Aluminum profile capable of improving exfoliation corrosion resistance and casting and heat treatment process thereof

Abstract

The aluminum profile comprises, by mass, 0.60%-0.7% of Si, 0.10%-0.15% of Fe, 0.8%-0.12% of Cu, 0.15%-0.25% of Mn, 0.55%-0.65% of Mg, 0.14%-0.2% of Cr, 0.15%-0.003% of Zn, 0.03%-0.06% of Ti, smaller than or equal to 0.01% of Pb, smaller than or equal to 0.15% of the total content of other impurity elements and the balance Al, the alkali metal content Na is smaller than or equal to 0.0004%, the alkali metal content Ca is smaller than or equal to 0.0002%, and the hydrogen content is 0.15 ml / 100 g. The corrosion resistance of the 6005A aluminum alloy material is improved by reasonably adjusting the proportion of chemical components and the casting technological process, the corrosion resistance can be easily achieved through existing domestic aluminum alloy smelting and casting equipment, and the exfoliation corrosion resistance of the finally obtained aluminum alloy profile is obviously improved through the aluminum alloy with optimized components.

Description

Technical Field

[0001] This invention relates to the field of aluminum alloy processing, and in particular to an aluminum profile with improved resistance to spalling corrosion and its casting and heat treatment processes. Background Technology

[0002] With the rapid development of the national economy, urban population density is gradually increasing. Due to the advantages of subway transportation, such as large passenger capacity, high speed, safety, punctuality, low pollution, low energy consumption, convenience, and comfort, rail transit has developed rapidly. Subways have become the most important mode of transportation in cities, carrying a very large passenger flow; therefore, the safety and reliability of subway vehicles themselves are of paramount importance. The performance testing of subway profiles has also become more stringent.

[0003] Aluminum alloys have low density but high strength, approaching or exceeding that of high-quality steel. They also possess good plasticity, allowing them to be processed into various profiles. Furthermore, they exhibit excellent electrical and thermal conductivity and high fatigue resistance, making them widely used in industry, second only to steel in terms of usage. They are extensively used in aerospace, automotive, machinery manufacturing, shipbuilding, and chemical industries. Subway profiles are also manufactured using aluminum alloys. However, the existing 6005A aluminum alloy profiles produced have relatively low resistance to exfoliation corrosion, failing to meet the high corrosion resistance requirements of rail transit. Summary of the Invention

[0004] The technical problem to be solved by the present invention is to overcome the shortcomings of the prior art and improve the aluminum alloy profiles and their casting and heat treatment processes by reasonably adjusting the chemical composition ratio, casting process and heat treatment process.

[0005] To solve the above-mentioned technical problems, the present invention provides the following technical solution: An aluminum profile with improved corrosion resistance has the following mass percentages: Si: 0.60-0.7%, Fe: 0.10-0.15%, Cu: 0.08-0.12%, Mn: 0.15-0.25%, Mg: 0.5-0.65%, Cr: 0.14-0.2%, Zn: 0.015-0.003%, Ti: 0.03-0.06%, Pb ≤ 0.01%, total content of other impurity elements ≤ 0.15%, balance is Al, and hydrogen content is 0.15 ml / 100 g.

[0006] Furthermore, the other impurity elements include Be, Zr, B, Na, Ca, V and Ni, wherein the alkali metal content is Na≤0.0004% and Ca≤0.0002%.

[0007] A casting and heat treatment process for aluminum profiles to improve corrosion resistance includes the following steps: Step 1: Add aluminum ingots, heat to 550-570℃, continue heating until completely melted, then let stand for at least 20 minutes, then gradually increase the temperature to 710-750℃ and maintain this temperature for at least 15 minutes; Step Two: Add refining agent to the molten aluminum from Step One and perform three refining processes: (1) First refining: When the temperature of the aluminum liquid reaches 710-720℃, open the argon valve and add the refining agent at the same time. Place the refining agent in the refining vessel and put it at the bottom of the furnace. The reaction products are insoluble in the aluminum alloy melt, forming bubbles and playing a purifying role in the process of floating to the surface of the metal liquid. The formed bubbles should be 50-80mm above the liquid surface. Adjust the air flow and move slowly to carry out refining. The refining time is 15 minutes. (2) Second refining: Repeat the steps in (1); refining time 15 minutes; (3) Third refining: Repeat the action in (1); refining time 10 minutes; Step 3: Let the molten aluminum, which has been refined three times, stand for 40 minutes and remove the slag; Step 4: After slag removal, maintain the temperature of the molten aluminum at 700-715℃ and pour it into the casting mold at a speed of 42mm / min to form a 900mm casting. Turn on the air compressor in the air duct for air cooling for 2 hours to reduce the temperature to 200℃. After completion, heat the casting to 565℃. The heating process should be completed within 4 hours. After reaching the temperature, hold it at that temperature for 12 hours. After completion, place it in a designated location to cool naturally to room temperature. Step 5: Extrusion molding; the cast ingot is transferred to a horizontal forward extrusion press and heated using a common frequency heating rate; the head is heated to 495-505℃ and the tail to 485-495℃, and extrusion is carried out at an extrusion speed of 0.7-0.9mm / s. Online quenching is performed using water standing waves. After extrusion, the profile passes through a water tank, and the temperature drops to 40℃±5℃; it is then placed on a material bed to cool to room temperature. Step Six: Transfer to the heating furnace for heat treatment. Heate once at a temperature of 175℃±5℃ and maintain the temperature for 8 hours. After completion, open the furnace and discharge the material. Place it in a designated location to cool naturally to room temperature. Step 7: Second heating, heating temperature is 100℃±5, maintain the temperature for 12 hours, remove from the furnace and air cool to room temperature to obtain the finished aluminum alloy profile.

[0008] Furthermore, the elemental mass percentages in the aluminum ingot are consistent with the mass percentages of the aluminum profile in claim 2, and the refining agent used in the three refining processes is the same substance, including: sodium nitrate, graphite powder, sodium chloride, and refractory brick chips. Furthermore, in step three, during slag removal, the slag is manually removed using a rake, and the surface of the melt is visually inspected to ensure there is no floating slag.

[0009] Furthermore, in step five, the heated casting rod is picked up by a robotic arm and placed on a pushing platform. After passing through a ring peeling machine, the casting rod is peeled to a thickness of 4mm. The casting rod is then pushed to a set position on the rod feeding machine by a pusher. The extruder opens the extrusion cylinder, retracts the extrusion rod, and the extruder's main control computer calls for the rod. The rod feeding machine lifts the casting rod and sends it to the set position on the extrusion cylinder. The extrusion rod advances to press the casting rod, while the extrusion cylinder advances to close the extrusion cylinder. A given extrusion speed is given, and the extrusion rod pushes the casting rod into the mold, resulting in the finished product.

[0010] The beneficial effects of this invention are as follows: This invention improves the corrosion resistance of 6005A aluminum alloy by rationally adjusting the chemical composition ratio and casting process. It is easily achieved using existing domestic aluminum alloy smelting and casting equipment. The use of aluminum alloy with optimized composition significantly improves the exfoliation corrosion resistance of the final aluminum alloy profile.

[0011] To make the above and other objects, features and advantages of the present invention more apparent and understandable, preferred embodiments are described below in detail with reference to the accompanying drawings. Attached Figure Description

[0012] To more clearly illustrate the technical solutions in this invention or the prior art, the accompanying drawings used in the description of the embodiments will be briefly introduced below. Obviously, the drawings described below are only some schematic diagrams of this invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0013] Figure 1 Before and after comparison of product sample 1 after adjustments to the chemical composition, casting and heat treatment processes of aluminum profiles; Figure 2 Before and after comparison of product sample 2, showing the chemical composition, casting and heat treatment processes of aluminum profiles after adjustments; Figure 3 Before and after comparison of sample 3 of aluminum profiles with no adjustment to chemical composition, casting and heat treatment processes; Figure 4 Table 1 shows the experimental data of the exfoliation corrosion test conducted on unadjusted aluminum profiles and adjusted aluminum profiles (aluminum profiles obtained by combining Examples 1 to 9 and Example 10) using the test methods specified in GB / T22639-2022. Figure 5 Table 2 shows the experimental data for the exfoliation corrosion test conducted on unadjusted aluminum profiles and adjusted aluminum profiles (aluminum profiles obtained by combining Examples 1 to 9 and Example 10) using the test methods specified in GB / T22639-2022. Detailed Implementation

[0014] The following will refer to the appendix. Figure 1-3 Embodiments of the invention will be described in more detail below. While some embodiments of the invention are shown in the accompanying drawings, it should be understood that the invention can be implemented in various forms and should not be construed as limited to the embodiments set forth herein. Rather, these embodiments are provided to provide a more thorough and complete understanding of the invention. It should be understood that the accompanying drawings and embodiments are for illustrative purposes only and are not intended to limit the scope of protection of the invention.

[0015] In this invention, unless otherwise explicitly specified and limited, the terms "installation", "setting", "connection", "fixing", "screw connection", etc., should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral part; they can refer to a mechanical connection, a direct connection, or an indirect connection through an intermediate medium. Those skilled in the art can understand the specific meaning of the above terms in this invention according to the specific circumstances.

[0016] The names of the messages or information exchanged between the multiple devices in the embodiments of the present invention are for illustrative purposes only and are not intended to limit the scope of these messages or information. Example 1

[0017] An aluminum profile with improved corrosion resistance comprises the following components (by mass percentage): Si: 0.65%, Fe: 0.14%, Cu: 0.08%, Mn: 0.16%, Mg: 0.54%, Cr: 0.14%, Zn: 0.015%, Ti: 0.03%, Pb: 0.01%, total content of Be, Zr, B, Na, Ca, V, and Ni: 0.15%, with the balance being Al, wherein the alkali metal content is Na: 0.0004%, Ca: 0.0002%, and the hydrogen content is 0.15 ml / 100 g. Example 2

[0018] An aluminum profile with improved corrosion resistance comprises the following components (by mass percentage): Si: 0.65%, Fe: 0.14%, Cu: 0.08%, Mn: 0.15%, Mg: 0.54%, Cr: 0.15%, Zn: 0.015%, Ti: 0.03%, Pb: 0.01%, total content of Be, Zr, B, Na, Ca, V, and Ni: 0.15%, with the balance being Al, wherein the alkali metal content is Na: 0.0004%, Ca: 0.0002%, and the hydrogen content is 0.15 ml / 100 g. Example 3

[0019] An aluminum profile with improved corrosion resistance comprises the following components (by mass percentage): Si: 0.65%, Fe: 0.14%, Cu: 0.08%, Mn: 0.19%, Mg: 0.54%, Cr: 0.14%, Zn: 0.015%, Ti: 0.03%, Pb: 0.01%, total content of Be, Zr, B, Na, Ca, V, and Ni: 0.15%, with the balance being Al, wherein the alkali metal content is Na: 0.0004%, Ca: 0.0002%, and the hydrogen content is 0.15 ml / 100 g. Example 4

[0020] An aluminum profile with improved corrosion resistance comprises the following components (by mass percentage): Si: 0.67%, Fe: 0.15%, Cu: 0.09%, Mn: 0.18%, Mg: 0.58%, Cr: 0.16%, Zn: 0.019%, Ti: 0.04%, Pb: 0.01%, total content of Be, Zr, B, Na, Ca, V, and Ni: 0.15%, balance being Al, wherein the alkali metal content is Na: 0.0004%, Ca: 0.0002%, and the hydrogen content is 0.15 ml / 100 g. Example 5

[0021] An aluminum profile with improved corrosion resistance comprises the following components (by mass percentage): Si: 0.68%, Fe: 0.15%, Cu: 0.095%, Mn: 0.2%, Mg: 0.59%, Cr: 0.17%, Zn: 0.022%, Ti: 0.045%, Pb: 0.01%, total content of Be, Zr, B, Na, Ca, V, and Ni: 0.15%, balance being Al, wherein the alkali metal content is Na: 0.0004%, Ca: 0.0002%, and the hydrogen content is 0.15 ml / 100 g. Example 6

[0022] An aluminum profile with improved corrosion resistance comprises the following components (by mass percentage): Si: 0.69%, Fe: 0.16%, Cu: 0.1%, Mn: 0.22%, Mg: 0.6%, Cr: 0.18%, Zn: 0.026%, Ti: 0.05%, Pb: 0.01%, total content of Be, Zr, B, Na, Ca, V, and Ni: 0.15%, balance being Al, wherein the alkali metal content is Na: 0.0004%, Ca: 0.0002%, and the hydrogen content is 0.15 ml / 100 g. Example 7

[0023] An aluminum profile with improved corrosion resistance comprises the following components (by mass percentage): Si: 0.7%, Fe: 0.17%, Cu: 0.11%, Mn: 0.25%, Mg: 0.62%, Cr: 0.17%, Zn: 0.03%, Ti: 0.06%, Pb: 0.01%, total content of Be, Zr, B, Na, Ca, V, and Ni: 0.15%, with the balance being Al, wherein the alkali metal content is Na: 0.0004%, Ca: 0.0002%, and the hydrogen content is 0.15 ml / 100 g. Example 8

[0024] An aluminum profile with improved corrosion resistance comprises the following components (by mass percentage): Si: 0.7%, Fe: 0.17%, Cu: 0.11%, Mn: 0.22%, Mg: 0.62%, Cr: 0.2%, Zn: 0.03%, Ti: 0.06%, Pb: 0.01%, total content of Be, Zr, B, Na, Ca, V, and Ni: 0.15%, with the balance being Al, wherein the alkali metal content is Na: 0.0004%, Ca: 0.0002%, and the hydrogen content is 0.15 ml / 100 g. Example 9

[0025] An aluminum profile with improved corrosion resistance comprises the following components (by mass percentage): Si: 0.7%, Fe: 0.17%, Cu: 0.11%, Mn: 0.25%, Mg: 0.62%, Cr: 0.18%, Zn: 0.03%, Ti: 0.06%, Pb: 0.01%, total content of Be, Zr, B, Na, Ca, V, and Ni: 0.15%, with the balance being Al, wherein the alkali metal content is Na: 0.0004%, Ca: 0.0002%, and the hydrogen content is 0.15 ml / 100 g. Example 10

[0026] A casting and heat treatment process for aluminum profiles to improve corrosion resistance includes the following steps: Step 1: Add aluminum ingots, heat to 550-570℃, continue heating until completely melted, then let stand for at least 20 minutes, then gradually increase the temperature to 710-750℃ and maintain this temperature for at least 15 minutes; The elemental mass percentages in the aluminum ingots are consistent with those in Example 1, Example 2, Example 3, Example 4, Example 5, Example 6, Example 7, Example 8, or Example 9.

[0027] Step 2: Add a refining agent to the molten aluminum from Step 1 and refine it three times. The refining agent is a mixture of sodium nitrate, graphite powder, sodium chloride and refractory brick chips.

[0028] (1) First refining: When the temperature of the aluminum liquid reaches 710-720℃, open the argon valve and add the refining agent at the same time. Place the refining agent in the refining vessel and put it at the bottom of the furnace. The reaction products are insoluble in the aluminum alloy melt, forming bubbles and playing a purifying role in the process of floating to the surface of the metal liquid. The formed bubbles should be 50-80mm above the liquid surface. Adjust the air flow and move slowly to carry out refining. The refining time is 15 minutes. (2) Second refining: Repeat the steps in (1); refining time 15 minutes; (3) Third refining: Repeat the action in (1); refining time 10 minutes; Step 3: Let the refined aluminum liquid stand for 40 minutes and remove the slag. When removing the slag, manually operate with a rake to remove the slag, and visually inspect the surface of the melt to ensure there is no floating slag. Step 4: After slag removal, maintain the temperature of the molten aluminum at 700-715℃ and pour it into the casting mold at a speed of 42mm / min to form a 900mm casting. Turn on the air compressor in the air duct for air cooling for 2 hours to reduce the temperature to 200℃. After completion, heat the casting to 565℃. The heating process should be completed within 4 hours. After reaching the temperature, hold it at that temperature for 12 hours. After completion, place it in a designated location to cool naturally to room temperature. Step 5: Extrusion Molding; The cast ingot is transferred to a horizontal forward extrusion press and heated using a common frequency heating system; the head is heated to 495-505℃, and the tail to 485-495℃. The heated ingot is then picked up by a robotic arm and placed on a pushing platform. It passes through a ring-shaped peeling machine to peel off a 4mm layer. The ingot is then pushed to a set position on the feeding machine by a pusher. The extrusion press opens the extrusion cylinder, retracts the extrusion rod, and the extrusion press main control computer calls for the ingot. The feeding machine lifts the ingot and sends it to the set position on the extrusion cylinder. The extrusion rod advances to press the ingot, while the extrusion cylinder advances to close it. A given extrusion speed is given, and the extrusion rod pushes the ingot into the mold, resulting in the extruded material. Extrusion is performed at a speed of 0.7-0.9mm / s. Online quenching uses water standing waves. After extrusion, the profile passes through a water tank, where the temperature drops to 40℃±5℃. It is then placed on a material bed to cool to room temperature. Step Six: Transfer to the heating furnace for heat treatment. Heate once at a temperature of 175℃±5℃ and maintain the temperature for 8 hours. After completion, open the furnace and discharge the material. Place it in a designated location to cool naturally to room temperature. Step 7: Second heating, heating temperature is 100℃±5, maintain the temperature for 12 hours, remove from the furnace and air cool to room temperature to obtain the finished aluminum alloy profile.

[0029] Exfoliation corrosion tests were conducted on unadjusted aluminum profiles and adjusted aluminum profiles (aluminum profiles obtained by combining Examples 1 to 9 with Example 10) using the test methods specified in GB / T22639-2022. The experimental data are shown in the table below. Figure 4-5As shown.

[0030] The experimental results above show that by reasonably adjusting the chemical composition ratio and casting process in this technical solution, the corrosion resistance of 6005A aluminum alloy can be improved. This can be easily achieved using existing domestic aluminum alloy smelting and casting equipment. The use of aluminum alloy with optimized composition significantly improves the exfoliation corrosion resistance of the final aluminum alloy profile.

[0031] Note that the above description is merely a preferred embodiment of the present invention and the technical principles employed. Those skilled in the art will understand that the present invention is not limited to the specific embodiments described herein, and various obvious changes, readjustments, and substitutions can be made without departing from the scope of protection of the present invention. Therefore, although the present invention has been described in detail through the above embodiments, the present invention is not limited to the above embodiments, and may include many other equivalent embodiments without departing from the concept of the present invention, the scope of which is determined by the scope of the appended claims.

Claims

1. An aluminum profile with improved corrosion resistance, characterized in that, Its mass percentages are as follows: Si: 0.60-0.7%, Fe: 0.10-0.15%, Cu: 0.08-0.12%, Mn: 0.15-0.25%, Mg: 0.5-0.65%, Cr: 0.14-0.2%, Zn: 0.015-0.003%, Ti: 0.03-0.06%, Pb ≤ 0.01%, total content of other impurity elements ≤ 0.15%, balance is Al, and hydrogen content is 0.15 ml / 100 g.

2. The aluminum profile with improved corrosion resistance according to claim 1, characterized in that: The other impurity elements include Be, Zr, B, Na, Ca, V and Ni, wherein the alkali metal content is Na≤0.0004% and Ca≤0.0002%.

3. A casting and heat treatment process for aluminum profiles to improve corrosion resistance, comprising the following steps: Step 1: Add aluminum ingots, heat to 550-570℃, continue heating until completely melted, then let stand for at least 20 minutes, then gradually increase the temperature to 710-750℃ and maintain this temperature for at least 15 minutes; Step Two: Add refining agent to the molten aluminum from Step One and refine it three times: (1) First refining: When the temperature of the aluminum liquid reaches 710-720℃, open the argon valve and add the refining agent at the same time. Place the refining agent in the refining vessel and put it at the bottom of the furnace. The reaction products are insoluble in the aluminum alloy melt, forming bubbles and playing a purifying role in the process of floating to the surface of the metal liquid. The formed bubbles should be 50-80mm above the liquid surface. Adjust the air flow and move slowly to carry out refining. The refining time is 15 minutes. (2) Second refining: Repeat the steps in (1); refining time 15 minutes; (3) Third refining: Repeat the action in (1); refining time 10 minutes; Step 3: Let the molten aluminum, which has been refined three times, stand for 40 minutes and remove the slag; Step 4: After slag removal, maintain the temperature of the molten aluminum at 700-715℃ and pour it into the casting mold at a speed of 42mm / min to form a 900mm casting. Turn on the air compressor in the air duct for air cooling for 2 hours to reduce the temperature to 200℃. After completion, heat the casting to 565℃. The heating process should be completed within 4 hours. After reaching the temperature, hold it at that temperature for 12 hours. After completion, place it in a designated location to cool naturally to room temperature. Step 5: Extrusion molding; the cast ingot is transferred to a horizontal forward extrusion press and heated using a common frequency heating rate; the head is heated to 495-505℃ and the tail to 485-495℃, and extrusion is carried out at an extrusion speed of 0.7-0.9mm / s. Online quenching is performed using water standing waves. After extrusion, the profile passes through a water tank, and the temperature drops to 40℃±5℃; it is then placed on a material bed to cool to room temperature. Step Six: Transfer to the heating furnace for heat treatment. Heate once at a temperature of 175℃±5℃ and maintain the temperature for 8 hours. After completion, open the furnace and discharge the material. Place it in a designated location to cool naturally to room temperature. Step 7: Second heating, heating temperature is 100℃±5, maintain the temperature for 12 hours, remove from the furnace and air cool to room temperature to obtain the finished aluminum alloy profile.

4. The aluminum profile casting and heat treatment process for improving corrosion resistance according to claim 3, characterized in that: The mass percentage of elements in the aluminum ingot is consistent with the mass percentage of the aluminum profile in claim 2. The refining agent used in the three refining processes is the same substance, which includes sodium nitrate, graphite powder, sodium chloride, and refractory brick chips.

5. The aluminum profile casting and heat treatment process for improving corrosion resistance according to claim 3, characterized in that: In step three, the slag is removed manually using a rake, and the surface of the melt is visually inspected to ensure there is no floating slag.

6. The aluminum profile casting and heat treatment process for improving corrosion resistance according to claim 4 or 5, characterized in that: in In step five, the heated casting rod is picked up by a robotic arm and placed on a pushing platform. It then passes through a ring peeling machine to peel off the outer layer of the casting rod to a thickness of 4mm. The casting rod is then pushed to a set position on the rod feeder by a pusher. The extruder opens the extrusion cylinder and retracts the extrusion rod. The extruder's main control computer calls for the rod, and the rod feeder lifts the casting rod and sends it to the set position on the extrusion cylinder. The extrusion rod advances to press the casting rod, while the extrusion cylinder advances to close the extrusion cylinder. A given extrusion speed is given, and the extrusion rod pushes the casting rod into the mold, resulting in the finished product.

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