WO2023087517A1

WO2023087517A1 - Aluminum alloy for casting motor rotor in new energy vehicle and preparation method therefor

Info

Publication number: WO2023087517A1
Application number: PCT/CN2022/070557
Authority: WO
Inventors: 赵培振; 郑金宇; 郑世育; 郑广会
Original assignee: 山东博源精密机械有限公司
Priority date: 2021-11-19
Filing date: 2022-01-06
Publication date: 2023-05-25
Also published as: CN114318090A; MX2024006085A; EP4435125A1; CN114318090B

Abstract

The present application relates to the technical field of motors of new energy vehicles, and discloses an aluminum alloy for casting a motor rotor in a new energy vehicle and a preparation method therefor. The aluminum alloy comprises 0.05 wt%-0.06 wt% of titanium, 0.04 wt%-0.06 wt% of boron, 0.15 wt%-0.5 wt% of silicon, 0.01 wt%-0.08 wt% of iron, 0.5 wt%-0.7 wt% of copper, 0.3 wt%-0.5 wt% of magnesium, 0.01 wt%-0.2 wt% of zinc, 0.02 wt%-0.12 wt% of manganese, and the balance of aluminum. By adding new elements and adjusting the ratio of the elements, the strength of the cast aluminum alloy is enhanced, and meanwhile, the excellent conductivity can also be kept.

Description

A new energy automobile motor rotor cast aluminum alloy and preparation method thereof

technical field

The application relates to a cast aluminum alloy for a new energy automobile motor rotor and a preparation method thereof, belonging to the technical field of new energy automobile motors.

This application claims the priority of the Chinese patent application with the application number 202111400150.8 and the title of the invention "A New Energy Automobile Motor Rotor Casting Aluminum Alloy and Its Preparation Method" submitted to the China Patent Office on November 19, 2021, the entire content of which Incorporated in this application by reference.

Background technique

With the intensification of world energy problems and environmental pollution problems, the development of new energy vehicles has gradually become the mainstream of modern car companies, and the motor rotors in new energy vehicles are generally cast with pure aluminum because aluminum has excellent electrical and thermal conductivity and low density. , meet the requirements of lightweight. With the rapid development of new energy vehicles, the requirements for motor rotors are getting higher and higher. For example, cast aluminum alloys must have high strength, high elongation, and good electrical conductivity. However, the update iteration speed of requirements for parameters such as strength is very fast. Fast, a year or even half a year to carry out technological innovation to meet the latest standards.

In the traditional technology, the crystal core is mainly increased by adding titanium boron, which improves the strength of the alloy. Iron, copper, magnesium and zinc have the effect of solid solution strengthening. However, parameters such as strength and elongation of aluminum alloys prepared by adding AlTiB additives still cannot meet the current needs. In order to minimize production and R&D costs, process adjustments are generally minimized, but in formula adjustments, the strength is often improved. However, parameters such as elongation and electrical conductivity are sacrificed, and it is difficult to improve the performance of all aspects simultaneously and are all within a good range.

Contents of the invention

In order to solve the above problems, a new energy automobile motor rotor casting aluminum alloy and its preparation method are provided. By adding new elements and adjusting the ratio of each element, the strength of the cast aluminum alloy can be significantly improved while maintaining excellent conductivity.

According to one aspect of the present application, a new energy automobile motor rotor cast aluminum alloy is provided, including titanium 0.05wt%-0.06wt%, boron 0.04wt%-0.06wt%, silicon 0.15wt%-0.5wt%, iron 0.01 wt%-0.08wt%, copper 0.5wt%-0.7wt%, magnesium 0.3wt%-0.5wt%, zinc 0.01wt%-0.2wt%, manganese 0.02wt%-0.12wt%, and the rest is aluminum.

Optionally, the aluminum alloy has a tensile strength of 80MPa-95MPa.

Optionally, the tensile strength of the aluminum alloy is 85MPa-95MPa.

Optionally, the yield strength of the aluminum alloy is 60MPa-80MPa.

Optionally, the elongation of the aluminum alloy is 45%-55%.

Optionally, the aluminum alloy has an electrical conductivity of 30MS/m-33MS/m.

Optionally, titanium 0.05wt%-0.06wt%, boron 0.04wt%-0.06wt%, silicon 0.15wt%-0.5wt%, iron 0.01wt%-0.08wt%, copper 0.5wt%-0.7wt%, Magnesium is 0.3wt%-0.5wt%, zinc is 0.01wt%-0.2wt%, manganese is 0.02wt%-0.12wt%, and the rest is composed of aluminum.

Optionally, the aluminum is high-purity aluminum, and high-purity aluminum is pure aluminum with a purity greater than 99.8%. The 0.2% unavoidable impurities in high-purity aluminum will not affect the technical effect of this application.

According to another aspect of the present application, there is provided a method for preparing the cast aluminum alloy of the motor rotor, comprising the following steps: (1) melting the aluminum ingot, adding various element components, and stirring evenly;

(2) The rotor cavity is preheated and centrifugally cast to obtain cast aluminum alloy for the motor rotor.

Optionally, the temperature in step (1) is 700-760°C, and the preheating temperature in step (2) is 680-720°C.

The beneficial effects of this application include but are not limited to:

1. According to the cast aluminum alloy of the motor rotor of the present application, titanium and boron can strengthen the crystalline core and refine the crystal grains, but if excessive titanium and boron are added, the second phase formed by the two will increase, and there will be too much migration Focusing will significantly reduce the electrical conductivity. In this application, titanium is limited to 0.05wt%-0.06wt%, and boron is limited to 0.04wt%-0.06wt%, which obviously increases the titanium content, and the final strength is significantly improved, but still Good electrical conductivity can be maintained because this application adds manganese element, which is limited to 0.02wt%-0.12wt%, while reducing the content of iron element, which is limited to 0.01wt%-0.08wt%. Manganese microalloy Melting can improve the strength, and change the microscopic phase of iron at the same time, so that the iron changes from the original needle-like shape to the block shape, and neutralizes the harmful effect of iron, thereby improving the elongation and electrical conductivity of the alloy at the same time.

2. According to the casting aluminum alloy of the motor rotor of this application, the magnesium content is limited to 0.3wt%-0.5wt%, which obviously increases the content of magnesium element, and the silicon content is limited to 0.15wt%-0.5wt%, which increases the silicon content and improves the casting performance and corrosion resistance, reduce the tendency of welding cracks, and also make a part of magnesium play a role of solid solution strengthening, and another part of magnesium can form new heterogeneous crystal nuclei with high content of silicon, forming Mg ₂ Si phase, which is conducive to fine crystallization to further increase the tensile strength and yield strength.

3. According to the cast aluminum alloy of the motor rotor of the present application, copper is also limited to 0.5wt%-0.7wt%, which significantly increases the copper content and enhances the precipitation strengthening effect. High content of copper and aluminum can form more θ-CuAl ₂ Precipitation strengthening phase, excess magnesium and excess copper can also form a part of S-CuMgAl ₂ precipitation strengthening phase with better strengthening, and at the same time improve the dispersion of each precipitation phase, and eliminate coarse manganese-containing brittle phases and grain boundary network brittle phases , reduce the parking effect, thereby improving the strength of the alloy.

4. According to this application, for the cast aluminum alloy of the motor rotor, the electrical conductivity requirement must reach 30MS/m or more to meet the demand, but the tensile strength of the motor rotor aluminum alloy of the existing manufacturers needs to reach at least 70MPa or more, 80MPa or higher according to different product grades. As mentioned above, the present application significantly improves the strength and other mechanical performance parameters of the aluminum alloy of the motor rotor while slightly reducing the electrical conductivity to meet the requirements.

Detailed ways

The present application is described in detail below in conjunction with the examples, but the present application is not limited to these examples.

Unless otherwise specified, the raw materials in the examples of the present application are all purchased through commercial channels, the preparation method adopts the existing centrifugal casting and smelting process, and other undisclosed parameters such as stirring speed are parameters used in the prior art.

Example 1 Preparation of aluminum alloy 1#

The composition of aluminum alloy 1# is: 0.05wt% of titanium, 0.05wt% of boron, 0.2wt% of silicon, 0.05wt% of iron, 0.6wt% of copper, 0.4wt% of magnesium, 0.1wt% of zinc, 0.08wt% of manganese, and the rest is High-purity aluminum, high-purity aluminum is pure aluminum with a purity greater than 99.8%.

The preparation method is as follows: (1) melting the aluminum ingot at 720°C, adding various element components, and stirring evenly;

(2) The rotor cavity is preheated to 700°C, and the motor rotor cast aluminum alloy 1# is manufactured by conventional centrifugal casting process.

The preparation of embodiment 2 aluminum alloy 2#

The composition of aluminum alloy 2# is: titanium 0.05wt%, boron 0.04wt%, silicon 0.15wt%, iron 0.01wt%, copper 0.5wt%, magnesium 0.3wt%, zinc 0.05wt%, manganese 0.02wt%, the rest is High-purity aluminum, high-purity aluminum is pure aluminum with a purity greater than 99.8%.

The preparation method is as follows: (1) melting the aluminum ingot at 700°C, adding various element components, and stirring evenly;

(2) The rotor cavity is preheated to 680°C, and the motor rotor cast aluminum alloy 2# is manufactured by conventional centrifugal casting process.

Example 3 Preparation of Aluminum Alloy 3#

The composition of aluminum alloy 3# is: titanium 0.06wt%, boron 0.06wt%, silicon 0.5wt%, iron 0.08wt%, copper 0.7wt%, magnesium 0.5wt%, zinc 0.2wt%, manganese 0.12wt%, the rest is High-purity aluminum, high-purity aluminum is pure aluminum with a purity greater than 99.8%.

The preparation method is as follows: (1) melting the aluminum ingot at 760°C, adding various element components, and stirring evenly;

(2) The rotor cavity is preheated to 720°C, and the motor rotor cast aluminum alloy 3# is manufactured by conventional centrifugal casting process.

Preparation of Comparative Example 1-6 Aluminum Alloy 4#-9#

The preparation methods of aluminum alloys 4#-9# are the same as that of aluminum alloy 1#, and the composition differences are shown in Table 1.

Table 1 Elemental composition of aluminum alloys 1#-9# (mass fraction wt%)

Embodiment 4 Aluminum alloy 1#-9# performance characterization

The motor rotor aluminum alloys 1#-9# are sampled on the end faces of the respective pairs. The size of the conductivity sample meets the requirements of GB/T12966-2008 and the conductivity test is carried out. The size standard of the mechanical performance test sample meets the ASTM E8 and is stretched. Performance analysis, mechanical properties and conductivity test results are shown in Table 2.

Table 2 Mechanical properties and electrical conductivity test results of motor rotor aluminum alloy 1#-9#

The results show that the motor rotor aluminum alloys 1#-3# prepared by using the element components defined in this application have excellent tensile strength and yield strength, the highest tensile strength can reach 95MPa, and the highest yield strength can reach 80MPa. It meets the requirements of the latest manufacturers with a tensile strength of 70MPa and above. At the same time, by adding a limited proportion of manganese, the elongation is also significantly improved, and the electrical conductivity can still meet the requirements of 30MS/m and above. The electrical conductivity is excellent, and it also limits copper and magnesium. The ratio of the elements finally sacrifices a small amount of electrical conductivity, so that the tensile strength, yield strength and elongation are significantly improved, which not only meets the higher demand of manufacturers for strength, but also ensures the excellent electrical conductivity of aluminum alloy.

Aluminum alloy 4# is a formula in the prior art, which is obviously different from the element types and proportions of this application. The final result shows that although its electrical conductivity is excellent, its mechanical properties such as strength cannot meet the latest requirements, and its tensile strength and yield strength are both lower. The content of manganese in aluminum alloy 5# is lower than the range defined in this application, and the final properties are all far lower than aluminum alloy 1#. The specific analysis is that the amount of manganese is too small to eliminate the harmful effects of iron; The content of manganese is higher than the range defined by the application, and the final elongation and electrical conductivity are better, but the strength is not enough. It is analyzed that the amount of manganese is more, and the coarse brittle phase (Mn, Fe) Al ₆ produced is more, and the final impact strength.

The iron content in aluminum alloy 7# exceeds the range defined in this application, which finally shows that its electrical conductivity is low, and parameters such as strength are not up to standard; the magnesium content in aluminum alloy 8# is lower than the range limited by this application, which finally shows that its strength is not enough , far lower than aluminum alloy 1#; the copper content in aluminum alloy 9# is lower than the range defined in this application, and finally shows that its parameters are not as good as aluminum alloy 1#, and the analysis shows that the copper content cannot generate more precipitation strengthening phases .

The foregoing descriptions are merely examples of the present application, and the protection scope of the present application is not limited by these specific examples, but is determined by the claims of the present application. For those skilled in the art, various modifications and changes may occur in this application. Any modifications, equivalent replacements, improvements, etc. made within the technical ideas and principles of this application shall be included within the scope of protection of this application.

Claims

A new energy automobile motor rotor cast aluminum alloy, characterized in that it includes 0.05wt%-0.06wt% of titanium, 0.04wt%-0.06wt% of boron, 0.15wt%-0.5wt% of silicon, and 0.01wt%-0.08wt% of iron %, copper 0.5wt%-0.7wt%, magnesium 0.3wt%-0.5wt%, zinc 0.01wt%-0.2wt%, manganese 0.02wt%-0.12wt%, and the rest is aluminum.
The cast aluminum alloy for the motor rotor according to claim 1, characterized in that the tensile strength of the aluminum alloy is 80MPa-95MPa.
The cast aluminum alloy for the motor rotor according to claim 2, wherein the tensile strength of the aluminum alloy is 85MPa-95MPa.
The cast aluminum alloy for motor rotor according to claim 1, characterized in that the yield strength of the aluminum alloy is 60MPa-80MPa.
The cast aluminum alloy for the motor rotor according to claim 1, wherein the elongation of the aluminum alloy is 45%-55%.
The cast aluminum alloy for motor rotor according to claim 1, characterized in that the electrical conductivity of the aluminum alloy is 30MS/m-33MS/m.
The cast aluminum alloy for motor rotor according to claim 1, characterized in that, titanium 0.05wt%-0.06wt%, boron 0.04wt%-0.06wt%, silicon 0.15wt%-0.5wt%, iron 0.01wt%- 0.08wt%, copper 0.5wt%-0.7wt%, magnesium 0.3wt%-0.5wt%, zinc 0.01wt%-0.2wt%, manganese 0.02wt%-0.12wt%, and the rest is composed of aluminum.
The cast aluminum alloy for the motor rotor according to claim 7, wherein the aluminum is high-purity aluminum, and the high-purity aluminum is pure aluminum with a purity greater than 99.8%.
A method for preparing a cast aluminum alloy for a motor rotor, characterized in that using the elemental components in claim 1 comprises the following steps:

(1) Melt the aluminum ingot, add each element component, and stir evenly;

(2) The rotor cavity is preheated and centrifugally cast to obtain cast aluminum alloy for the motor rotor.
The preparation method according to claim 9, characterized in that the temperature in step (1) is 700-760°C, and the preheating temperature in step (2) is 680-720°C.