Patent Grant
11781202
This application claims priority to Chinese Patent Application No. 202211112532.5, filed on Sep. 14, 2022, which is now Chinese Patent No. CN115181878B. The content of this application is incorporated herein by reference in its entirety.
The present invention relates to a new energy vehicle, and particularly to an aluminum alloy for a new energy vehicle integral die-cast part, a preparation method therefor and an application thereof.
A new energy vehicle lower body comprises a forward engine room, a battery compartment and an integral die-cast rear floor. The integral die-cast part generally has the characteristics of a large size, a thin wall thickness, a complex structure, etc., which puts forward higher requirements for the performance of aluminum alloy materials.
For traditional die-cast aluminum alloys for automobile, a heat treatment is a necessary process in order to ensure the mechanical properties of automobile components and parts; however, the heat treatment may cause the components and parts to have surface defects and dimensional deformation, leading to a reduced product yield and huge potential cost risks. Therefore, aluminum alloys suitable for integral die casting for new energy vehicles cannot be heat-treated. Under heat-free treatment conditions, the materials are required to have a high toughness as collision, fatigue, SPR connection, etc. should all be taken into consideration. At present, the farthest filling distance of an integral die-cast structural part reaches 2 m or more, which requires the material to have excellent casting performance to ensure excellent mold filling capacity. The use of recycled materials and sprue materials for automobile components and parts in the future requires the materials to have a relatively high tolerance to impurity elements, especially the element Fe. In summary, high-strength-and-toughness die casting aluminum alloys suitable for new energy vehicle integral die-cast parts necessarily have the characteristics of a high strength and toughness under heat-treatment-free condition, an excellent casting performance, and a relatively high tolerance to impurity elements. The traditional die casting aluminum alloys used for automobile components and parts can no longer meet the requirements thereof.
Patent application CN 114293058 A discloses a method for preparing a heat-treatment-free high-strength-and-toughness material suitable for cast parts with various wall thicknesses. The alloy comprises 5-8 wt % of Si, 0.30-0.50 wt % of Mg, 0.05-0.20 wt % of Ti, 0.01-0.03 wt % of Sr, Cu≤0.20 wt %, Fe≤0.20 wt %, Zn≤0.10 wt %, 0.5-0.8 wt % of Mn, 0.05-0.20 wt % of Nb, 0.01-0.03 wt % of B, 0.05-0.20 wt % of Cr, 0.06-0.15 wt % of La, and 0.04-0.10 wt % of Ce, with the sum of impurities being ≤0.2 wt %, wherein if the range of the content of the element Si is relatively low, it will have poor fluidity, be less suitable for a new energy vehicle integral large die-cast part, and easily cause less extension at the distal end for the portion of a large die-cast part most distal to a sprue; and the content of Fe in the patent is relatively low, which may affect, to a certain extent, the use of recycled materials and sprue materials for automobile components and parts to achieve a low-carbon goal.
Patent application CN 114438377 discloses a high-strength-and-toughness die casting aluminum alloy for a new energy vehicle and a preparation method therefor. The alloy comprises, in percentage by weight, the following elements: 8-10 wt % of Si, 0.05-0.5 wt % of Fe, Mn<1.0 wt %, 0.1-0.5 wt % of Mg, 0.1-1.0 wt % of Cu, Zn<1.0 wt %, 0.05-0.2 wt % of Ti, 0.005-0.05 wt % of Sr, La+Ce<0.5 wt %, Mo<0.1 wt %, and Sc<0.05 wt %, a sum of weight percentages of remaining impurities being controlled to be 0.5 wt % or less. In this invention, amorphous powders of Al—Ti—C—B, Al-20La+Ce, Al-20Mo and Al-3 Sc intermediate alloys are prepared by belt throwing combined with high-energy ball milling. The high-energy ball milling mixing method inevitably leads to a risk of impurity introduction. In addition, Al—Ti—C—B is used as a refiner, which inevitably impedes agglomeration of TiB2 particles and size growth and sinking of TiAl3 phase, which affect the life of the refiner. In addition, the aluminum alloy needs to be heat-treated at 200° C. for 4 h, such that the aluminum alloy has a tensile strength of more than 300 MPa, a yield strength of more than 120 MPa, and an elongation of 15-20%. An additional heat treatment is necessary, which leads to dimensional deformation, lower product yield and potential cost risk.
An object of the present invention is to provide an aluminum alloy for a new energy vehicle integral die-cast part, a preparation method therefor and an application thereof, in order to overcome the above defects existing in the prior art. The alloy has excellent casting performance and a relatively high tolerance to impurity elements, and can be used for preparing a low-carbon high-strength-and-toughness new energy vehicle lower body product without a heat treatment.
The object of the present invention can be achieved by the following technical solution: an aluminum alloy for a new energy vehicle integral die-cast part, the alloy comprising 7-9 wt % of Si, 0.05-0.25 wt % of Mg, Cu<0.5 wt %, Zn<0.5 wt %, 0.001-0.20 wt % of B, 0.05-0.2 wt % of Ti, 0.1-0.9 wt % of Mn, 0.05-0.3 wt % of Fe, 0.005-0.5 wt % of Sr, Ce<0.5 wt %, 0.01-0.1 wt % of Zr, 0.001-0.3 wt % of Mo, a sum of weight percentages of remaining impurities being controlled to be 1.0 wt % or less, and the balance being Al.
Furthermore, the Zr, Mn, Mo, Ti, B and Ce are added in a form of Al—Zr, Al—Mn, Al—Mo and Al—Ti—B—Ce amorphous intermediate alloys.
Furthermore, the amorphous intermediate alloys are obtained by means of laser evaporation to prepare Al—Zr, Al—Mn, Al—Mo, and Al—Ti—B—Ce.
In particular, the intermediate alloy amorphous powder is obtained by a way of following method: simultaneously placing Al—Zr, Al—Mn, Al—Mo and Al—Ti—B—Ce intermediate alloys as target materials in a closed chamber, evacuating the chamber to such a vacuum that the pressure is reduced to 10−5 Pa, introducing argon gas of 100-150 kPa, irradiating the four target materials respectively with a pulsed laser beam at a density of more than 100 kW/cm2, and finally collecting the materials to obtain mixed amorphous powders of Al—Zr, Al—Mn, Al—Mo and Al—Ti—B—Ce with specific compositional ratio. In this intermediate alloy amorphous powder, the elements Zr, Mn, Mo, Ti and Ce are uniformly dispersed, and the average particle size is 20-50 nm. During smelting, Zr, Mn, Mo, Ti and Ce can be uniformly dispersed in molten aluminum at a lower capacity temperature.
The present invention further provides a method for preparing an aluminum alloy for a new energy vehicle integral die-cast part, the method comprising the following steps:
The present invention further provides an application of an aluminum alloy for a new energy vehicle integral die-cast part, i.e., subjecting the aluminum alloy ingot to integral die casting molding to form a new energy vehicle lower body, which comprises the following steps:
the new energy vehicle lower body has a thickness of 1-3 mm, and a distal end of the new energy vehicle integral die-cast part has a tensile strength of 260-300 MPa, a yield strength of more than 110-130 MPa and an elongation of 10-14%.
Compared with the prior art, the present invention has the following advantages:
The following is a detailed description of the examples of the present invention. The examples are implemented on the premise of the technical solution of the present invention, and the detailed implementation method and specific operation process are given. However, the scope of protection of the present invention is not limited to the following examples.
An aluminum alloy for a new energy vehicle integral die-cast part comprised the following components in percentage as shown in Table 1, with the balance being aluminum and inevitable impurities.
The alloy material comprised 7-9 wt % of Si, 0.05-0.25 wt % of Mg, Cu<0.5 wt %, Zn<0.5 wt %, 0.001-0.20 wt % of B, 0.05-0.2 wt % of Ti, 0.1-0.9 wt % of Mn, 0.05-0.3 wt % of Fe, 0.005-0.5 wt % of Sr, Ce<0.5 wt %, 0.01-0.1 wt % of Zr, 0.001-0.3 wt % of Mo, a sum of weight percentages of remaining impurities being controlled to be 1.0 wt % or less, and the balance being Al.
Table 1 Table of the contents of the elements in the aluminum alloys of Examples 1-6 and the compositions of the materials prepared therefrom
The aluminum alloy ingot obtained in step 6) was re-melted at a temperature of 750° C., the temperature was maintained, a protective gas was introduced for isolation from the air during the maintaining of the temperature, the molten aluminum alloy was then injected into the die casting mold, and after die pressing, a 3 mm thick tensile sheet specimen was obtained.
The die casting mold was a mold temperature controller, and the temperature thereof was maintained at 250-350° C. in advance. In addition, the die casting machine was equipped with a heat-insulating barrel. During die casting, the barrel temperature was maintained at 200-250° C., an injection speed of 4 m/s was used, and the molten aluminum alloy ingot was rapidly cooled and molded under a pressure of 20-40 MPa. The tensile sheet specimen had a tensile strength of 260-300 MPa, a yield strength of 110-130 MPa and an elongation of 10-14%.
Table 2 Table of the mechanical properties of tensile sheets corresponding to Examples 1-6
The aluminum alloy ingot obtained by the above method was made into a product of new energy vehicle lower body. Taking the aluminum alloy ingot made in each example as an example, integral die casting molding was performed to make a new energy vehicle lower body. The method therefor comprised the following steps:
The performance of the obtained forward engine room product was tested, and the testing process and results were as follows: taking Examples 3 and 6 as examples, the mechanical properties of the new energy vehicle forward engine room products made according to the above method from the prepared aluminum alloy ingots at different positions proximal end and distal end of the sprue were as shown in Tables 3 and 4 below, wherein the numbers 1 #, 2 #, 3 #, 4 #, 5 # and 6 # were respectively numbers by which the mechanical properties of the new energy vehicle forward engine room products were tested at different positions from the inlet sprue as test points.
Table 3 Mechanical properties of the new energy vehicle forward engine room product made according to the above method from the aluminum alloy ingot made in Example 3 in different positions
Table 4 Mechanical properties of the new energy vehicle forward engine room product made according to the above method from the aluminum alloy ingot made in Example 6 in different positions
It could be seen from the above tables 3 and 4 that although the content of iron in the alloy of the present invention was relatively high, up to 0.3 wt % (the content of Fe in general automobile die casting alloy needed to be controlled within 0.15 wt %), the mechanical properties of the obtained alloy could still reach a tensile strength of 260-300 MPa, a yield strength of 110-130 MPa, an elongation of 10-14%, and the tolerance to the element Fe was improved. The new energy vehicle forward engine room products made of this alloy had, at different positions, a tensile strength of 260-300 MPa, a yield strength of 110-130 MPa and an elongation of 10-14%; moreover, the strengthening and toughening of the aluminum alloy as effective as in a heat treatment could be achieved, even without a specialized solid solution aging treatment; in addition, at the farthest distance distal to the inlet sprue, i.e. 2300 mm, the tensile strength was 260-300 MPa, the yield strength was 110-130 MPa, and the elongation was 10-14%. The material had excellent casting performance to ensure excellent mold filling capacity.
In the present invention, the tensile strength, yield strength and elongation were detected according to the national standard GB/T 228.1-2010.
| Number | Date | Country | Kind |
|---|---|---|---|
| 202211112532.5 | Sep 2022 | CN | national |
| Number | Name | Date | Kind |
|---|---|---|---|
| 6824737 | Koch | Nov 2004 | B2 |
| 7108042 | Koch | Sep 2006 | B2 |
| 20160271688 | Wuest et al. | Sep 2016 | A1 |
| 20190119791 | Wiesner | Apr 2019 | A1 |
| Number | Date | Country |
|---|---|---|
| 105986152 | Oct 2016 | CN |
| 106011847 | Oct 2016 | CN |
| 108359855 | Aug 2018 | CN |
| 110588099 | Dec 2019 | CN |
| 111607760 | Sep 2020 | CN |
| 114293058 | Apr 2022 | CN |
| 114438377 | May 2022 | CN |
| 114921696 | Aug 2022 | CN |
| 1443122 | Aug 2004 | EP |
| 1612286 | Jan 2006 | EP |
