Preparation method of aluminum alloy with high strength and high bending angle

Abstract

The invention provides a preparation method of a high-strength and high-bending-angle aluminum alloy, which comprises the following steps: S1, respectively weighing raw materials according to the mass percent of elements in the aluminum alloy, heating and melting the raw materials into melt, and then deslagging, refining and removing impurities to obtain aluminum alloy melt; s2, casting the molten aluminum alloy to obtain an aluminum alloy round casting rod; s3, the aluminum alloy round casting rod is homogenized, and a long aluminum alloy round casting rod is obtained; s4, cutting the aluminum alloy round casting rod to obtain an equal-length aluminum alloy short casting rod suitable for extrusion; s5, the aluminum alloy short casting rod is heated and then subjected to high-temperature extrusion, online quenching is conducted while extrusion discharging is conducted, and a quenched profile is obtained; and S6, the quenched profile is subjected to two-stage overaging heat treatment, and the high-strength and high-bending-angle aluminum alloy is obtained. The mechanical performance of the product is adjusted according to the characteristics that the aluminum alloy has the same alloy components and the same processing technology, the aging performance peak value is basically consistent, and the performance is reduced during overaging of the aluminum alloy, so that the requirement of the bending angle is met.

Description

Technical Field

[0001] The invention relates to the technical field of nonferrous metal processing, and in particular to a method for preparing a high-strength and high-bending-angle aluminum alloy. Background Art

[0002] Due to their working characteristics, automobile anti-collision beams and other components have higher mechanical property requirements for tensile strength, yield strength, and elongation of their main aluminum alloys. At the same time, they also have bending angle requirements to increase the cushioning effect when the anti-collision beam collides. Generally, 6 series T6 aluminum alloy will be selected, and the bending angle of aluminum alloy of the same grade is generally negatively correlated with the yield strength. Combined with the original tensile strength and yield strength requirements, it is difficult to control the performance of the product.

[0003] The tensile strength and yield strength of most 6 series aluminum alloys increase with the extension of aging time. After reaching the maximum value, the performance will slowly decrease if the aging time is further extended, which is called over-aging. The rate of decrease of alloy performance during over-aging is much lower than the rate of increase of performance during normal aging. By using this characteristic, the purpose of adjusting the mechanical properties of products in batches within a certain range can be achieved by adding an over-aging heat treatment after normal aging. Summary of the invention

[0004] The purpose of the present invention is to overcome the deficiencies in the prior art and to provide a method for preparing 6 series T6 state aluminum alloy profiles with overaging effect such as 6061, 6082, etc., which can meet the requirements of high tensile strength and yield strength while meeting the bending angle requirements.

[0005] The technical solution adopted by the present invention is:

[0006] A method for preparing a high-strength and high-bending-angle aluminum alloy, comprising the following steps:

[0007] Step S1. weighing raw materials and grain refiners according to the mass percentage of elements in each aluminum alloy of GB T 31906 series, then adding the raw materials and grain refiners into a smelting furnace, heating and melting them into a molten liquid, and then deslagging, refining and removing impurities from the molten liquid to obtain an aluminum alloy molten liquid;

[0008] Step S2. Casting the aluminum alloy melt obtained in step S1 to obtain an aluminum alloy round cast rod;

[0009] Step S3. homogenizing the aluminum alloy round cast rod obtained in step S2 to obtain a long aluminum alloy round cast rod;

[0010] Step S4. Cutting the aluminum alloy round cast rod obtained in step S3 to obtain short aluminum alloy cast rods of equal length suitable for extrusion;

[0011] Step S5. The aluminum alloy short cast rod obtained in step S4 is heated and then extruded at high temperature, and the extruded material is quenched online at the same time to obtain a quenched profile;

[0012] Step S6. Perform a double-stage over-aging heat treatment on the quenched profile obtained in step S5 to obtain an aluminum alloy with high strength and high bending angle.

[0013] Preferably, the method for preparing the high-strength and high-bending-angle aluminum alloy, wherein: the temperature of the molten metal in step S1 is 730-760°C, the refining temperature is 750-790°C, the refining is carried out in a high-purity argon atmosphere, and the refining time is 20-40 minutes.

[0014] Preferably, the method for preparing the high-strength and high-bending-angle aluminum alloy, wherein: the impurity removal in step S1 is specifically: the refined molten metal is kept warm and allowed to stand for 20 to 30 minutes, then argon gas is introduced to remove hydrogen, and finally the aluminum liquid is filtered to obtain an aluminum alloy melt.

[0015] Preferably, in the method for preparing the high-strength and high-bending-angle aluminum alloy, the casting temperature in step S2 is 690-720°C.

[0016] Preferably, in the method for preparing the high-strength and high-bending-angle aluminum alloy, the homogenization temperature in step S3 is 560° C.-580° C., and the holding time is 7.75-8.25 h.

[0017] Preferably, in the method for preparing the high-strength and high-bending-angle aluminum alloy, step S5 specifically comprises the following steps:

[0018] Step S51. Preheating the aluminum alloy short cast rod, the mold barrel and the mold, then installing the mold barrel into the mold to obtain an extrusion mold, and then placing the aluminum alloy short cast rod into the extrusion mold for high-temperature extrusion;

[0019] Step S52: Quench, straighten and cut the high-temperature extruded aluminum alloy short cast rods online to a desired length to obtain aluminum alloy quenched extruded profiles.

[0020] Preferably, the method for preparing the high-strength and high-bending-angle aluminum alloy, wherein: in step S51, the aluminum alloy short cast rod is gradient preheated from head to tail, the head preheating temperature is 505°C-540°C, and the gradient is 3-6°C / 100mm; the die barrel preheating temperature is 425°C-445°C; the mold preheating temperature is 460°C-500°C; and the discharge speed of high-temperature extrusion is 3.5m / min-8m / min.

[0021] Preferably, in the method for preparing the high-strength and high-bending-angle aluminum alloy, the double-stage over-aging heat treatment in step S6 is specifically as follows: the first-stage aging heat treatment temperature is 170-180°C, the holding time is 6-7h, and the second-stage aging heat treatment temperature is 190-210°C, the holding time is 1-3h.

[0022] Advantages of the present invention:

[0023] The preparation method of the high-strength and high-bending-angle aluminum alloy of the present invention utilizes the characteristics that the aging performance peak values ​​of aluminum alloys with the same alloy composition and the same processing technology are basically the same, and the performance of aluminum alloys decreases when over-aged to adjust the mechanical properties of the product to meet the requirements of the bending angle; because the rate of performance reduction of aluminum alloys over-aging is slow, mass production of products can be achieved, and the mechanical properties of products can be adjusted within a certain range. DETAILED DESCRIPTION

[0024] The present invention will be further described below in conjunction with specific embodiments.

[0025] Example 1

[0026] A method for preparing a high-strength and high-bending-angle aluminum alloy comprises the following steps:

[0027] Step S1. According to the requirements of GB T 3190 6082, the proportions of the elements are made (Fe: 0.202; Si: 0.87; Cu: 0.0726; Mg: 0.735; Mn: 0.445; Zn: 0.0049; Cr: 0.0321; Ti: 0.0685, the rest is Al, and the sum of the above is 100%), pure aluminum ingot, pure magnesium ingot, aluminum silicon master alloy, manganese agent, aluminum copper alloy, zinc ingot, chromium agent, pure iron powder and aluminum titanium boron grain refiner are weighed respectively, the manganese agent and chromium agent are pure manganese and pure chromium, and then they are added into a smelting furnace in sequence, heated and melted into a melt, and then sodium fluoroaluminate slag remover is added to the melt to remove the slag, and alloy is added, the composition is adjusted, stirred, and the chemical composition is sampled and analyzed by spectroscopy until it reaches GB T 3190. The proportion of each element required by the 6082 grade is then refined and impurities are removed to obtain an aluminum alloy melt; the temperature of the melt is 750°C, the refining temperature is 765°C, and the refining is carried out in a high-purity argon atmosphere for 30 minutes to remove hydrogen and impurities in the solution; the impurity removal is specifically as follows: the refined melt is kept warm and allowed to stand for 25 minutes, then argon is introduced to remove hydrogen, and finally the aluminum melt is filtered to obtain an aluminum alloy melt;

[0028] Step S2. The aluminum alloy melt obtained in step S1 is low-pressure vacuum cast at 700°C to obtain a D152 aluminum alloy round cast rod;

[0029] Step S3. homogenizing the aluminum alloy round cast rod obtained in step S2 at a homogenization temperature of 570° C. for 8 hours to obtain a D152 long aluminum alloy round cast rod;

[0030] Step S4. Cutting the aluminum alloy round cast rod obtained in step S3 to obtain short aluminum alloy cast rods of equal length D152*880 suitable for extrusion;

[0031] Step S5. The aluminum alloy short cast rod obtained in step S4 is heated and then extruded at high temperature, and the extruded material is quenched online at the same time to obtain a quenched profile;

[0032] Step S5 specifically includes the following steps:

[0033] Step S51. Preheating the aluminum alloy short cast rod, the mold barrel and the mold, then installing the mold barrel into the mold to obtain an extrusion mold, and then placing the aluminum alloy short cast rod into the extrusion mold for high-temperature extrusion; the preheating temperature of the aluminum alloy short cast rod head is 520°C, and gradient preheating is adopted, and the gradient is 4°C / 100mm; the preheating temperature of the mold barrel is 435°C; the preheating temperature of the mold is 480°C; the discharge speed of high-temperature extrusion is 4.15m / min;

[0034] Step S52. Quench, straighten, and cut the high-temperature extruded aluminum alloy short cast rods online through a water tank to a desired length to obtain aluminum alloy quenched extruded profiles;

[0035] Step S6. Perform a double-stage over-aging heat treatment on the quenched profile obtained in step S5. Specifically, the double-stage over-aging heat treatment is as follows: the first-stage aging heat treatment temperature is 175°C, the holding time is 7 hours, and the second-stage aging heat treatment temperature is 202°C, the holding time is 1.5 hours, to obtain a high-strength and high-bending-angle aluminum alloy.

[0036] Example 2

[0037] A method for preparing a high-strength and high-bending-angle aluminum alloy comprises the following steps:

[0038] Step S1. According to the requirements of GB T 3190 6082, the proportions of the elements are made (Fe: 0.202; Si: 0.87; Cu: 0.0726; Mg: 0.735; Mn: 0.445; Zn: 0.0049, Cr: 0.0321, Ti: 0.0685, the rest is Al, and the total is 100%), pure aluminum ingots, pure magnesium ingots, aluminum silicon master alloys, manganese agents, aluminum copper alloys, zinc ingots, chromium agents, pure iron powders and aluminum titanium boron grain refiners are weighed respectively, and then added into a smelting furnace in sequence, heated and melted into a melt, and then sodium fluoroaluminate slag remover is added to the melt to remove the slag, and alloys are added, the composition is adjusted, stirred, and the chemical composition is sampled and analyzed by spectroscopy until it reaches GB The proportion of each element required by the T31906082 grade is followed by refining and impurity removal to obtain an aluminum alloy melt; the temperature of the melt is 750°C, the refining temperature is 765°C, and the refining is carried out in a high-purity argon atmosphere for 30 minutes to remove hydrogen and impurities in the solution; the impurity removal is specifically as follows: the refined melt is kept warm and allowed to stand for 25 minutes, then argon is introduced to remove hydrogen, and finally the aluminum melt is filtered to obtain an aluminum alloy melt;

[0039] Step S2. The aluminum alloy melt obtained in step S1 is subjected to low-pressure vacuum casting at 700° C. to obtain a D152 aluminum alloy round cast rod;

[0040] Step S3. homogenizing the aluminum alloy round cast rod obtained in step S2 at a homogenization temperature of 570° C. for 8 hours to obtain a D152 long aluminum alloy round cast rod;

[0041] Step S4. Cutting the aluminum alloy round cast rod obtained in step S3 to obtain short aluminum alloy cast rods of equal length D152*880 suitable for extrusion;

[0042] Step S5. The aluminum alloy short cast rod obtained in step S4 is heated and then extruded at high temperature, and the extruded material is quenched online at the same time to obtain a quenched profile;

[0043] Step S5 specifically includes the following steps:

[0044] Step S51. Preheating the aluminum alloy short cast rod, the mold barrel and the mold, then installing the mold barrel into the mold to obtain an extrusion mold, and then placing the aluminum alloy short cast rod into the extrusion mold for high-temperature extrusion; the preheating temperature of the aluminum alloy short cast rod head is 525°C, and gradient preheating is adopted, and the gradient is 5°C / 100mm; the preheating temperature of the mold barrel is 435°C; the preheating temperature of the mold is 480°C; the discharge speed of high-temperature extrusion is 6.8m / min;

[0045] Step S52. Quench, straighten, and cut the high-temperature extruded aluminum alloy short cast rods online through a water tank to a desired length to obtain aluminum alloy quenched extruded profiles;

[0046] Step S6. Perform a double-stage over-aging heat treatment on the quenched profile obtained in step S5. Specifically, the double-stage over-aging heat treatment is as follows: the first-stage aging heat treatment temperature is 175°C, the holding time is 7 hours, and the second-stage aging heat treatment temperature is 193°C, the holding time is 1.2 hours, to obtain a high-strength and high-bending-angle aluminum alloy.

[0047] The high-strength and high-bending-angle aluminum alloys of Examples 1-2 were tested for product mechanical properties and bending angles, and the results are shown in Table 1.

[0048] Table 1

[0049] Example Tensile strength / MPa Yield strength / MPa Elongation / % Bending Angle Example 1 313.69 296.81 11.2％ 95.31 Example 2 303.16 280.16 14.3％ 112.23

[0050] Finally, it should be noted that the above specific implementation methods are only used to illustrate the technical solution of the present invention rather than to limit it. Although the present invention has been described in detail with reference to examples, those skilled in the art should understand that the technical solution of the present invention can be modified or replaced by equivalents without departing from the spirit and scope of the technical solution of the present invention, which should be included in the scope of the claims of the present invention.

Claims

1. A method for preparing a high-strength and high-bending-angle aluminum alloy, characterized in that: The following steps are involved: Step S1. weighing raw materials and grain refiners according to the mass percentage of elements in each aluminum alloy of GB T 31906 series, then adding the raw materials and grain refiners into a smelting furnace, heating and melting them into a molten liquid, and then removing slag, refining and impurities from the molten liquid to obtain an aluminum alloy molten liquid; Step S2. Casting the aluminum alloy melt obtained in step S1 to obtain an aluminum alloy round cast rod; Step S3. homogenizing the aluminum alloy round cast rod obtained in step S2 to obtain a long aluminum alloy round cast rod; Step S4. Cutting the aluminum alloy round cast rod obtained in step S3 to obtain short aluminum alloy cast rods of equal length suitable for extrusion; Step S5. The aluminum alloy short cast rod obtained in step S4 is heated and then extruded at high temperature, and the extruded material is quenched online at the same time to obtain a quenched profile; Step S6. Perform a double-stage over-aging heat treatment on the quenched profile obtained in step S5 to obtain an aluminum alloy with high strength and high bending angle.

2. The method for preparing the high-strength and high-bending-angle aluminum alloy according to claim 1, characterized in that: In step S1, the temperature of the melt is 730-760°C, the refining temperature is 750-790°C, the refining is carried out in a high-purity argon atmosphere, and the refining time is 20-40 minutes.

3. The method for preparing the high-strength and high-bending-angle aluminum alloy according to claim 1, characterized in that: The impurity removal in step S1 is specifically as follows: the refined molten metal is kept warm and allowed to stand for 20 to 30 minutes, argon gas is then introduced to remove hydrogen, and finally the aluminum liquid is filtered to obtain an aluminum alloy melt.

4. The method for preparing the high-strength and high-bending-angle aluminum alloy according to claim 1, characterized in that: The casting temperature in step S2 is 690-720°C.

5. The method for preparing the high-strength and high-bending-angle aluminum alloy according to claim 1, characterized in that: In step S3, the homogenization temperature is 560° C.-580° C., and the insulation time is 7.75-8.25 h.

6. The method for preparing the high-strength and high-bending-angle aluminum alloy according to claim 1, characterized in that: Step S5 specifically includes the following steps: Step S51. Preheating the aluminum alloy short cast rod, the mold barrel and the mold, then installing the mold barrel into the mold to obtain an extrusion mold, and then placing the aluminum alloy short cast rod into the extrusion mold for high-temperature extrusion; Step S52: Quench, straighten and cut the high-temperature extruded aluminum alloy short cast rods online to a desired length to obtain aluminum alloy quenched extruded profiles.

7. The method for preparing the high-strength and high-bending-angle aluminum alloy according to claim 6, characterized in that: In step S51, the aluminum alloy short cast rod is gradient preheated from the head to the tail, the head preheating temperature is 505℃-540℃, the gradient is 3-6℃ / 100 mm; the die barrel preheating temperature is 425℃-445℃; the mold preheating temperature is 460℃-500℃; the discharge speed of high temperature extrusion is 3.5m / min-8m / min.

8. The method for preparing the high-strength and high-bending-angle aluminum alloy according to claim 1, characterized in that: The double-stage over-aging heat treatment in step S6 is specifically as follows: the first stage aging heat treatment temperature is 170-180° C., the holding time is 6-7 h, and the second stage aging heat treatment temperature is 190-210° C., the holding time is 1-3 h.