al, 0.8 g Y, 0.8 g Ce (RE 1.6%), 0.5 g Mn, and 90.1 g Mg.
The Mg—Al based magnesium alloy was obtained by the following preparation method specifically including:
A Mg—Al based magnesium alloy included: 7.8 g Al, 0.8 g Y, 0.5 g Ce, 0.1 g La (RE 1.4%), 0.5 g Mn, and 90.3 g Mg.
The Mg—Al based magnesium alloy was obtained by the following preparation method specifically including:
A Mg—Al based magnesium alloy included: 7.8 g Al, 0.8 g Y, 0.5 g Ce, 0.1 g La, 0.1 g Nd (RE 1.5%), 0.5 g Mn, and 90.2 g Mg.
The Mg—Al based magnesium alloy was obtained by the following preparation method specifically including:
A Mg—Al based magnesium alloy included: 7.8 g Al, 0.8 g Y, 0.5 g Ce, 0.1 g La, 0.1 g Nd, 0.1 g Gd (RE 1.6%), 0.5 g Mn, and 90.1 g Mg.
The Mg—Al based magnesium alloy was obtained by the following preparation method specifically including:
A Mg—Al based magnesium alloy included: 7.8 g Al, 0.8 g Y, 0.5 g Ce, 0.1 g La, 0.1 g Nd, 0.1 g Gd, 0.1 Ho (RE 1.7%), 0.5 g Mn, and 90.1 g Mg.
The Mg—Al based magnesium alloy was obtained by the following preparation method specifically including:
A Mg—Al based magnesium alloy included: 7.8 g Al, 0.8 g Y, 0.5 g Ce, 0.1 g La, 0.1 g Nd, 0.1 g Gd, 0.1 Ho, 0.1 Dy (RE 1.8%), 0.5 g Mn, and 90.0 g Mg.
The Mg—Al based magnesium alloy was obtained by the following preparation method specifically including:
A Mg—Al based magnesium alloy included: 7.8 g Al, 0.8 g Y, 0.5 g Ce, 0.1 g La, 0.1 g Nd, 0.1 g Gd, 0.1 Ho, 0.1 Dy, 0.1 Er (RE 1.9%), 0.5 g Mn, and 89.9 g Mg.
The Mg—Al based magnesium alloy was obtained by the following preparation method specifically including:
A Mg—Al based magnesium alloy included: 8.0 g Al, 0.8 g Y, 0.5 g Ce (RE 1.3%), 0.5 g Mn, and 90.4 g Mg.
The Mg—Al based magnesium alloy was obtained by the following preparation method specifically including:
A Mg—Al based magnesium alloy included: 8.0 g Al, 0.8 g Y, 0.5 g Ce, 0.1 g La, 0.1 g Nd, 0.1 g Gd, 0.1 Ho, 0.1 Dy, 0.1 Er (RE 1.9%), 0.5 g Mn, and 89.6 g Mg.
The Mg—Al based magnesium alloy was obtained by the following preparation method specifically including:
A Mg—Al based magnesium alloy included: 8.2 g Al, 0.8 g Y, 0.5 g Ce, 0.1 g La, 0.1 g Nd, 0.1 g Gd (RE 1.6%), 0.5 g Mn, and 89.7 g Mg.
The Mg—Al based magnesium alloy was obtained by the following preparation method specifically including:
A Mg—Al based magnesium alloy included: 7.8 g Al, 0.8 g Y, 0.5 g Ce (RE 1.3%), 0.2 g Mn, and 90.7 g Mg.
The Mg—Al based magnesium alloy was obtained by the following preparation method specifically including:
A Mg—Al based magnesium alloy included: 7.8 g Al, 0.8 g Y, 0.5 g Ce (RE 1.3%), 0.4 g Mn, and 90.5 g Mg.
The Mg—Al based magnesium alloy was obtained by the following preparation method specifically including:
A Mg—Al based magnesium alloy included: 7.8 g Al, 0.8 g Y, 0.5 g Ce (RE 1.3%), 0.8 g Mn, and 90.1 g Mg.
The Mg—Al based magnesium alloy was obtained by the following preparation method specifically including:
A Mg—Al based magnesium alloy included: 6.5 g Al, 0.8 g Y, 0.5 g Mn, and 92.2 g Mg.
The Mg—Al based magnesium alloy was obtained by the following preparation method specifically including:
A Mg—Al based magnesium alloy included: 9.6 g Al, 0.8 g Y, 0.5 g Mn, and 89.1 g Mg.
The Mg—Al based magnesium alloy was obtained by the following preparation method specifically including:
A Mg—Al based magnesium alloy included: 7 g Al, 0.5 g Y, 0.5 g Mn, and 92.0 g Mg.
The Mg—Al based magnesium alloy was obtained by the following preparation method specifically including:
A Mg—Al based magnesium alloy included: 7 g Al, 2.3 g Y, 0.5 g Mn, and 90.2 g Mg.
The Mg—Al based magnesium alloy was obtained by the following preparation method specifically including:
A Mg—Al based magnesium alloy included: 7 g Al, 0.8 g Y, and 92.2 g Mg.
The Mg—Al based magnesium alloy was obtained by the following preparation method specifically including:
It can be seen from Table 1 that the yield strengths of the magnesium alloy tubes of Examples 1-23 can all reach 182 MPa or greater, and the yield strength of the magnesium alloy tube of Example 19 reached 235 MPa; the tensile strengths of them can all reach 306 MPa or greater, and the tensile strength of the magnesium alloy tube of Example 19 reached 342 Mpa; the elongations of them were all greater than 15%, and the elongation of the magnesium alloy tube of Example 17 reached 21.6%; and the welding loss rates of the magnesium alloy tubes of Examples 1-23 were all less than 6%, and the welding loss rates of the magnesium alloy tubes of Examples 15-17, Examples 19-20, and Example 23 were less than or equal to 4%, and can be as low as 3.5%.
Comparing Example 1 with Comparative Examples 1 and 2, the magnesium alloy in Comparative Example 1, because of the low content of Al added, has low yield strength and tensile strength, which are as low as 165 Mpa and 287 Mpa respectively, and an increased welding loss rate; and the magnesium alloy in Comparative Example 2, because of the excessively high content of Al added, has deteriorated plasticity, and an elongation decreased to 12.7%, and meanwhile, the welding loss rate increases significantly to 7.3%.
Comparing Example 1 with Comparative Examples 3 and 4, the magnesium alloy in Comparative Example 3, because of the low content of RE added, has low yield strength and tensile strength, poor plasticity, and an elongation of only 13.9%, and meanwhile, the welding loss rate increases; and for the magnesium alloy in Comparative Example 4, in which the content of RE added is too high, although the yield strength and tensile strength of the magnesium alloy are improved, the plasticity is significantly deteriorated, the elongation is only 12.8%, and the welding loss rate also increases.
Comparing Example 1 with Comparative Example 5, in Comparative Example 5, since Mn was not added, the overall performance of the magnesium alloy decreases, where the elongation is significantly reduced, and the welding loss rate is significantly increased to over 6%.
The Mg—Al based magnesium alloy of the present disclosure can be applied to the fields of vehicle equipment and medical equipment. For example, the Mg—Al based magnesium alloy is formed into a bar, and a plurality of magnesium alloy bars can be used, after welded, as a load-bearing member or support member for equipment such as a wheelchair, a stretcher, a bicycle, a mountain bike. The Mg—Al based magnesium alloy can reduce the weight of the equipment above while ensuring the strength and stability of the equipment above.
| Number | Date | Country | Kind |
|---|---|---|---|
| 202110040801.4 | Jan 2021 | CN | national |
| Filing Document | Filing Date | Country | Kind |
|---|---|---|---|
| PCT/CN2022/071812 | 1/13/2022 | WO |
