A high-yield heat treatment-free aluminum alloy material for thin-wall welding process of new energy vehicles and a preparation method thereof

Abstract

The application discloses a high-yield heat-treatment-free aluminum alloy material for a thin-wall welding process of a new energy vehicle, which is prepared from the following elements: Si: 4.5-6.5%; Mg: 0.3-0.5%; Fe: 0.08% or less; Ti: 0.15%; Sr: 0.015% or less; Zn: 0.5%; Re: 1-2%; Cu: 0.5% or less; Mn: 0.5-1.5%; Zr: 0.5%; and the rest is aluminum. The application further discloses a preparation method of the high-yield heat-treatment-free aluminum alloy material for the thin-wall welding process of the new energy vehicle. The high-yield heat-treatment-free aluminum alloy material for the thin-wall welding process of the new energy vehicle has a yield strength of more than 220 MPa and an elongation of more than 8% under a cast condition.

Description

Technical Field

[0001] This invention relates to aluminum alloy materials, and in particular to a method for preparing high-yield, heat-free aluminum alloy materials for thin-wall welding processes in new energy vehicles. Background Technology

[0002] For new energy vehicles, battery packs and auxiliary support products (such as front panel inserts) and thermal management system flow channel plates have the following characteristics: 1. Thin-walled components; 2. High sealing requirements, with annual leakage of flow channel plates required to be <0.1 mg / year; 3. High density requirements, with no porosity allowed in welds and an internal porosity requirement of <0.1%; 4. Yield strength >220 MPa. Based on these requirements, aluminum alloys using current processes generally employ A356.2 material. However, A356.2 material requires T6 heat treatment to meet these requirements, resulting in significant product deformation and negatively impacting cost and quality control for mass production. Currently, commonly used heat-treated aluminum alloys have a yield strength of around 140 MPa, which is insufficient to meet the 220 MPa requirement. Furthermore, they cannot be used in liquid forging processes due to the risk of segregation, leading to performance degradation.

[0003] Chinese invention patent application publication number CN109266922A discloses a formula for aluminum alloy castings for automotive parts, which is composed of the following raw materials in weight percentages: zinc, copper, magnesium, iron, titanium, silicon, manganese, molybdenum, platinum, cadmium, rhenium, hafnium, bismuth, silver, strontium, lead, boron, zirconium, and the remainder being aluminum. This patent application does not provide any experimental data, making it impossible to determine whether it possesses the advantages claimed.

[0004] Chinese invention patent application publication number CN108866391A discloses an aluminum alloy material for motorcycle wheel hubs, which is composed of the following elements: silicon, chromium, magnesium, titanium, strontium, iron, manganese, copper, zinc, calcium, nickel, rare earth elements, with the remainder being aluminum and unavoidable impurities; however, this patent application requires homogenization heat treatment after casting.

[0005] Chinese invention patent application publication number CN108624788A discloses a high-strength and high-toughness cast aluminum alloy and its preparation method, comprising the following components: silicon, copper, magnesium, manganese, titanium, boron, rhenium, modifier, impurity elements, and the balance being aluminum. In this patent, the die-casting part requires aging heat treatment for strengthening to obtain the cast aluminum alloy, and its yield strength does not exceed 220 MPa.

[0006] Chinese invention patent application publication number CN111197132A discloses a non-heat-treatable high-strength die-cast aluminum alloy material and its preparation method, relating to the field of metallic materials. The chemical composition of this non-heat-treatable high-strength die-cast aluminum alloy, by mass percentage, includes: Si, Zn, Fe, Cu, Mg, Ni, Ti, Sr, impurity elements, and the remainder being Al. This patent application features a high iron content and does not contain any rare earth elements.

[0007] Chinese invention patent application publication number CN112725662A discloses a high-strength, heat-resistant cast aluminum alloy material, which is composed of the following components in mass percentage: copper, manganese, magnesium, hafnium, aluminum oxynitride, with the balance being aluminum; the billet of the patent application is annealed at a temperature range of 200-250°C for 5-10 hours.

[0008] Chinese invention patent application publication number CN105986152A discloses an aluminum alloy for casting into parts, comprising at least one of the following: aluminum, silicon, magnesium (Mg), manganese (Mn), cerium (Ce), iron (Fe), copper (Cu), zinc (Zn), titanium (Ti), strontium (Sr), calcium (Ca), zirconium (Zr), bismuth (Bi), antimony (Sb), boron (B), molybdenum (Mo), scandium (Sc), and rhenium (Re). This patent application does not provide yield strength data.

[0009] Chinese invention patent application publication number CN105525159A discloses an A357 aluminum alloy material containing modifiers Sr and Ti, comprising: Si, Mg, Cu, Ti, Sr, Fe, with the remainder being Al. This patent application does not include rare earth elements or Mn.

[0010] Chinese Invention Patent Application Publication No. CN108193096A discloses a high-strength and high-toughness hypoeutectic aluminum-silicon casting alloy and its preparation method. The alloy consists of Si, Mg, Cu, Be, Sc, Zr, Sr, and Fe, with the balance being Al. This patent application requires failure treatment.

[0011] Chinese invention patent application publication number CN103103387A discloses an Al-Fe-C-RE aluminum alloy comprising Fe, Cu, Mg, Co, Be, Ca, Zn, Sr, Zr, Li, Na, K, V, Cr, Mn, Ni, Ga, Ge, Rb, Nb, Mo, Tc, Ru, Rh, Pd, Ag, Cd, In, Sn, Sb, Cs, Ba, Hf, Ta, W, Re, Os, Ir, Pt, Au, Tl, Pb, Bi, C, RE, Si, B, and Fe; with the balance being aluminum. This patent application requires intermittent annealing and aging treatment.

[0012] Chinese invention patent application publication number CN103103384A discloses an Al-Fe-Os-RE aluminum alloy, comprising: Fe, Cu, Mg, Co, Be, Ca, Zn, Sr, Zr, Li, Na, K, Ti, V, Cr, Mn, Ni, Ga, Ge, Rb, Nb, Mo, Tc, Ru, Rh, Pd, Ag, Cd, In, Sn, Sb, Cs, Ba, Hf, Ta, W, Re, Os, RE, Si, B; and the balance being aluminum. This patent application requires intermittent annealing and aging treatment.

[0013] Chinese invention patent application publication number CN103045913A discloses an Al-Fe-Ir-RE aluminum alloy, comprising: Fe, Cu, Mg, Co, Be, Ca, Zn, Sr, Zr, Li, Na, K, Ti, V, Cr, Mn, Ni, Ga, Ge, Rb, Nb, Mo, Tc, Ru, Rh, Pd, Ag, Cd, In, Sn, Sb, Cs, Ba, Hf, Ta, W, Re, Os, Ir, RE, Si, and B; with the balance being aluminum. This patent application requires intermittent annealing and aging treatment.

[0014] Chinese invention patent application publication number CN102978475A discloses an Al-Fe-Pt-RE aluminum alloy comprising: Fe, Cu, Mg, Co, Be, Ca, Zn, Sr, Zr, Li, Na, K, Ti, V, Cr, Mn, Ni, Ga, Ge, Rb, Nb, Mo, Tc, Ru, Rh, Pd, Ag, Cd, In, Sn, Sb, Cs, Ba, Hf, Ta, W, Re, Os, Ir, Pt, RE, Si, and B; with the balance being aluminum. This patent application requires intermittent annealing and aging treatment.

[0015] Chinese invention patent application publication number CN102978472A discloses an Al-Fe-Bi-RE aluminum alloy comprising: Fe, Cu, Mg, Co, Be, Ca, Zn, Sr, Zr, Li, Na, K, Ti, V, Cr, Mn, Ni, Ga, Ge, Rb, Nb, Mo, Tc, Ru, Rh, Pd, Ag, Cd, In, Sn, Sb, Cs, Ba, Hf, Ta, W, Re, Os, Ir, Pt, Au, Tl, Pb, Bi, RE, Si, and B; with the balance being aluminum. This patent application requires intermittent annealing and aging treatment.

[0016] Chinese invention patent application publication number CN102978473A discloses an Al-Fe-Pb-RE aluminum alloy comprising: Fe, Cu, Mg, Co, Be, Ca, Zn, Sr, Zr, Li, Na, K, Ti, V, Cr, Mn, Ni, Ga, Ge, Rb, Nb, Mo, Tc, Ru, Rh, Pd, Ag, Cd, In, Sn, Sb, Cs, Ba, Hf, Ta, W, Re, Os, Ir, Pt, Au, Tl, Pb, RE, Si, and B; with the balance being aluminum. This patent application requires intermittent annealing and aging treatment.

[0017] Chinese invention patent application publication number CN103103395A discloses an Al-Fe-Au-RE aluminum alloy comprising: Fe, Cu, Mg, Co, Be, Ca, Zn, Sr, Zr, Li, Na, K, Ti, V, Cr, Mn, Ni, Ga, Ge, Rb, Nb, Mo, Tc, Ru, Rh, Pd, Ag, Cd, In, Sn, Sb, Cs, Ba, Hf, Ta, W, Re, Os, Ir, Pt, Au, RE, Si, and B; with the balance being aluminum. This patent application requires intermittent annealing and aging treatment.

[0018] Chinese invention patent application publication number CN102978463A discloses an Al-Fe-Tl-RE aluminum alloy comprising: Fe, Cu, Mg, Co, Be, Ca, Zn, Sr, Zr, Li, Na, K, Ti, V, Cr, Mn, Ni, Ga, Ge, Rb, Nb, Mo, Tc, Ru, Rh, Pd, Ag, Cd, In, Sn, Sb, Cs, Ba, Hf, Ta, W, Re, Os, Ir, Pt, Au, Tl, RE, Si, and B; with the balance being aluminum. This patent application requires intermittent annealing and aging treatment.

[0019] Chinese invention patent application publication number CN102978476A discloses an Al-Fe-Re-RE aluminum alloy comprising: Fe, Cu, Mg, Co, Be, Ca, Zn, Sr, Zr, Li, Na, K, Ti, V, Cr, Mn, Ni, Ga, Ge, Rb, Nb, Mo, Tc, Ru, Rh, Pd, Ag, Cd, In, Sn, Sb, Cs, Ba, Hf, Ta, W, Re, RE, Si, and B; with the balance being aluminum. This patent application requires intermittent annealing and aging treatment.

[0020] Chinese invention patent application publication number CN102634710A discloses an aluminum-zinc-magnesium alloy, comprising: 1-3 wt% zinc, 3-9 wt% aluminum, 0.5-0.9 wt% titanium, 0.07-0.14 wt% zirconium, 0.02-0.11 wt% rhenium, with the remainder being magnesium and unavoidable impurities. The alloy may also include yttrium, manganese, strontium, and niobium. The aluminum-zinc-magnesium alloy of this invention utilizes the addition of zinc, aluminum, titanium, zirconium, and rhenium to a magnesium matrix to improve the strength of the magnesium alloy, and by selecting the appropriate proportions of each component, a good strength effect is achieved. Furthermore, in the preparation method, a three-step aging treatment is used to precipitation harden the aluminum-zinc-magnesium alloy, resulting in an aluminum-zinc-magnesium alloy with excellent hardness. This patent application requires aging treatment. Summary of the Invention

[0021] One of the technical problems that this invention aims to solve is to provide a high-yield, heat-free aluminum alloy material for thin-wall welding processes in new energy vehicles, addressing the issue that existing aluminum alloy materials require heat treatment to meet the requirement of yield strength > 220MPa, while the yield strength without heat treatment is only around 140MPa.

[0022] The second technical problem to be solved by the present invention is to provide a method for preparing the above-mentioned high-yield, heat-free aluminum alloy material for thin-wall welding process of new energy vehicles.

[0023] To achieve the above-mentioned objectives, the present invention provides a high-yield, heat-free aluminum alloy material for thin-wall welding processes in new energy vehicles, which is prepared from the following elements: Si: 4.5-6.5 wt%; Mg: 0.3-0.5 wt%; Fe: less than 0.08 wt%; Ti: 0.15 wt%; Sr: ≤0.015 wt%; Zn: 0.5 wt%; Re: 1-2 wt%; Cu: <0.5 wt%; Mn: 0.5-1.5 wt%; Zr: 0.5 wt%; the remainder being aluminum, and the wall thickness of the thin wall is 2.5-4 mm.

[0024] In this invention, the Si content is strictly controlled at 4.5-6.5 wt% to ensure basic strength and fluidity; Mg, as a key controlled element, has its content controlled at a base value of 0.3-0.5 wt% to facilitate the stability of the T6 strengthening process of aluminum alloy; Fe, as an impurity element, has its upper limit strictly controlled, with its content required to be controlled below 0.08 wt%; in addition, to improve and stabilize the elongation, the trace elements required are as follows: a) Ti content controlled at 0.15 wt%; b) Sr content not exceeding 0.015 wt%; c) Zn content controlled at 0.5 wt%; d) Re content controlled at 1-2 wt%; e) Cu content required to be less than 0.5 wt% to ensure the corrosion resistance of the alloy and to guarantee performance without heat treatment; Mn controlled at 0.5-1.5 wt%; Zr element 0.5 wt%.

[0025] The present invention provides a method for preparing high-yield, heat-free aluminum alloy materials for thin-wall welding processes in new energy vehicles, comprising the following steps:

[0026] a. Add aluminum, Si, Mg, Ti, Sr, Re, and Cu in proportion for centralized smelting, and control the centralized smelting temperature below 750℃; prevent excessive gas absorption of aluminum liquid and burn-off of Mg element; Mg in aluminum liquid is the core strength-enhancing element, and its burn-off must be considered. Check every 4 hours and replenish Mg in time to the required tolerance range.

[0027] b. Add Mn, Zn, and Zr in proportion for refining. The refining temperature should not be lower than 730℃. At the same time, blow N2 at the chute during the melting process to isolate the air and prevent oxidation inclusions caused by oxidation burn-off. Meanwhile, the tools must be coated with graphite coating during the refining process to prevent the aluminum liquid from increasing Fe and affecting the product performance.

[0028] c. Hydraulic forging: The casting temperature is controlled below 710℃, the injection speed is <0.4m / s, and the product is ensured to be free of porosity defects. Stirring is performed every 30 minutes.

[0029] d. T6 treatment: solution temperature is 545℃, time is not less than 4h, water quenching temperature does not exceed 80℃, aging temperature is 180℃, time is not less than 4h.

[0030] Due to the adoption of the above technical solution, the high yield strength and heat-free aluminum alloy material of the present invention for thin-wall welding process of new energy vehicles has a yield strength >220MPa and an elongation >8% under as-cast conditions. Detailed Implementation

[0031] The present invention will be described in detail below with reference to specific embodiments.

[0032] Example 1: Front panel component of battery pack:

[0033] The wall thickness of the front panel of the battery pack is 3-4mm.

[0034] It is prepared from the following elements: Si: 6.5 wt%; Mg: 0.48 wt%; Fe: 0.08 wt%; Ti: 0.15 wt%; Sr: 0.015 wt%; Zn: 0.5 wt%; Re: 1.5 wt%; Cu: 0.4 wt%; Mn: 0.8 wt%; Zr: 0.5%; the balance is aluminum. Detection method: Spectrometer is used for detection, and each batch meets the above composition requirements once.

[0035] Production process: Ingredient batching - smelting - refining and modification treatment - liquid forging - sawing and grinding - T6 - shot blasting - machining - leak testing - inspection and packaging;

[0036] Aluminum refining process: The refining temperature is not lower than 730℃. At the same time, N2 is blown at the chute during the melting process to isolate the air and prevent oxidation inclusions caused by oxidation and burning. Meanwhile, the tools must be coated with graphite coating during the refining process to prevent the aluminum liquid from increasing Fe and affecting product performance. The degassing time is 15 minutes and the settling time is 30 minutes.

[0037] Liquid forging: A 400T die casting machine is used at a speed of 0.6m / s, a pressure of 120Mpa, and an aluminum liquid temperature of 700℃. The coating concentration is 1:40 to ensure the mold's heat preservation and demolding. The part is removed from the mold after 140s.

[0038] T6: Solution treatment at 535℃, heat preservation time of 3h, aging temperature of 170℃, heat preservation time of 4h before sampling; meets the requirements of yield strength ≥220Mpa, elongation ≥8%, and airtightness meets the requirement of watertightness under 2kg air pressure.

[0039] Example 2: Rear panel of battery pack

[0040] The wall thickness of the rear panel of the battery pack is 3-4mm.

[0041] It is prepared from the following elements: Si: 5.5 wt%; Mg: 0.5 wt%; Fe: 0.08 wt%; Ti: 0.12 wt%; Sr: 0.015 wt%; Zn: 0.5 wt%; Re: 1 wt%; Cu: 0.5 wt%; Mn: 1.5 wt%; Zr: 0.5 wt%; the remainder is aluminum. Detection method: Spectrometer is used for detection, and each batch meets the above composition requirements once.

[0042] Production process: Ingredient batching - smelting - refining and modification treatment - liquid forging - sawing and grinding - T6 - shot blasting - machining - leak testing - inspection and packaging;

[0043] Aluminum refining process: The refining temperature is not lower than 730℃. At the same time, N2 is blown at the chute during the melting process to isolate the air and prevent oxidation inclusions caused by oxidation and burning. Meanwhile, the tools must be coated with graphite coating during the refining process to prevent the aluminum liquid from increasing Fe and affecting product performance. The degassing time is 15 minutes and the settling time is 30 minutes.

[0044] Liquid forging: A 400T die casting machine is used at a speed of 0.6m / s, a pressure of 120Mpa, and an aluminum liquid temperature of 700℃. The coating concentration is 1:40 to ensure the mold's heat preservation and demolding. The part is removed from the mold after 140s.

[0045] T6: Solution treatment at 535℃, heat preservation time of 3h, aging temperature of 170℃, heat preservation time of 4h before sampling; meets the requirements of yield strength ≥220Mpa, elongation ≥8%, and airtightness meets the requirement of watertightness under 2kg air pressure.

[0046] Example 3: Dashboard Skeleton

[0047] The wall thickness of the dashboard frame is 2.5-3mm.

[0048] It is prepared from the following elements: Si: 6.5 wt%; Mg: 0.48 wt%; Fe: 0.08 wt%; Ti: 0.15 wt%; Sr: 0.01 wt%; Zn: 0.4 wt%; Re: 1.2 wt%; Cu: 0.4 wt%; Mn: 1.2 wt%; Zr: 0.5 wt%; the remainder is aluminum. Detection method: Spectrometer analysis is used, and each batch meets the above composition requirements once.

[0049] Production process: Ingredient batching - smelting - refining and modification treatment - liquid forging - sawing and grinding - T6 - shot blasting - machining - inspection and packaging;

[0050] Aluminum refining process: The refining temperature is not lower than 730℃. At the same time, N2 is blown at the chute during the melting process to isolate the air and prevent oxidation inclusions caused by oxidation and burning. Meanwhile, the tools must be coated with graphite coating during the refining process to prevent the aluminum liquid from increasing Fe and affecting product performance. The degassing time is 15 minutes and the settling time is 30 minutes.

[0051] Liquid forging: A 1250T die casting machine is used at a speed of 0.8m / s, a pressure of 100Mpa, and an aluminum liquid temperature of 710℃. The coating concentration is 1:40 to ensure the mold's heat preservation and demolding. The part is removed from the mold after 210s.

[0052] T6: Solution treatment at 535℃, holding time for 3 hours, aging temperature at 170℃, holding time for 4 hours, then sampling is performed; the yield strength must be ≥220MPa and the elongation ≥8%.

[0053] Comparative Example 1: Vehicle Body Anti-collision Beam

[0054] The material, AlSi 10MnMg, is prepared from the following elements: Si: 10wt%; Mg: 0.4wt%; Fe: 0.08wt%; Ti: 0.2wt%; Sr: 0.02wt%; Mn: 0.6wt%; the remainder being aluminum. Testing method: Spectrometer analysis was used, and each batch was tested once to ensure the above composition was met.

[0055] Production process: Ingredient batching - smelting - refining and modification treatment - die casting - sawing and grinding - T6 - shot blasting - machining - inspection and packaging;

[0056] Aluminum refining process: The refining temperature is not lower than 730℃. At the same time, N2 is blown at the chute during the melting process to isolate the air and prevent oxidation inclusions caused by oxidation and burning. Meanwhile, the tools must be coated with graphite coating during the refining process to prevent the aluminum liquid from increasing Fe and affecting product performance. The degassing time is 15 minutes and the settling time is 30 minutes.

[0057] Die casting: 800T bedroom equipment is used for die casting at a speed of 3m / s, a pressure of 60Mpa, and an aluminum liquid temperature of 710℃. The coating concentration is 1:60 to ensure mold demolding. The part is removed from the mold after 70 seconds.

[0058] T6: Solution treatment at 535℃, holding time for 3 hours, aging temperature at 170℃, holding time for 4 hours, then sampling is performed; the yield strength must be ≥180MPa but <200MPa, and the elongation must be ≥6% but ≤8%.

[0059] Comparative Example 2: Battery Pack Support Frame

[0060] It is prepared from the following elements: Si: 6.5 wt%; Mg: 0.48 wt%; Fe: 0.08 wt%; Ti: 0.15 wt%; Sr: 0.01 wt%; Zn: 0.4 wt%; Re: 1.2 wt%; Cu: 0.4 wt%; Mn: 1.2 wt%; Zr: 0.5 wt%; the remainder is aluminum. Detection method: Spectrometer analysis is used, and each batch meets the above composition requirements once.

[0061] Production process: Ingredient batching - smelting - refining and modification treatment - liquid forging - sawing and grinding - T5 - shot blasting - machining - inspection and packaging;

[0062] Aluminum refining process: The refining temperature is not lower than 730℃. At the same time, N2 is blown at the chute during the melting process to isolate the air and prevent oxidation inclusions caused by oxidation and burning. Meanwhile, the tools must be coated with graphite coating during the refining process to prevent the aluminum liquid from increasing Fe and affecting product performance. The degassing time is 15 minutes and the settling time is 30 minutes.

[0063] Liquid forging: A 600T die casting machine is used at a speed of 3m / s, a pressure of 60Mpa, and an aluminum liquid temperature of 710℃. The coating concentration is 1:40 to ensure the mold's heat preservation and demolding. The part is removed from the mold after 80 seconds.

[0064] T6: Solution treatment at 515℃, holding time for 3 hours, aging temperature at 150℃, holding time for 4 hours, then sampling is performed; the yield strength must be ≥140MPa but <160MPa, and the elongation must be ≥10%.

Claims

1. A high yield heat treatment free aluminum alloy material for thin-walled welding process of new energy vehicles, characterized in that, Prepared from the following elements: Si: 4.5-6.5wt%; Mg: 0.3-0.5wt%; Fe: 0.08wt% or less; Ti: 0.15wt%; Sr: ≤0.015wt%; Zn: 0.5wt%; Re: 1-2wt%; Cu: <0.5wt%; Mn: 0.5-1.5wt%; Zr: 0.5wt%; the rest is aluminum, the thin-walled wall thickness is 2.5-4mm; The preparation method of the high-yield heat treatment-free aluminum alloy material for the thin-walled welding process of new energy vehicles comprises the following steps: a. proportionally adding aluminum, Si, Mg, Ti, Sr, Re, Cu for centralized smelting, and the centralized smelting temperature is controlled below 750 DEG C; prevent the excessive air absorption of the aluminum liquid and the burning of the Mg element; the Mg in the aluminum liquid is a core strength element and must be considered for burning loss, and is detected every 4 hours and supplemented with Mg in time to be within the required tolerance range; b. proportionally adding Mn, Zn and Zr for refining, the refining temperature is not less than 730 DEG C, and N2 is blown at the intersection during the melting process to isolate air and prevent oxidation inclusions caused by oxidation burning loss; meanwhile, the tool must be coated with graphite paint during the refining process to prevent the increase of Fe in the aluminum liquid and affect the product performance; c. hydraulic die forging: the casting temperature is controlled below 710 DEG C, the injection speed is <0.4 m / s, air hole defects are ensured not to be generated in the product, and the aluminum liquid is stirred every 30 minutes; d. T6 treatment: the solid solution temperature is 545 DEG C, the time is not less than 4h, the water quenching temperature is not more than 80 DEG C, the aging temperature is 180 DEG C, and the time is not less than 4h.