A Short-Process Preparation Method for T3-State Al-Cu-Mg-Mn Alloy Plates

Abstract

This invention relates to a short-process preparation method for T3-state Al-Cu-Mg-Mn alloy sheets, and is situated in the field of aluminum alloy preparation technology. The invention addresses the technical problems of time-consuming and costly homogenization annealing, as well as the difficulty in achieving both desirable and undesirable performance characteristics in traditional processes. The method involves raw material weighing and batching, alloy smelting, melt refining, alloy casting, direct heating and rolling of ingots, solution treatment, and aging. By strictly controlling Fe and Si impurities to avoid the formation of coarse primary phases, precisely regulating Cu content to balance strengthening and corrosion resistance, increasing Mn content to compensate for strength loss, and eliminating homogenization annealing, the production cycle is shortened by more than 30%, and manufacturing costs are reduced by more than 20%. The prepared T3-state sheets meet aerospace standards in terms of mechanical properties and corrosion resistance, demonstrating promising prospects for industrial application. This invention is used to prepare T3-state Al-Cu-Mg-Mn alloy sheets.

Description

Technical Field

[0001] This invention relates to the field of aluminum alloy preparation technology. Background Technology

[0002] Al-Cu-Mg-Mn aluminum alloys are high-strength hard aluminum alloys with high specific strength, high toughness, good processing and forming properties, and heat-treatable strengthening characteristics. They are core raw materials for load-bearing structural components and thin-walled structural components in high-end equipment fields such as aerospace and rail transportation. Among them, Al-Cu-Mg-Mn alloy plates in the T3 state (solution treatment followed by natural aging) are widely used in the manufacture of thin-walled structures and load-bearing components in aerospace due to their excellent strength, toughness, and processing performance. Their performance directly affects the reliability and service life of the equipment.

[0003] In the traditional T3-state Al-Cu-Mg-Mn alloy sheet preparation process, a lengthy homogenization annealing process is required after the ingot is cast. The main purpose of this process is to eliminate component segregation inside the ingot and break up the coarse compound phases remaining in the as-cast structure, laying the foundation for subsequent rolling and heat treatment processes. However, the homogenization annealing process usually lasts 12 to 14 hours, which is not only time-consuming but also consumes a large amount of heat energy, significantly increasing the production cycle and manufacturing costs. At the same time, even small fluctuations in the homogenization annealing process parameters can easily lead to poor homogenization of the as-cast structure, thereby affecting the mechanical property stability of the sheet material.

[0004] Furthermore, traditional processes have many shortcomings in alloy composition control and process parameter settings, making it difficult to achieve optimal product performance: First, the control of impurity elements such as Fe and Si is lax, typically with Si ≤ 0.5% and Fe ≤ 0.5%. These impurities easily form coarse Al-Si and Al-Fe-Si primary phases in the as-cast structure. These primary phases are hard and brittle, and are difficult to completely eliminate during subsequent rolling, solution treatment, and other heating processes, which severely deteriorates the mechanical and processing properties of the sheet metal. Second, the addition of Cu is too high. Although it can improve the strength of the alloy to a certain extent, excessive Cu will form coarse Al2Cu phases with Al, significantly deteriorating the corrosion resistance of the alloy and making the sheet metal susceptible to intergranular corrosion, failing to meet the stringent corrosion resistance requirements of the aerospace field. Third, the optimization of process parameters is insufficient, such as excessively long melt refining time, imperfect casting filtration and degassing processes, and unreasonable ingot heating and holding time. This not only further increases production costs but also easily leads to defects such as porosity and inclusions inside the ingot, affecting the final performance of the sheet metal.

[0005] In recent years, the industry has attempted to address these issues by simplifying processes and adjusting compositions, but a systematic technical solution has not yet been developed. Either the homogenization annealing process is simply eliminated without simultaneous optimization of the alloy composition, resulting in unresolved defects in the as-cast structure and substandard plate performance; or only the content of a single element or a single process parameter is adjusted, failing to achieve a synergistic match between composition and process, making it difficult to balance plate strength, corrosion resistance, and production efficiency. Therefore, developing a process for the efficient, low-cost, and high-performance preparation of T3-state Al-Cu-Mg-Mn alloy plates by precisely controlling alloy composition, optimizing process parameters, and eliminating the homogenization annealing process has become a pressing technical challenge in this field. Summary of the Invention

[0006] This invention addresses the core technical problems of traditional processes, such as time-consuming and energy-intensive homogenization annealing, long production cycles and high costs, lax control of Fe and Si impurities leading to the formation of coarse primary phases and deterioration of plate properties, unreasonable addition of Cu making it difficult to balance strength and corrosion resistance, insufficient optimization of process parameters such as melt refining and casting affecting performance stability, and the inability to achieve a synergistic unity of short process, low cost and high performance and high stability.

[0007] This invention achieves efficient and low-cost preparation of T3-state Al-Cu-Mg-Mn alloy plates by precisely controlling the alloy composition and optimizing the preparation process parameters, eliminating the time-consuming and energy-intensive homogenization annealing process in traditional processes. The mechanical properties and corrosion resistance of the prepared plates meet the stringent requirements of the aerospace field and can be widely used in the manufacture of aerospace load-bearing structural components, thin-walled structural components, etc.

[0008] The core technical solution of this invention is to precisely control the alloy composition and optimize the preparation process parameters, eliminating the homogenization annealing step and achieving synergistic matching between composition and process. The alloy composition is precisely controlled by mass percentage as follows: Si ≤ 0.1%, Fe ≤ 0.15%, Cu: 3.4~4.0%, Mg: 1.2~1.8%, Mn: 0.45~0.70%, Ni ≤ 0.1%, Zn ≤ 0.25%, Ti: 0.02~0.12%, with individual impurities ≤ 0.05%, total impurities ≤ 0.20%, and the balance being Al, preferably Fe ≤ 0.12%, Cu: 3.5~3.8%, and Mn... Mn content: 0.55~0.65%, Ti: 0.05~0.09% to improve performance stability; the preparation process includes raw material weighing and batching, alloy melting, melt refining, alloy casting, direct heating and rolling of ingots, solution treatment and aging treatment. Each step has clear parameter control. The purity of raw materials is ≥99.9%. The preferred Mn content for aluminum-manganese and aluminum-titanium master alloys is 10% and the Ti content is 4%. Direct heating and rolling of ingots replaces homogenization annealing with reasonable temperature control and reduction rate. The water quenching cooling rate after solution treatment is preferably not less than 20℃ / s. Finally, a T3 state Al-Cu-Mg-Mn alloy plate that meets the requirements is prepared.

[0009] A short-process method for preparing T3 state Al-Cu-Mg-Mn alloy plates, specifically comprising the following steps:

[0010] I. Raw Material Weighing and Batching: Weigh the raw materials according to the mass percentage of the alloy composition. The raw materials include high-purity aluminum ingots, copper ingots, magnesium ingots, aluminum-manganese master alloys, and aluminum-titanium master alloys. The alloy composition, by mass percentage, is: Si≤0.1%, Fe≤0.15%, Cu: 3.4~4.0%, Mg: 1.2~1.8%, Mn: 0.45~0.70%, Ni≤0.1%, Zn≤0.25%, Ti: 0.02~0.12%, with individual impurities ≤0.05%, total impurities ≤0.20%, and the balance being Al.

[0011] II. Alloy smelting: Add the high-purity aluminum ingots weighed in step one to the smelting furnace and smelt them at 730℃~750℃. After they are completely melted, add aluminum-manganese master alloy and aluminum-titanium master alloy in sequence. Stir until they are completely melted, then add copper ingots and keep them warm for 15~20 minutes. Then add magnesium ingots and use electromagnetic stirring until the composition of the melt is uniform.

[0012] 3. Melt refining: Keep the temperature of the melt after melting in step 2 at 720℃~740℃, and refine it with Ar-Cl2 mixed gas for 10~15min, then let it stand for 20~30min.

[0013] IV. Alloy Casting: After the melt refined in step three is filtered through a 30ppi+50ppi double-layer ceramic filter and degassed in a dual-rotor degassing box, it is poured into the crystallizer. The casting temperature is controlled at 700℃~730℃ and the casting speed is 40~60mm / min. Alloy ingots with a thickness of 420mm, a width of 1320mm, and a length of 5000~6500mm are cast.

[0014] V. Direct heating and rolling of ingots: After milling the surface of the alloy ingots obtained in step 4, directly heat them to 400-430℃, hold them at that temperature for 6-10 hours, and then roll them. During the rolling process, the plate temperature is ≥380℃ to obtain plate billets.

[0015] VI. Solution treatment and aging treatment: The plate blank obtained in step 5 is solution treated at 460~500℃ for 1~3h, then immediately water quenched, and then naturally aged at room temperature for more than 72h to obtain the T3 state Al-Cu-Mg-Mn alloy plate.

[0016] Furthermore, the alloy composition described in step one, by mass percentage, is Fe ≤ 0.12%, Cu: 3.5~3.8%, Mg: 1.2~1.8%, Mn: 0.55~0.65%, Ti: 0.05~0.09%, with the balance being Al;

[0017] Furthermore, in step one, the Mn content in the aluminum-manganese master alloy is 10%, and the Ti content in the aluminum-titanium master alloy is 4%.

[0018] Furthermore, the stirring speed of the electromagnetic stirrer in step two is 300~400 r / min, and the stirring time is 8~12 min.

[0019] Further, in step three, the mixture is refined until the hydrogen content is ≤0.20mL per 100g of melt.

[0020] Furthermore, in step three, the volume ratio of argon to chlorine in the Ar-Cl2 mixed gas is (30-35):1.

[0021] Furthermore, the quenching transfer time in step five is ≤15s.

[0022] Furthermore, in step five, the single-pass reduction rate is controlled to be ≥15%, and the total reduction rate is ≥80%.

[0023] Furthermore, the cooling rate of water quenching after solution treatment in step six shall not be less than 20℃ / s.

[0024] Furthermore, a T3-state Al-Cu-Mg-Mn alloy sheet was obtained, with a tensile strength ≥425MPa, a yield strength ≥275MPa, an elongation ≥12%, and an intergranular corrosion level of 1.

[0025] This invention, through precise composition control and process optimization, eliminates the homogenization annealing step, achieving short-process, low-cost, and high-performance preparation of T3-state Al-Cu-Mg-Mn alloy plates, with the following significant advantages:

[0026] 1. Significantly improved production efficiency and reduced manufacturing costs: The homogenization annealing process, which takes 12 to 14 hours in the traditional process, is completely eliminated, and the melt refining time is shortened, reducing the overall production cycle by more than 30%. It saves a lot of heat energy consumption required for homogenization annealing, reduces the operating wear and maintenance costs of heating furnace equipment, and the simplified process also reduces the costs of manual operation and material management. Compared with the traditional process, the manufacturing cost is reduced by more than 20%, which has significant economic advantages and facilitates industrial mass production.

[0027] 2. Alloy composition optimization and synergistic performance improvement: By strictly controlling Fe ≤ 0.15% and Si ≤ 0.1%, the formation of coarse primary phases is avoided from the source, significantly improving the purity of the as-cast microstructure; precise control of Cu content (3.4~4.0%) balances strength and corrosion resistance; increasing Mn content (0.45~0.70%) compensates for strength loss, achieving the dual goals of "no reduction in strength and improved corrosion resistance". The prepared T3 state plates have a tensile strength ≥ 425 MPa, yield strength ≥ 275 MPa, elongation ≥ 12%, and intergranular corrosion rating of level 1, fully meeting the stringent requirements of the aerospace field.

[0028] 3. High process stability and improved product qualification rate: The optimized melt refining (double purification), casting, rolling and heat treatment process parameters are matched in a coordinated manner to reduce defects such as ingot porosity, inclusions and component segregation, and the microstructure uniformity of ingots and plates is significantly improved; after eliminating the homogenization annealing process, the impact of fluctuations in the parameters of this process on product performance is avoided, the product performance stability is greatly improved, and the qualification rate is increased to over 98%.

[0029] 4. Green and environmentally friendly, in line with industrial development trends: It reduces the energy consumption of high-temperature homogenization annealing, reduces pollutant emissions during the production process, and reduces energy consumption by more than 25% compared with traditional processes. It meets the energy conservation, emission reduction and green environmental protection requirements of modern industrial production and has good environmental benefits.

[0030] This invention is used to prepare Al-Cu-Mg-Mn alloy plates in the T3 state. Detailed Implementation

[0031] Specific Implementation Method 1: This implementation method provides a short-process preparation method for T3 state Al-Cu-Mg-Mn alloy plates, which is carried out according to the following steps:

[0032] I. Raw Material Weighing and Batching: Weigh the raw materials according to the mass percentage of the alloy composition. The raw materials include high-purity aluminum ingots, copper ingots, magnesium ingots, aluminum-manganese master alloys, and aluminum-titanium master alloys. The alloy composition, by mass percentage, is: Si≤0.1%, Fe≤0.15%, Cu: 3.4~4.0%, Mg: 1.2~1.8%, Mn: 0.45~0.70%, Ni≤0.1%, Zn≤0.25%, Ti: 0.02~0.12%, with individual impurities ≤0.05%, total impurities ≤0.20%, and the balance being Al.

[0033] II. Alloy smelting: Add the high-purity aluminum ingots weighed in step one to the smelting furnace and smelt them at 730℃~750℃. After they are completely melted, add aluminum-manganese master alloy and aluminum-titanium master alloy in sequence. Stir until they are completely melted, then add copper ingots and keep them warm for 15~20 minutes. Then add magnesium ingots and use electromagnetic stirring until the composition of the melt is uniform.

[0034] 3. Melt refining: Keep the temperature of the melt after melting in step 2 at 720℃~740℃, and refine it with Ar-Cl2 mixed gas for 10~15min, then let it stand for 20~30min.

[0035] IV. Alloy Casting: After the melt refined in step three is filtered through a 30ppi+50ppi double-layer ceramic filter and degassed in a dual-rotor degassing box, it is poured into the crystallizer. The casting temperature is controlled at 700℃~730℃ and the casting speed is 40~60mm / min. Alloy ingots with a thickness of 420mm, a width of 1320mm, and a length of 5000~6500mm are cast.

[0036] V. Direct heating and rolling of ingots: After milling the surface of the alloy ingots obtained in step 4, directly heat them to 400-430℃, hold them at that temperature for 6-10 hours, and then roll them. During the rolling process, the plate temperature is ≥380℃ to obtain plate billets.

[0037] VI. Solution treatment and aging treatment: The plate blank obtained in step 5 is solution treated at 460~500℃ for 1~3h, then immediately water quenched, and then naturally aged at room temperature for more than 72h to obtain the T3 state Al-Cu-Mg-Mn alloy plate.

[0038] Specific Implementation Method Two: This implementation method differs from Specific Implementation Method One in that the alloy composition in step one, by mass percentage, is Fe ≤ 0.12%, Cu: 3.5~3.8%, Mg: 1.2~1.8%, Mn: 0.55~0.65%, Ti: 0.05~0.09%, with the balance being Al. Everything else is the same as in Specific Implementation Method One.

[0039] Specific Implementation Method Three: This implementation method differs from Specific Implementation Method One or Two in that the Mn mass content in the aluminum-manganese master alloy described in step one is 10%, and the Ti mass content in the aluminum-titanium master alloy is 4%. Everything else is the same as in Specific Implementation Method One or Two.

[0040] Specific Implementation Method Four: This implementation method differs from Specific Implementation Methods One to Three in that the stirring speed of the electromagnetic stirrer in step two is 300~400 r / min, and the stirring time is 8~12 min. Everything else is the same as in Specific Implementation Methods One to Three.

[0041] Specific Implementation Method Five: This implementation method differs from Specific Implementation Methods One to Four in that step three involves refining the melt until the hydrogen content is ≤0.20mL per 100g. Everything else is the same as in Specific Implementation Methods One to Four.

[0042] Specific Implementation Method Six: This implementation method differs from Specific Implementation Methods One to Five in that the volume ratio of argon to chlorine in the Ar-Cl2 mixed gas described in step three is (30-35):1. Everything else is the same as in Specific Implementation Methods One to Five.

[0043] Specific Implementation Method Seven: This implementation method differs from Specific Implementation Methods One to Six in that the quenching transfer time in step five is ≤15s. Everything else is the same as in Specific Implementation Methods One to Six.

[0044] Specific Implementation Method Eight: This implementation method differs from Specific Implementation Methods One to Seven in that: in step five, the single-pass reduction rate is controlled to be ≥15%, and the total reduction rate is ≥80%. Everything else is the same as in Specific Implementation Methods One to Seven.

[0045] Specific Implementation Method Nine: This implementation method differs from Specific Implementation Methods One to Eight in that the cooling rate of water quenching after the solution treatment in step six is ​​not less than 20°C / s. Everything else is the same as in Specific Implementation Methods One to Eight.

[0046] Specific Implementation Method Ten: This implementation method differs from Specific Implementation Methods One through Nine in that it yields a T3-state Al-Cu-Mg-Mn alloy sheet with a tensile strength ≥425MPa, a yield strength ≥275MPa, an elongation ≥12%, and an intergranular corrosion rating of 1. All other aspects are the same as in Specific Implementation Methods One through Nine.

[0047] The scope of this invention is not limited to the above-described embodiments; a combination of one or more specific embodiments can also achieve the purpose of the invention.

[0048] Example

[0049] A short-process method for preparing T3 state Al-Cu-Mg-Mn alloy plates, specifically comprising the following steps:

[0050] I. Raw Material Weighing and Batching: Weigh the raw materials according to the mass percentage of the alloy composition. The raw materials include high-purity aluminum ingots, copper ingots, magnesium ingots, aluminum-manganese master alloy (Al-10%Mn), and aluminum-titanium master alloy (Al-4%Ti). The alloy composition, by mass percentage, is: Si≤0.1%, Fe≤0.12%, Cu: 3.5~3.8%, Mg: 1.2~1.8%, Mn: 0.55~0.65%, Ni≤0.1%, Zn≤0.25%, Ti: 0.05~0.09%, with individual impurities ≤0.05%, total impurities ≤0.20%, and the balance being Al.

[0051] II. Alloy smelting: Add the high-purity aluminum ingots weighed in step one to the smelting furnace and smelt them at 740℃. After they are completely melted, add aluminum-manganese master alloy and aluminum-titanium master alloy in sequence. Stir until they are completely melted, then add copper ingots and keep them warm for 18 minutes. Then add magnesium ingots and use electromagnetic stirring for 10 minutes at a stirring speed of 350 r / min until the melt composition is uniform.

[0052] 3. Melt refining: Keep the temperature of the melt after melting in step 2 at 730℃, use Ar-Cl2 mixed gas (argon to chlorine volume ratio 32:1) to refine for 12 minutes, until the hydrogen content in 100 grams of melt is ≤0.20 mL, and then let it stand for 25 minutes.

[0053] IV. Alloy Casting: The refined melt from step three is filtered through a 30ppi + 50ppi double-layer ceramic filter and degassed in a dual-rotor degassing box before being poured into the crystallizer. The casting temperature is controlled at 710℃ and the water flow rate at 30m³ / h. 3 / h, liquid level 85mm, casting speed 50mm / min, casting alloy ingots with a thickness of 420mm, a width of 1320mm, and a length of 5800mm;

[0054] V. Direct heating and rolling of ingots: After milling the surface of the alloy ingots obtained in step 4, directly heat them to 410℃, hold them at that temperature for 8 hours until the internal and external temperatures are uniform, and then roll them. The single-pass reduction rate is 18%, the total reduction rate is 85%, and the plate temperature is ≥380℃ during the rolling process to obtain plate billets.

[0055] VI. Solution treatment and aging: The plate blank obtained in step 5 is solution treated at 480℃ for 2 hours, then immediately water quenched (cooling rate ≥20℃ / s), with a quenching transfer time of 10s, and then naturally aged at room temperature for 80 hours to obtain the T3 state Al-Cu-Mg-Mn alloy plate.

[0056] The example yielded a T3 state Al-Cu-Mg-Mn alloy sheet with a tensile strength ≥425MPa, a yield strength ≥275MPa, an elongation ≥12%, and an intergranular corrosion level of 1.

Claims

1. A short-process preparation method for T3 state Al-Cu-Mg-Mn alloy plates, characterized in that... This method is specifically carried out in the following steps: I. Raw Material Weighing and Batching: Weigh the raw materials according to the mass percentage of the alloy composition. The raw materials include high-purity aluminum ingots, copper ingots, magnesium ingots, aluminum-manganese master alloys, and aluminum-titanium master alloys. The alloy composition, by mass percentage, is: Si≤0.1%, Fe≤0.15%, Cu: 3.4~4.0%, Mg: 1.2~1.8%, Mn: 0.45~0.70%, Ni≤0.1%, Zn≤0.25%, Ti: 0.02~0.12%, with individual impurities ≤0.05%, total impurities ≤0.20%, and the balance being Al. II. Alloy smelting: Add the high-purity aluminum ingots weighed in step one to the smelting furnace and smelt them at 730℃~750℃. After they are completely melted, add aluminum-manganese master alloy and aluminum-titanium master alloy in sequence. Stir until they are completely melted, then add copper ingots and keep them warm for 15~20 minutes. Then add magnesium ingots and use electromagnetic stirring until the composition of the melt is uniform.

3. Melt refining: Keep the temperature of the melt after melting in step 2 at 720℃~740℃, and refine it with Ar-Cl2 mixed gas for 10~15min, then let it stand for 20~30min. IV. Alloy Casting: After the melt refined in step three is filtered through a 30ppi+50ppi double-layer ceramic filter and degassed in a dual-rotor degassing box, it is poured into the crystallizer. The casting temperature is controlled at 700℃~730℃ and the casting speed is 40~60mm / min. Alloy ingots with a thickness of 420mm, a width of 1320mm, and a length of 5000~6500mm are cast. V. Direct heating and rolling of ingots: After milling the surface of the alloy ingots obtained in step 4, directly heat them to 400-430℃, hold them at that temperature for 6-10 hours, and then roll them. During the rolling process, the plate temperature is ≥380℃ to obtain plate billets. VI. Solution treatment and aging treatment: The plate blank obtained in step 5 is solution treated at 460~500℃ for 1~3h, then immediately water quenched, and then naturally aged at room temperature for more than 72h to obtain the T3 state Al-Cu-Mg-Mn alloy plate.

2. The short-process preparation method of T3 state Al-Cu-Mg-Mn alloy plate according to claim 1, characterized in that... The alloy composition described in step one, by mass percentage, is Fe ≤ 0.12%, Cu: 3.5~3.8%, Mg: 1.2~1.8%, Mn: 0.55~0.65%, Ti: 0.05~0.09%, with the balance being Al.

3. The short-process preparation method of T3 state Al-Cu-Mg-Mn alloy plate according to claim 1, characterized in that... In step one, the Mn content in the aluminum-manganese master alloy is 10%, and the Ti content in the aluminum-titanium master alloy is 4%.

4. The short-process preparation method of T3 state Al-Cu-Mg-Mn alloy plate according to claim 1, characterized in that... The stirring speed of the electromagnetic stirrer in step two is 300~400 r / min, and the stirring time is 8~12 min.

5. The short-process preparation method of T3 state Al-Cu-Mg-Mn alloy plate according to claim 1, characterized in that... Step 3: Refine until the hydrogen content in 100 grams of melt is ≤0.20 mL.

6. The short-process preparation method of T3 state Al-Cu-Mg-Mn alloy plate according to claim 1, characterized in that... In step three, the volume ratio of argon to chlorine in the Ar-Cl2 mixed gas is (30-35):

1.

7. The short-process preparation method of T3 state Al-Cu-Mg-Mn alloy plate according to claim 1, characterized in that... Step 5: Quenching and transfer time ≤ 15s.

8. The short-process preparation method of T3 state Al-Cu-Mg-Mn alloy plate according to claim 1, characterized in that... Step 5: Rolling control: Single pass reduction rate ≥ 15%, total reduction rate ≥ 80%.

9. The short-process preparation method of T3 state Al-Cu-Mg-Mn alloy plate according to claim 1, characterized in that... The cooling rate of water quenching after solution treatment in step six shall not be less than 20℃ / s.

10. A short-process preparation method for a T3 state Al-Cu-Mg-Mn alloy plate according to claim 1, characterized in that... The T3 state Al-Cu-Mg-Mn alloy sheet was obtained with tensile strength ≥425MPa, yield strength ≥275MPa, elongation ≥12%, and intergranular corrosion level 1.