A process for preparing aluminum alloy for new energy vehicle body

Abstract

The invention discloses a process for preparing an aluminum alloy for a new energy vehicle body, belonging to the technical field of aluminum alloys. The invention comprises the following steps: step S1, preparing ingredients according to the following weight percentages: Si: 0.60-0.70%, Fe: 0.10-0.20%, Cu: 0.20-0.30%, Mn: 0.35-0.45%, Mg: 0.60-0.75%, Ce: 0.45-0.50%, Y: 0.15-0.25%, with the remainder being aluminum and inevitable impurities; after smelting, degassing, refining, and deslagging are performed, casting is performed, and the ingot is homogenized; step S2, hot rolling the homogenized ingot and then cold rolling it to obtain an aluminum plate; step S3, solutionizing and heat-insulating the aluminum plate, then water quenching, and ageing and heat-insulating at 90°C; after naturally aging the plate, applying a lubricant on the surface and performing stamping forming, and performing artificial aging after stamping forming, thereby improving the mechanical properties of the aluminum alloy by adjusting the ratio of rare earth metals in the aluminum alloy formula.

Description

Technical Field

[0001] The present invention belongs to the technical field of aluminum alloys, and in particular relates to a process for preparing an aluminum alloy for a new energy vehicle body. Background Art

[0002] When deformed aluminum alloy sheets replace traditional steel, they can effectively reduce the weight of automobiles, achieve lightweighting of automobiles and reduce the energy loss of new energy vehicles. The performance requirements of aluminum alloys when used in automobile coverings are extremely high, so key links must be controlled during the production process. During the raw material production stage, the material composition needs to be designed, smelted and cast. After homogenization heat treatment, the material is prepared into sheets of different thickness specifications through cold and hot rolling processes. Finally, the microstructure and second phase are controlled through heat treatment to achieve products that meet production needs. Throughout the production process, reasonable composition design and the formulation of heat treatment processes are necessary prerequisites for ensuring high-quality sheets. However, compared with traditional mild steel, aluminum alloy sheets still have disadvantages during the forming process, such as large springback and easy cracking. Summary of the Invention

[0003] The purpose of the present invention is to provide a process for preparing aluminum alloy for new energy vehicle bodies, so as to solve the problem that alloy plates are prone to cracking during the forming process.

[0004] The purpose of the present invention can be achieved through the following technical solutions:

[0005] A process for preparing aluminum alloy for new energy vehicle body, comprising the following steps:

[0006] Step S1, preparing ingredients according to the following weight percentages: Si: 0.60-0.70%, Fe: 0.10-0.20%, Cu: 0.20-0.30%, Mn: 0.35-0.45%, Mg: 0.60-0.75%, Ce: 0.45-0.50%, Y: 0.15-0.25%, and the balance being aluminum and inevitable impurities; after smelting, degassing, refining, and deslagging are performed, casting is performed, and the ingot is homogenized; according to the weight ratio: Ce / Y is 2-3;

[0007] Cerium and yttrium, as rare earth metals, are added to aluminum alloys to improve and refine the aluminum alloy's structure. Through certain heat treatment processes, their structure and mechanical properties are enhanced, resulting in better formability. In the present invention, cerium and yttrium are selected to improve the mechanical properties of aluminum alloys. The addition of cerium can reduce the formation of pores. However, excessive cerium addition can introduce oxide inclusions and lower the aluminum melt temperature, significantly reducing the aluminum melt's viscosity and melt fluidity, hindering the removal of pores. In the present invention, the cerium content is adjusted to 0.45-0.50%.

[0008] Yttrium will form a new metal phase between the Al-Si based alloy, which can enhance the mechanical properties of the aluminum alloy. However, excessive yttrium will destroy the stability of the solid-liquid interface, causing segregation, which is not conducive to the growth of the alloy phase. In the present invention, the yttrium content is adjusted to 0.15-0.25%.

[0009] Step S2, hot rolling the homogenized ingot to a thickness of ≤6 mm, and then cold rolling it to the designed thickness of the plate to obtain an aluminum plate;

[0010] Step S3, solution-treating the aluminum plate, heat-insulating it, and then water quenching it, and heat-insulating it at 90°C; after naturally aging the plate, applying lubricant on the surface and stamping it, and then artificially aging it after stamping to obtain an aluminum alloy for new energy vehicle body.

[0011] Furthermore, degassing, refining and deslagging are carried out in an inert gas atmosphere or nitrogen.

[0012] Furthermore, the smelting temperature is 740-760°C.

[0013] Furthermore, the homogenization process in step S1 is as follows: heating at a rate of 10°C / min to 550-560°C, keeping the temperature for 18-20 hours, and quenching in cold water.

[0014] Furthermore, the hot rolling temperature in step S2 is 420-430° C., and the deformation amount of each cold rolling pass is 0.6-0.7 mm / pass.

[0015] Furthermore, the aging and heat preservation time in step S3 is ≥30 minutes; the natural aging is ≥15 days; and the artificial aging condition is 180-190° C. and heat preservation for 35-40 minutes.

[0016] Furthermore, the lubricant is prepared by the following steps:

[0017] Graphene oxide and deionized water were mixed and ultrasonically dispersed, 2,6-diaminopyridine was added, the temperature was set to 80-100°C, and the mixture was stirred for 30 minutes. The resulting mixture was dried to obtain modified graphene oxide; the amino groups on 2-6-diaminopyridine reacted with the carboxyl groups and epoxy groups on GO to undergo condensation reaction and ring-opening reaction to obtain modified graphene oxide;

[0018] Modified graphene oxide was added to anhydrous ethanol, and O,O-didodecyl dithiophosphate was added. The temperature was set to 60°C and the reaction was stirred for 30 minutes. After the reaction, the mixture was filtered and washed to obtain a solid filler. The graphene oxide was first modified with 2-6-diaminopyridine, and the introduced pyridine reacted with O,O-didodecyl dithiophosphate to obtain a solid filler. The O,O-didodecyl dithiophosphate can further enhance the exfoliation of the graphene oxide, improve the dispersion effect, and reduce the tendency of particles to agglomerate.

[0019] 20-30 parts of white oil, 10-12 parts of trihydroxypropane oleate, 4-5 parts of diisooctyl adipate, 2-2.5 parts of isobutylene sulfide and 3-5 parts of solid filler are weighed and mixed according to weight to obtain a lubricant.

[0020] Furthermore, the usage ratio of graphene oxide, deionized water and 2,6-diaminopyridine is 0.25 g:100 mL:0.1 g; the usage ratio of modified graphene oxide, O,O-didodecanedithiophosphate and anhydrous ethanol is 0.5 g:0.1 g:100 mL.

[0021] Beneficial effects of the present invention:

[0022] In the present invention, the mechanical properties of the aluminum alloy are improved by adjusting the ratio of rare earth metals in the aluminum alloy formula. Increasing the amount of a single rare earth metal is not conducive to improving the overall performance. Adjusting the Ce / Y ratio to 2-3 can improve its structure and mechanical properties, reduce the generation of pores, and strengthen the mechanical properties of the aluminum alloy, so that the prepared aluminum alloy has better formability and reduces cracking.

[0023] The present invention uses a lubricant during the stamping process, forming an oil film of a certain thickness between the contact surface of the die and the aluminum alloy during the stamping process, thereby improving the surface quality of the aluminum alloy after forming. The solid filler in the lubricant can form a layer and an adsorption film on the surface of the aluminum alloy, effectively isolating friction and providing friction reduction and anti-wear effects. The lubricant can also be deposited in recessed and worn areas on the aluminum alloy surface, repairing them and reducing the occurrence of cracks during processing. The lubricant in the present invention can reduce the forming force of the aluminum alloy sheet, reduce defects, improve the finish of the stamped parts, and extend the service life of the die. DETAILED DESCRIPTION

[0024] The following will be combined with the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the embodiments described are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making any creative efforts shall fall within the scope of protection of the present invention.

[0025] Example 1

[0026] This embodiment provides a lubricant, which is prepared by the following steps:

[0027] Graphene oxide and deionized water were mixed and ultrasonically dispersed, 2,6-diaminopyridine was added, the temperature was set to 80°C, and the mixture was stirred for 30 minutes. The obtained mixture was dried to obtain modified graphene oxide; the modified graphene oxide was added to anhydrous ethanol, O,O-didodecyl dithiophosphate was added, the temperature was set to 60°C, and the mixture was stirred for 30 minutes. After the reaction was completed, the mixture was filtered and washed to obtain a solid filler; the amount ratio of graphene oxide, deionized water and 2,6-diaminopyridine was 0.25g:100mL:0.1g; the amount ratio of modified graphene oxide, O,O-didodecyl dithiophosphate and anhydrous ethanol was 0.5g:0.1g:100mL;

[0028] 20 parts of white oil, 10 parts of trihydroxypropane oleate, 4 parts of diisooctyl adipate, 2 parts of isobutylene sulfide and 3 parts of solid filler were weighed and mixed according to weight to obtain a lubricant.

[0029] Example 2

[0030] This embodiment provides a lubricant, which is prepared by the following steps:

[0031] Graphene oxide and deionized water were mixed and ultrasonically dispersed, 2,6-diaminopyridine was added, the temperature was set at 100°C, and the mixture was stirred for 30 minutes. The obtained mixture was dried to obtain modified graphene oxide; the modified graphene oxide was added to anhydrous ethanol, O,O-didodecyl dithiophosphate was added, the temperature was set at 60°C, and the mixture was stirred for 30 minutes. After the reaction was completed, the mixture was filtered and washed to obtain a solid filler; the amount ratio of graphene oxide, deionized water and 2,6-diaminopyridine was 0.25g:100mL:0.1g; the amount ratio of modified graphene oxide, O,O-didodecyl dithiophosphate and anhydrous ethanol was 0.5g:0.1g:100mL;

[0032] 30 parts of white oil, 12 parts of trihydroxypropane oleate, 5 parts of diisooctyl adipate, 2.5 parts of isobutylene sulfide and 5 parts of solid filler were weighed and mixed according to weight to obtain a lubricant.

[0033] Comparative Example 1

[0034] Compared with Example 2, this comparative example is different in that the solid filler is replaced with modified graphene oxide and O,O-didodecyl dithiophosphate, the mass ratio of modified graphene oxide to O,O-didodecyl dithiophosphate is 5:1, and the other raw materials and preparation process remain the same as in Example 2.

[0035] Example 3

[0036] A process for preparing aluminum alloy for new energy vehicle body, comprising the following steps:

[0037] Step S1, preparing ingredients according to the following weight percentages: Si: 0.60%, Fe: 0.10%, Cu: 0.30%, Mn: 0.45%, Mg: 0.60%, Ce: 0.50%, Y: 0.25%, and the balance being aluminum and inevitable impurities; degassing, refining, and deslagging after smelting, and degassing, refining, and deslagging are performed under nitrogen; the smelting temperature is 740° C.; casting, and ingot homogenization treatment; the homogenization treatment process is as follows: heating rate of 10° C. / min, heating to 550° C., holding for 20 hours, and cold water quenching;

[0038] Step S2, hot rolling the homogenized ingot to a thickness of ≤6 mm, and then cold rolling it to the designed thickness of the plate to obtain an aluminum plate; the hot rolling temperature is 420° C., and the cold rolling deformation is 0.6 mm / pass;

[0039] Step S3, solution-treating the aluminum plate and then water-quenching it, and then aging and heat-insulating it at 90°C; after naturally aging the plate, apply the lubricant prepared in Example 1 on the surface and perform stamping, and after stamping, perform artificial aging treatment, and the aging and heat-insulating time is ≥30 minutes; natural aging is ≥15 days; artificial aging conditions are 180°C and heat-insulating for 40 minutes.

[0040] Example 4

[0041] A process for preparing aluminum alloy for new energy vehicle body, comprising the following steps:

[0042] Step S1, preparing ingredients according to the following weight percentages: Si: 0.65%, Fe: 0.15%, Cu: 0.25%, Mn: 0.40%, Mg: 0.65%, Ce: 0.50%, Y: 0.20%, and the balance being aluminum and inevitable impurities; degassing, refining, and deslagging after smelting, and degassing, refining, and deslagging are performed under nitrogen; the smelting temperature is 750° C.; casting, and ingot homogenization treatment; the homogenization treatment process is as follows: heating rate of 10° C. / min, heating to 555° C., holding for 19 hours, and cold water quenching;

[0043] Step S2, hot rolling the homogenized ingot to a thickness of ≤6 mm, and then cold rolling it to the designed thickness of the plate to obtain an aluminum plate; the hot rolling temperature is 425° C., and the cold rolling deformation is 0.6 mm / pass;

[0044] Step S3: Solution-treating the aluminum plate and then water-quenching it, followed by aging and heat preservation at 90°C; after naturally aging the plate, applying the lubricant prepared in Example 2 on the surface and performing stamping, and performing artificial aging after stamping, wherein the aging and heat preservation time is ≥30 min; natural aging is ≥15 days; and artificial aging conditions are 185°C and heat preservation for 40 min.

[0045] Example 5

[0046] A process for preparing aluminum alloy for new energy vehicle body, comprising the following steps:

[0047] Step S1, preparing ingredients according to the following weight percentages: Si: 0.70%, Fe: 0.20%, Cu: 0.20%, Mn: 0.35%, Mg: 0.75%, Ce: 0.45%, Y: 0.15%, and the balance being aluminum and inevitable impurities; degassing, refining, and deslagging after smelting, and degassing, refining, and deslagging are performed under nitrogen; the smelting temperature is 760° C.; casting, and ingot homogenization treatment; the homogenization treatment process is as follows: heating rate of 10° C. / min, heating to 560° C., holding for 18 hours, and cold water quenching;

[0048] Step S2, hot rolling the homogenized ingot to a thickness of ≤6 mm, and then cold rolling it to the designed thickness of the plate to obtain an aluminum plate; the hot rolling temperature is 430° C., and the cold rolling deformation is 0.6 mm / pass;

[0049] Step S3: Solution-treating the aluminum plate and then water-quenching it, followed by aging and heat preservation at 90°C; after naturally aging the plate, applying the lubricant prepared in Example 2 on the surface and performing stamping, and performing artificial aging after stamping, wherein the aging and heat preservation time is ≥30 min; natural aging is ≥15 days; and artificial aging conditions are 190°C and heat preservation for 35 min.

[0050] Comparative Example 2

[0051] Compared with Example 5, the addition amount of Y in this comparative example is 0.6%, and Ce is not added. The other raw materials and preparation process remain the same as those in Example 5.

[0052] Comparative Example 3

[0053] Compared with Example 5, this comparative example is different from Example 5 in that the lubricant is replaced with the sample prepared in Comparative Example 1, and the remaining raw materials and preparation process remain the same as those in Example 5.

[0054] Performance tests were performed on Examples 3 to 5 and Comparative Examples 2 to 3. According to GB / T 228.1-2010 "Tensile Test of Metallic Materials", the aluminum alloy sheet was processed parallel to the rolling direction (0°) into a national standard tensile specimen with a gauge length of 25 mm. The tensile test was performed at a speed of 2 mm / min. For each test, three standard samples were measured with a vernier caliper to measure the gauge length before and after the fracture to calculate the elongation after fracture, and the average value was taken. The results are shown in Table 1:

[0055] Table 1

[0056] project Example 3 Example 4 Example 5 Comparative Example 2 Comparative Example 3 Yield strength / MPa 339 341 342 319 338 Tensile strength / MPa 173 174 175 159 169 Elongation after break / % 15.9 15.9 15.8 13.7 15.2

[0057] As can be seen from Table 1, when the addition amount of Y is too much, it is not conducive to improving the strength of the aluminum alloy. Y and Ce are both rare earth metals, which have the effect of reducing the liquid-solid interfacial tension and the wetting angle, thereby stabilizing the solid-liquid interface. The two have the effect of synergistically improving the strength and elongation of the alloy. A single rare earth metal will lead to an excessive amount of Y element, which will have a negative impact on the mechanical properties of the aluminum alloy. In addition, the use of lubricants can compensate for surface defects, making the surface properties of the aluminum alloy more uniform, which is beneficial to improving the overall performance.

[0058] It should be noted that, in this document, relational terms such as first and second, etc., are used only to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any actual relationship or order between these entities or operations. Moreover, the terms "comprises," "comprising," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that includes a list of elements includes not only those elements but also other elements not explicitly listed, or elements inherent to such process, method, article, or apparatus.

[0059] While embodiments of the present invention have been shown and described, it will be appreciated by those skilled in the art that various changes, modifications, substitutions, and variations may be made to these embodiments without departing from the principles and spirit of the invention, and that the scope of the invention is defined by the appended claims and their equivalents.

Claims

1. A process for preparing aluminum alloy for new energy vehicle body, characterized in that: The steps include: Step S1, preparing ingredients according to the following weight percentages: Si: 0.60-0.70%, Fe: 0.10-0.20%, Cu: 0.20-0.30%, Mn: 0.35-0.45%, Mg: 0.60-0.75%, Ce: 0.45-0.50%, Y: 0.15-0.25%, and the balance being aluminum and inevitable impurities; after smelting, degassing, refining, and deslagging are performed, casting is performed, and the ingot is homogenized; according to the weight ratio: Ce / Y is 2-3; Step S2, hot rolling the homogenized ingot to a thickness of ≤6 mm, and then cold rolling to obtain an aluminum plate; Step S3, solutionizing and heat-insulating the aluminum plate, then water quenching, and heat-insulating at 90°C; after naturally aging the plate, applying lubricant on the surface and stamping it, and then artificially aging it after stamping; the heat-insulating time is ≥30 minutes; the natural aging is ≥15 days; the artificial aging condition is 180-190°C, and the heat is kept at 35-40 minutes; The lubricant is prepared by the following steps: Graphene oxide and deionized water were mixed and ultrasonically dispersed, 2,6-diaminopyridine was added, the temperature was set to 80-100°C, and the mixture was stirred for 30 minutes. The resulting mixture was dried to obtain modified graphene oxide; the modified graphene oxide was added to anhydrous ethanol, O,O-didodecyl dithiophosphate was added, the temperature was set to 60°C, and the mixture was stirred for 30 minutes. After the reaction was completed, the mixture was filtered and washed to obtain a solid filler; 20-30 parts of white oil, 10-12 parts of trihydroxypropane oleate, 4-5 parts of diisooctyl adipate, 2-2.5 parts of isobutylene sulfide, and 3-5 parts of a solid filler are weighed and stirred to obtain a lubricant; the amount ratio of graphene oxide, deionized water, and 2,6-diaminopyridine is 0.25 g:100 mL:0.1 g; the amount ratio of modified graphene oxide, O,O-didodecyl dithiophosphate, and anhydrous ethanol is 0.5 g:0.1 g:100 mL.

2. The process for preparing aluminum alloy for new energy vehicle body according to claim 1, characterized in that: Degassing, refining and slag removal are carried out under an inert gas atmosphere or nitrogen.

3. The process for preparing aluminum alloy for new energy vehicle body according to claim 1, characterized in that: The melting temperature is 740-760℃.

4. The process for preparing aluminum alloy for new energy vehicle body according to claim 1, characterized in that: The homogenization process in step S1 is as follows: heating at a rate of 10°C / min to 550-560°C, keeping the temperature for 18-20 hours, and quenching in cold water.

5. The process for preparing aluminum alloy for new energy vehicle body according to claim 1, characterized in that: In step S2, the hot rolling temperature is 420-430° C., and the cold rolling deformation is 0.6-0.7 mm / pass.