Extrusion process for an aluminium alloy profile

Abstract

This invention discloses an extrusion forming process for aluminum alloy profiles, comprising the following steps: S1, configuring raw aluminum ingots and intermediate alloys according to the weight percentage of the constituent elements of the aluminum alloy; S2: transferring the aluminum ingots and aluminum alloy raw materials into a melting furnace to melt into liquid aluminum alloy, refining, degassing and removing impurities, and casting the liquid aluminum alloy into aluminum alloy ingots; S3: homogenizing the aluminum alloy ingots obtained in S2 with heat treatment, the heat treatment process being: heating to 470-490℃ and holding for 3-5 hours, then heating to 565-580℃ and holding for 7-10 hours, and cooling to obtain homogenized aluminum alloy ingots; S4: heating the extrusion cylinder, aluminum alloy ingots and molds, the heating temperature of the aluminum alloy ingots being 520-535℃, and extruding the aluminum alloy ingots to obtain aluminum alloy extruded parts; S5: after quenching, straightening, sawing and aging, obtaining finished aluminum alloy workpieces. By adjusting the elemental composition of aluminum alloys, the mechanical properties and surface quality of the workpieces are improved, and the profile extrusion is completed with a smaller extrusion pressure and a higher extrusion temperature, thereby enhancing the solution treatment effect.

Description

Technical Field

[0001] This invention relates to the field of aluminum alloy technology, and more specifically to an extrusion molding process for aluminum alloy profiles. Background Technology

[0002] 6-series aluminum alloys are aluminum alloys with magnesium and silicon as the main alloying elements and Mg2Si phase as the strengthening phase. They belong to heat-treatable aluminum alloys. The alloys have advantages such as moderate strength, high corrosion resistance, no tendency for stress corrosion cracking, good weldability, unchanged corrosion performance in the weld zone, and good formability and processability. They are widely used in the manufacture of structural components such as robotic arms, conveyor belt supports, cleanroom gantry frames, and lighting housings.

[0003] The forming method of aluminum alloy workpieces includes steps such as extrusion cylinder, die, heating of aluminum rod, extrusion, quenching, tension leveling, sawing, aging, and surface treatment. Increasing the extrusion temperature of aluminum rods can improve the plasticity of aluminum rods and reduce extrusion pressure, as well as improve the solid solution effect of heat-treated strengthening phases in aluminum alloys and optimize mechanical properties; however, excessively high temperatures can cause overheating, affecting the mechanical properties and surface quality of the workpiece, thereby limiting the application range of aluminum alloys. Summary of the Invention

[0004] One of the objectives of this invention is to overcome the deficiencies in the prior art and provide an extrusion molding process for aluminum alloy profiles. By adjusting the elemental composition of the aluminum alloy, the mechanical properties and surface quality of the workpiece are improved, which facilitates the extrusion of the profiles with smaller extrusion pressure and higher extrusion temperature, and optimizes the solution treatment effect.

[0005] To achieve the above-mentioned technical effects, the technical solution of the present invention is as follows: an extrusion forming process for aluminum alloy profiles, comprising the following steps:

[0006] S1, raw aluminum ingots and master alloys are prepared according to the weight percentage of the constituent elements of the aluminum alloy: Mg: 0.55%~0.65%, Si: 0.4%~0.5%, Fe: 0.1%~0.2%, Zr: 0.01%~0.04%, Nb: 0.02%~0.05%, Ga: 0.01%~0.03%, Mn: <0.1%, C <0.1%, with the balance being aluminum and unavoidable impurities;

[0007] S2: Transfer aluminum ingots and aluminum alloy raw materials into a melting furnace to melt into liquid aluminum alloy. After refining, degassing and removing impurities, melt the liquid aluminum alloy into aluminum alloy ingots.

[0008] S3: The aluminum alloy ingot obtained by homogenization heat treatment S2 is heated to 470-490℃ and held for 3-5 hours, then heated to 565-580℃ and held for 7-10 hours, and then cooled to obtain homogenized aluminum alloy ingot.

[0009] S4: Heating the extrusion cylinder, aluminum alloy ingot and mold, the heating temperature of the aluminum alloy ingot is 520~535℃, extruding the aluminum alloy ingot to obtain aluminum alloy extrusions;

[0010] S5. After quenching, straightening, sawing, and aging, the finished aluminum alloy workpiece is obtained.

[0011] Furthermore, the S3 heat treatment process is as follows: heat to 475-485℃ and hold for 3-5 hours, then heat to 570-580℃ and hold for 7-10 hours, and then cool.

[0012] The preferred technical solution is that the master alloy of S1 includes aluminum-zirconium-carbon master alloy, aluminum-niobium master alloy and aluminum-gallium master alloy.

[0013] Zirconium is beneficial for improving the thermal properties of aluminum alloys, while niobium, gallium, and limited carbon content are all beneficial for improving the corrosion resistance of aluminum alloys. The above-mentioned contents of zirconium, niobium, and gallium have a good grain refining effect on the alloy of 6-series aluminum alloys.

[0014] The preferred technical solution is that the weight percentage of the constituent elements of the aluminum alloy is as follows: Mg: 0.55%~0.6%, Si: 0.40%~0.46%, Fe: 0.1%~0.16%, Zr: 0.01%~0.03%, Nb: 0.02%~0.05%, Ga: 0.01%~0.02%, Mn: <0.05%, C <0.05%, with the balance being aluminum and unavoidable impurities, and the sum of the weight percentages of Zr and Nb not exceeding 0.07%.

[0015] The preferred technical solution is that the extrusion speed in S4 is 16-19 m / min.

[0016] The preferred technical solution is that the process parameters for the quenching step are: quenching inlet temperature 500-510℃, quenching outlet temperature <70℃, and cooling rate 100-120℃ / min. Further, the cooling rate is 105-115℃ / min.

[0017] A preferred technical solution is that the workpiece temperature during the tension leveling process is below 50°C; the tension rate is calculated as the percentage of the difference in length between the extruded part before and after tensioning relative to the length of the extruded part before tensioning, and is 1.2% to 1.5%. Further, the tension rate is 1.3% to 1.4%.

[0018] The preferred technical solution is that the aging process parameters for aluminum alloy extrusions are: aging temperature 140~155℃, aging time 10~15h.

[0019] The preferred technical solution is that the mass percentage of carbon in the aluminum-zirconium-carbon master alloy is no more than 0.15%, and the mass percentage of zirconium is 5% to 10%; the aluminum-niobium master alloy is AlNb50; and the aluminum-gallium master alloy is AlGa10.

[0020] A preferred technical solution is that the heating temperature of the extrusion cylinder is 400–450°C, and the heating temperature of the die is 460–480°C. Further, the heating temperature of the extrusion cylinder is 420–450°C.

[0021] A preferred technical solution is that the cooling rate of the homogenization heat treatment in S3 is 8–11 °C / min. Further, the cooling rate is 9–11 °C / min.

[0022] The advantages and beneficial effects of this invention are as follows:

[0023] The extrusion process of this aluminum alloy profile optimizes the alloy composition based on the elemental composition of the original 6-series alloys, adding zirconium, niobium, gallium and limiting the carbon content to improve the corrosion resistance of the aluminum alloy and refine the alloy grains. The improved aluminum alloy feed meets the extrusion production requirements at higher extrusion temperatures, and the resulting aluminum alloy extrusions have no overheated structure or obvious overheated surface features such as blackening and bubbles.

[0024] A predetermined extrusion speed is achieved at a higher extrusion temperature, resulting in a reduction in the extrusion pressure used.

[0025] Higher extrusion temperatures also help to enhance the solution treatment effect and improve the mechanical properties of aluminum alloy extrusions. Detailed Implementation

[0026] The specific embodiments of the present invention will be further described below with reference to examples. These examples are only used to more clearly illustrate the technical solutions of the present invention and should not be construed as limiting the scope of protection of the present invention.

[0027] Production of aluminum-zirconium-carbon master alloy: Pure aluminum, zirconium shavings, and graphite powder are weighed according to the following weight percentages: 92% Al, 8.7% Zr, and 0.03% carbon. The graphite powder is pretreated by soaking in potassium fluorozirconate solution and then dried. The induction furnace temperature is set to 860±10℃. Pure aluminum is melted in the induction furnace, and then zirconium shavings and graphite powder are added to the molten aluminum in sequence and mixed. The mixture is kept at a constant temperature and stirred until homogenized. The aluminum-zirconium-carbon alloy wire is produced by continuous casting and rolling.

[0028] Example 1

[0029] Aluminum alloy raw materials, including aluminum ingots, silicon-aluminum alloy, pure magnesium, aluminum-zirconium-carbon alloy wire, AlNb50, and AlGa10, are prepared according to the following proportions: Mg: 0.55%–0.65%, Si: 0.4%–0.5%, Fe: 0.1%–0.2%, Zr: 0.01%–0.04%, Nb: 0.02%–0.05%, Ga: 0.01%–0.03%, Mn: <0.1%, and C <0.1%.

[0030] The furnace temperature is set to 780℃. The aluminum ingot and aluminum-silicon alloy are heated and melted. After holding at this temperature for a period of time, pure magnesium, aluminum-niobium master alloy and aluminum-gallium master alloy are added and melted. Then the furnace temperature is fixed at 760℃, and refining agent is added to remove gas and slag. After standing for 40 minutes, the aluminum ingot is cast.

[0031] Composition analysis: Mg: 0.59%, Si: 0.44%, Fe: 0.13%, Zr: 0.03%, Nb: 0.04%, Ga: 0.02%, Mn: 0.04%, C: 0.003%, Al: 98.69%.

[0032] The aluminum alloy ingot obtained by homogenization heat treatment S2 is heat treated as follows: heating to 480℃ and holding for 4 hours, then heating to 575℃ and holding for 7 hours, and cooling at a cooling rate of 8.5℃ / min to obtain a homogenized aluminum alloy ingot.

[0033] S4: Heated extrusion cylinder, aluminum alloy ingot and conveyor belt aluminum alloy support extrusion die. The heating temperature of the extrusion cylinder is 440~445℃, the heating temperature of the die is 460~465℃, the heating temperature of the aluminum alloy ingot is 525~530℃, the extrusion speed in S4 is 16.5m / min, and aluminum alloy extrusion is obtained by extruding the aluminum alloy ingot.

[0034] S5. Quenching: The process parameters for the quenching step are: quenching temperature 500℃, quenching temperature 60℃, and cooling rate 110℃ / min.

[0035] Stretch straightening: The initial temperature of the workpiece after stretch straightening is 45℃; the stretching rate is calculated as the percentage of the difference in length of the extruded part before and after stretching to the length of the extruded part before stretching, and the stretching rate is 1.35%; sawing.

[0036] Aging: The aging process parameters for aluminum alloy extrusions are: aging temperature 145±3℃, aging time 12h, resulting in an aluminum alloy bracket with a wall thickness of 4mm.

[0037] Example 1: The aluminum alloy bracket has a smooth surface, uniform color, and no overheated bubbles. After testing, the finished aluminum alloy bracket has a tensile strength of 252 MPa, a yield strength of 220 MPa, an elongation after fracture of 19.3%, and a hardness HV of 116.

[0038] Example 2

[0039] Example 2 uses the same aluminum alloy as Example 1, and the extrusion process steps are as follows:

[0040] S4: Heated extrusion cylinder, aluminum alloy ingot and conveyor belt aluminum alloy support extrusion die. The heating temperature of the extrusion cylinder is 440~445℃, the heating temperature of the die is 460~465℃, the heating temperature of the aluminum alloy ingot is 490~495℃, the extrusion speed in S4 is 12m / min, and aluminum alloy extrusion is obtained by extruding the aluminum alloy ingot.

[0041] S5. Quenching: The process parameters for the quenching step are: quenching temperature 500℃, quenching temperature 60℃, and cooling rate 105℃ / min.

[0042] Stretch straightening: The workpiece temperature for stretch straightening is 45℃; the stretching rate is calculated as the percentage of the difference in length of the extruded part before and after stretching relative to the length of the extruded part before stretching, and the stretching rate is 1.25%; sawing;

[0043] Aging: The aging process parameters for aluminum alloy extrusions are: aging temperature 145±3℃, aging time 12h, resulting in an aluminum alloy bracket with a wall thickness of 4mm.

[0044] The surface of the aluminum alloy bracket in Example 2 is similar to that in Example 1, with no overheating characteristics; the finished aluminum alloy bracket has a tensile strength of 233 MPa, a yield strength of 210 MPa, an elongation after fracture of 18.6%, and a hardness HV of 107.

[0045] Example 3

[0046] Example 3 uses the same aluminum alloy as Example 1, and the extrusion process steps are as follows:

[0047] S4: Heated extrusion cylinder, aluminum alloy ingot and conveyor belt aluminum alloy support extrusion die. The heating temperature of the extrusion cylinder is 440~445℃, the heating temperature of the die is 460~465℃, the heating temperature of the aluminum alloy ingot is 480~485℃, the extrusion speed in S4 is 9m / min, and aluminum alloy extrusion is obtained by extruding the aluminum alloy ingot.

[0048] S5. Quenching: The process parameters for the quenching step are: quenching temperature 500℃, quenching temperature 60℃, and cooling rate 105℃ / min.

[0049] Stretch straightening: The workpiece temperature for stretch straightening is 45℃; the stretching rate is calculated as the percentage of the difference in length of the extruded part before and after stretching relative to the length of the extruded part before stretching, and the stretching rate is 1.25%; sawing;

[0050] Aging: The aging process parameters for aluminum alloy extrusions are: aging temperature 145±3℃, aging time 12h, resulting in an aluminum alloy bracket with a wall thickness of 4mm.

[0051] Example 3: The aluminum alloy bracket showed no signs of overheating; the finished aluminum alloy bracket had a tensile strength of 228 MPa, a yield strength of 203 MPa, an elongation after fracture of 18.4%, and a hardness HV of 99.

[0052] Example 4

[0053] Example 4 uses the same aluminum alloy and extrusion process parameters as Example 1, with the following differences in aging process parameters:

[0054] Aging: The aging process parameters for aluminum alloy extrusions are: aging temperature 160±3℃, aging time 12h, resulting in an aluminum alloy bracket with a wall thickness of 4mm.

[0055] Example 4: The aluminum alloy bracket showed no signs of overheating. Testing revealed that the finished aluminum alloy bracket had a tensile strength of 249 MPa, a yield strength of 203 MPa, an elongation at break of 17.6%, and a hardness (HV) of 95.

[0056] Example 5

[0057] The difference between Example 5 and Example 1 is as follows: S5, Quenching: The process parameters for the quenching step are: quenching temperature 500℃, quenching temperature 60℃, water mist cooling, and cooling rate 123℃ / min.

[0058] Example 5: The aluminum alloy bracket showed no signs of overheating. Testing revealed that the finished aluminum alloy bracket had a tensile strength of 244 MPa, a yield strength of 215 MPa, an elongation after fracture of 16.8%, and a hardness HV of 105.

[0059] Comparative Example

[0060] The comparative example used 6063 aluminum alloy with the following elemental composition as raw material: Mg: 0.57%, Si: 0.40%, Fe: 0.13%, Cu: 0.018%, Mn: 0.04%, Cr: 0.012%, Bi: 0.006%, Ga: 0.015%, Al: 98.77%, and unavoidable impurity elements such as V, Pb, Sn, and B (spectral analysis).

[0061] S4: Heated extrusion cylinder, aluminum alloy ingot and conveyor belt aluminum alloy support extrusion die. The heating temperature of the extrusion cylinder is 430~440℃, the heating temperature of the die is 460~465℃, the heating temperature of the aluminum alloy ingot is 520~525℃, the extrusion speed in S4 is 12.5m / min, and aluminum alloy extrusion is obtained by extruding the aluminum alloy ingot.

[0062] S5. Quenching: The process parameters for the quenching step are: quenching temperature 500℃, quenching temperature 60℃, and cooling rate 105℃ / min.

[0063] Stretch straightening: The workpiece temperature for stretch straightening is 45℃; the stretching rate is calculated as the percentage of the difference in length of the extruded part before and after stretching relative to the length of the extruded part before stretching, and the stretching rate is 1.25%; sawing;

[0064] Aging: The aging process parameters for aluminum alloy extrusions are: aging temperature 145±3℃, aging time 12h, resulting in an aluminum alloy bracket with a wall thickness of 4mm.

[0065] The comparative aluminum alloy bracket has a localized blackening on its surface and a small number of overheated bubbles. The finished aluminum alloy bracket has a tensile strength of 221 MPa, a yield strength of 186 MPa, an elongation after fracture of 15.2%, and a hardness of 96 HV.

[0066] The examples and comparative examples show that adding a predetermined amount of Zr, Nb, and Ga to the aluminum alloy forms fine dispersions distributed throughout the matrix alloy, increasing the resistance to dislocation movement and improving the alloy's thermal stability and corrosion resistance. This is manifested in the fact that, at the higher extrusion heating temperature of Example 1, the aluminum alloy support surface is smooth, with a uniform color and no overheated bubbles. Increasing the extrusion heating temperature helps reduce extrusion energy consumption, improves the production efficiency of extrusion and the aluminum alloy support, and enhances the solid solution effect. Furthermore, by optimizing the aging temperature and quenching cooling rate, faster precipitation and dispersion of the matrix alloy are ensured, resulting in a uniform distribution of the dispersions, which is beneficial for improving the mechanical properties of the aluminum alloy, such as tensile strength and yield strength.

[0067] The above description is only a preferred embodiment of the present invention. It should be noted that for those skilled in the art, several improvements and modifications can be made without departing from the technical principles of the present invention, and these improvements and modifications should also be considered within the scope of protection of the present invention.

Claims

1. An extrusion forming process for aluminum alloy profiles, characterized in that, Includes the following steps: S1, raw aluminum ingots and master alloys are prepared according to the weight percentage of the constituent elements of the aluminum alloy: Mg: 0.55%~0.65%, Si: 0.4%~0.5%, Fe: 0.1%~0.2%, Zr: 0.01%~0.04%, Nb: 0.02%~0.05%, Ga: 0.01%~0.03%, Mn: <0.1%, C <0.1%, with the balance being aluminum and unavoidable impurities; S2: Transfer aluminum ingots and aluminum alloy raw materials into a melting furnace to melt into liquid aluminum alloy. After refining, degassing and removing impurities, melt the liquid aluminum alloy into aluminum alloy ingots. S3: The aluminum alloy ingot obtained by homogenization heat treatment S2 is heated to 470-490℃ and held for 3-5 hours, then heated to 565-580℃ and held for 7-10 hours, and then cooled to obtain homogenized aluminum alloy ingot. S4: Heating the extrusion cylinder, aluminum alloy ingot and mold, the heating temperature of the aluminum alloy ingot is 520~535℃, extruding the aluminum alloy ingot to obtain aluminum alloy extrusions; S5. The aluminum alloy workpiece is obtained by quenching, straightening, sawing and aging in sequence. The extrusion speed in S4 is 16–19 m / min; the heating temperature of the extrusion cylinder is 400–450℃; and the heating temperature of the die is 460–480℃. The process parameters for the quenching step are: quenching temperature 500-510℃, quenching temperature <70℃, and cooling rate 100-120℃ / min. The workpiece temperature after tension straightening is below 50℃; the stretching rate is calculated as the percentage of the difference in length of the extruded part before and after stretching to the length of the extruded part before stretching, and the stretching rate is 1.2% to 1.5%. The aging process parameters for aluminum alloy extrusions are: aging temperature 140~155℃, aging time 10~15h.

2. The extrusion forming process for aluminum alloy profiles according to claim 1, characterized in that, The master alloys of S1 include aluminum-zirconium-carbon master alloy, aluminum-niobium master alloy, and aluminum-gallium master alloy.

3. The extrusion forming process for aluminum alloy profiles according to claim 1, characterized in that, The weight percentages of the constituent elements in the aluminum alloy are as follows: Mg: 0.55%–0.6%, Si: 0.40%–0.46%, Fe: 0.1%–0.16%, Zr: 0.01%–0.03%, Nb: 0.02%–0.05%, Ga: 0.01%–0.02%, Mn: <0.05%, C <0.05%, with the balance being aluminum and unavoidable impurities. The sum of the weight percentages of Zr and Nb is not greater than 0.07%.

4. The extrusion forming process for aluminum alloy profiles according to claim 2, characterized in that, The mass percentage of carbon in aluminum-zirconium-carbon master alloys is no more than 0.15%, and the mass percentage of zirconium is 5% to 10%; the aluminum-niobium master alloy is AlNb50; and the aluminum-gallium master alloy is AlGa10.

5. The extrusion forming process for aluminum alloy profiles according to claim 1, characterized in that, The cooling rate for homogenization heat treatment in S3 is 8–11 °C / min.