Marine 6 series aluminum alloy profile and preparation method thereof

Abstract

The present invention relates to the field of aluminum alloy process technology, and in particular to a 6-series aluminum alloy profile for ship and a preparation method thereof. The 6-series aluminum alloy profile for ship is characterized in that the components and their weight percentages in the aluminum alloy profile are as follows: Si content is 0.9-1.5%; Fe content is ≤0.2%; Cu content is 0.2-0.9%; Mn content is 0.2-0.8%; Mg content is 0.9-1.3%; Zn content is 0.02-0.5%; Er content is 0.02-0.2%; Zr content is 0.02-0.2%; the total content of other impurity elements is ≤0.15%; and the balance is Al. The 6-series aluminum alloy profile for ship has high strength, corrosion resistance, weldability and fatigue resistance.

Description

Technical Field

[0001] The invention relates to the technical field of aluminum alloy processes, and in particular to a marine 6 series aluminum alloy profile and a preparation method thereof. Background Art

[0002] Aluminum alloys have the characteristics of low density, high specific strength and specific stiffness, good corrosion resistance, low maintenance cost, and good low-temperature performance. They have been widely used in marine engineering fields such as ships and offshore platforms. In the 1960s, 5xxx aluminum alloy plates and 6xxx aluminum alloy profiles began to be widely used as hulls and superstructures. Rich application experience has been accumulated, and a relatively complete marine aluminum alloy system and supporting theories and processing technologies have been established. The original hull and shipboard buildings use a large number of 6 series and improved aluminum alloy profiles, such as 6082. However, although the comprehensive performance is good, the mechanical properties are difficult to meet the growing demand for high-strength and corrosion-resistant comprehensive performance of marine cabin aluminum profiles. At the same time, improving the strength, corrosion resistance, welding and fatigue resistance of aluminum alloys is still an important research direction. The existing technology uses trace elements to balance the above properties, but due to the preparation method, it is impossible to prepare 6 series aluminum alloy profiles for ships.

[0003] In summary, it is urgent to solve the problem in the prior art that the introduction of trace elements increases the degree of alloying and thus makes it difficult for marine 6 series aluminum alloy profiles to have strength, corrosion resistance, welding and fatigue resistance. Summary of the invention

[0004] The present invention aims to solve the technical problem that the introduction of trace elements increases the alloying degree and thus makes it difficult for marine 6 series aluminum alloy profiles to have strength, corrosion resistance, welding and fatigue resistance.

[0005] In order to achieve the above-mentioned object, the first aspect of the present invention provides a marine 6 series aluminum alloy profile, wherein the components and their weight percentages in the aluminum alloy profile are:

[0006] Si content is 0.9-1.5%;

[0007] Fe content ≤ 0.2%;

[0008] Cu content is 0.2-0.9%;

[0009] Mn content is 0.2-0.8%;

[0010] Mg content is 0.9-1.3%;

[0011] Zn content is 0.02-0.5%;

[0012] Er content is 0.02-0.2%;

[0013] Zr content is 0.02-0.2%;

[0014] The total content of other impurity elements is ≤0.15%;

[0015] The balance is Al.

[0016] A second aspect of the present invention provides a method for preparing the above-mentioned marine 6 series aluminum alloy profile, wherein the preparation method comprises:

[0017] The aluminum alloy raw materials are melted at a melting temperature of 760-780°C, and electromagnetic stirring is combined with mechanical stirring, refining, casting, online degassing, filtering, and homogenization are performed, wherein the casting speed is 50-80 mm / min;

[0018] The aluminum alloy ingot after homogenization treatment is extruded, the working band width of the extrusion die is 3-4mm, and the slope angle of the diversion pit is 12-18 degrees;

[0019] The extruded aluminum alloy material is cooled by water, and the distance between the quenching tank and the front wall of the extrusion device is less than 300mm;

[0020] The quenched aluminum alloy material is subjected to thermal insulation aging using a single-stage aging system.

[0021] A third aspect of the present invention provides a marine 6 series aluminum alloy profile produced by the above-mentioned preparation method.

[0022] The beneficial effects of the present invention are:

[0023] (1) The marine 6 series aluminum alloy profile provided by the present invention has high strength, corrosion resistance, weldability and fatigue resistance.

[0024] (2) The preparation method provided by the present invention aims to solve the problem that the composition of the marine 6 series aluminum alloy profile is changed, the alloying degree is increased, and the processing is difficult, and the problems of high melt viscosity, poor fluidity, looseness, and increased slag inclusion tendency are solved.

[0025] (3) The three key technologies of the marine 6 series aluminum alloy profile provided by the present invention have achieved breakthroughs: the strength of the new type of cabin high-strength corrosion-resistant aluminum alloy extruded profile can match the welding performance, the exfoliation corrosion resistance of the extruded profile is improved, and the fatigue resistance of the extruded profile is improved. Finally, the yield strength ≥350MPa, tensile strength ≥390MPa, fatigue strength ≥200MPa, and exfoliation corrosion meet the requirements of GB / T122639-2008 EA grade new type of marine cabin high-strength corrosion-resistant aluminum alloy profile, making the product performance 10MPa higher than the tensile strength performance of 6110A aluminum alloy with similar composition. After laser welding with this profile, the tensile strength of the joint is ≥300MPa, and the joint strength is ≥0.76, which meets the comprehensive performance requirements of marine cabins for aluminum profiles of high strength, corrosion resistance, weldability, and fatigue resistance. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] Figure 1 This is a cross-sectional view of a 6 series aluminum alloy profile for marine use;

[0027] Figure 2 This is a high-magnification metallographic structure diagram of Example 1;

[0028] Figure 3 This is the exfoliation corrosion detection diagram of Example 1;

[0029] Figure 4 This is a high-magnification metallographic structure diagram of Example 2;

[0030] Figure 5 This is the exfoliation corrosion detection diagram of Example 2;

[0031] Figure 6 This is a high-magnification metallographic structure diagram of Example 3;

[0032] Figure 7 This is the exfoliation corrosion detection diagram of Example 3. DETAILED DESCRIPTION

[0033] The endpoints and any values ​​of the ranges disclosed in this article are not limited to the precise ranges or values, and these ranges or values ​​should be understood to include values ​​close to these ranges or values. For numerical ranges, the endpoint values ​​of each range, the endpoint values ​​of each range and the individual point values, and the individual point values ​​can be combined with each other to obtain one or more new numerical ranges, which should be considered as specifically disclosed in this article.

[0034] The 6 series aluminum alloy profiles used in the prior art for marine use are difficult to have strength, corrosion resistance, welding and fatigue resistance.

[0035] In the present invention, the inventors found that if Er and Zr are introduced into the marine 6 series aluminum alloy profile, the welding strength can be improved, and a specific preparation method is adopted, so that the marine 6 series aluminum alloy profile has alloy strength, corrosion resistance, fatigue resistance and welding performance.

[0036] To achieve this goal, the inventors tried to optimize the composition of each component and the preparation method of the marine 6 series aluminum alloy profile. The inventors found that the above-mentioned purpose can be achieved through specific composition of each component and preparation method.

[0037] To this end, the first aspect of the present invention provides a marine 6 series aluminum alloy profile, wherein the components and their weight percentages in the aluminum alloy profile are:

[0038] Si content is 0.9-1.5%;

[0039] Fe content ≤ 0.2%;

[0040] Cu content is 0.2-0.9%;

[0041] Mn content is 0.2-0.8%;

[0042] Mg content is 0.9-1.3%;

[0043] Zn content is 0.02-0.5%;

[0044] Er content is 0.02-0.2%;

[0045] Zr content is 0.02-0.2%;

[0046] The total content of other impurity elements is ≤0.15%;

[0047] The balance is Al.

[0048] In the present invention, the inventors found that according to the combination of the above components, the submicron / nanoscale Al3Er, Al3Zr precipitation phases, and Al6Mn precipitation phases can fully exert their role in inhibiting recrystallization during extrusion, promoting the precipitation of phases during artificial aging, and regulating the mechanism of the width of the grain boundary non-precipitation phase; Zr and Er elements are added to inhibit recrystallization or coarsening of grains, improve welding strength, and the β-Mg2Si phase and Al3Er phase present in the weld area after welding form fine dendrites and equiaxed crystals. The above components cooperate with each other to balance the alloy strength, corrosion resistance, fatigue resistance and welding performance.

[0049] Preferably, the Er content is controlled to be 0.12%, the Zr content is 0.12%, the Mn content is 0.5%, and the Cu content is 0.6%, so that the profile has high strength and excellent corrosion resistance.

[0050] A second aspect of the present invention provides a method for preparing the above-mentioned marine 6 series aluminum alloy profile, wherein the preparation method comprises:

[0051] The aluminum alloy raw materials are melted at a melting temperature of 760-780°C, and electromagnetic stirring is combined with mechanical stirring, refining, casting, online degassing, filtering, and homogenization are performed, wherein the casting speed is 50-80 mm / min;

[0052] The aluminum alloy ingot after homogenization treatment is extruded, the working band width of the extrusion die is 3-4mm, and the slope angle of the diversion pit is 12-18 degrees;

[0053] The extruded aluminum alloy material is cooled by water, and the distance between the quenching tank and the front wall of the extrusion device is less than 300mm;

[0054] The quenched aluminum alloy material is subjected to thermal insulation aging using a single-stage aging system.

[0055] In the present invention, the above-mentioned specific high-quality melting and casting, multi-stage homogenization control, rapid extrusion-online quenching preparation method is adopted to obtain a marine 6 series aluminum alloy profile having alloy strength, corrosion resistance, fatigue resistance and welding performance.

[0056] In the present invention, in order to match the high-temperature casting process, it is necessary to appropriately reduce the casting speed to ensure the quality of ingot molding. Reducing the casting speed can also effectively reduce the transition zone size during the ingot casting process, reduce the liquid cavity depth, reduce the brittle geometric area where thermal cracks are formed, and reduce the tendency of thermal cracking.

[0057] In the present invention, a high-temperature smelting process is adopted to ensure that the aluminum-erbium master alloy and the aluminum-zirconium master alloy are fully dissolved, and the aluminum-erbium and aluminum-zirconium master alloys are added at a temperature above 780°C. Due to the high alloying degree, the alloy is a high-component hard alloy, the metal fluidity is poor, and the deformation resistance is large. In order to improve the product formability and the surface quality of the profile, the structure of the extrusion die is optimized, and the width of the die working belt is reduced. After the width of the die working belt is reduced, the friction of the metal in the die is reduced, and the hard particles in the alloy are prevented from precipitating and adhering to the surface of the profile under high temperature conditions to produce a surface unevenness, thereby improving the surface quality of the product; because the alloy needs to be produced and prepared under a high-temperature, high-speed and high-pressure extrusion process, the aluminum alloy is prone to high-temperature aluminum adhesion with the die working belt. When the width of the working belt is reduced, the contact area between the metal and the mold is reduced accordingly, which effectively reduces the phenomenon of high-temperature aluminum sticking and further improves the surface quality of the profile. In order to more efficiently prepare high-component hard aluminum alloy products, the extrusion pressure in the preparation process should be reasonably controlled. Insufficient extrusion pressure can easily cause the metal to be unable to form, and excessive extrusion pressure will reduce the service life of the extruder and the mold. Therefore, the mold structure is optimized, and the slope angle of the guide pit is increased. While reducing the extrusion pressure, the flow of metal in the mold is more uniform, which is more conducive to the flow of metal into the working belt and reduces the degree of deformation of the metal in the mold, thereby achieving the purpose of improving product formability and increasing the service life of the mold.

[0058] In the present invention, due to the high quenching sensitivity of high alloy materials, under the premise of ensuring the dimensional accuracy of the product, the fastest cooling rate should be adopted during online extrusion production, that is, water cooling, so as to achieve higher mechanical properties. Therefore, the distance between the quenching tank and the front wall of the extruder should be less than 300 mm. If the distance is longer, the product will stay at room temperature for a longer time after extrusion molding, thereby reducing the quenching temperature and weakening the quenching effect. The vacancy concentration in the matrix and the supersaturation of the solid solution will decrease to varying degrees, affecting the effect of subsequent aging strengthening. Therefore, the above-mentioned distance between the quenching tank and the front wall of the extruder is adopted to reduce the residence time of the product at room temperature after extrusion molding.

[0059] Preferably, the casting speed is 50 mm / min, which is adjusted to 80 mm / min within 5 minutes.

[0060] In the present invention, at the beginning of casting, there is only one cooling brought by the crystallizer, the cooling intensity is reduced, and a casting speed of 50 mm / min is adopted; after the beginning of casting, the ingot is subjected to secondary water cooling directly acting on the surface of the ingot through the action of the ingot guide head. According to the balance relationship between melt cooling and temperature, the casting speed needs to be gradually increased to ensure the molding quality of the ingot. The casting speed is gradually increased to 80 mm / min within 5 minutes. At this time, the casting parameters are stable and the liquid level in the flow channel is maintained at the same level.

[0061] According to the present invention, the electromagnetic stirring conditions are: the electromagnetic stirring time is 30-40 minutes, and the interval time is 5-10 minutes.

[0062] According to the present invention, the conditions for mechanical stirring are: stirring times are 2-3 times, and mechanical stirring time is 20-30 minutes.

[0063] According to some preferred embodiments of the present invention, electromagnetic stirring is performed for 30 minutes with an interval of 10 minutes, and mechanical stirring is performed twice, with each mechanical stirring time being 10-15 minutes.

[0064] In the present invention, the stirring method of combining the above-mentioned specific electromagnetic stirring with mechanical stirring is adopted.

[0065] According to the present invention, the refining conditions include: temperature of 720-740°C, time of 10-20 min, standing temperature of 715-740°C, standing time of 20 min-30 min, and refining agent dosage of 1.0-1.5 kg / T.

[0066] According to the present invention, the casting temperature is 720-750°C.

[0067] In the present invention, since the alloying degree is relatively high, it is necessary to increase the casting temperature to improve the melt fluidity and avoid pores and slag inclusion defects caused by high melt viscosity. However, too high a temperature will not only reduce the as-cast performance, but also increase the safety risk of the casting process, so the above casting temperature is selected.

[0068] According to some preferred embodiments of the present invention, 99% pure argon gas and a particle refining agent are used for refining.

[0069] According to some preferred embodiments of the present invention, the melt is purified by online degassing and filtering, and the online degassing uses a double-rotor degassing box for degassing.

[0070] According to the present invention, after the online degassing, the hydrogen content of the melt is less than 0.13 ml / 100 g Al.

[0071] In the present invention, the above-mentioned online degassing method is adopted, and the degassing efficiency is ≥50%.

[0072] According to the present invention, the filtration is a two-stage filtration, wherein the baking time of the filter plate is greater than 1 hour.

[0073] In the present invention, a 30ppi+40ppi ceramic filter plate is used for double-stage filtration.

[0074] According to the present invention, the homogenization treatment is 395-405°C×6h+485-495°C×8h+550-560°C×20h, and air cooling.

[0075] In the present invention, in order to ensure that the Er and Zr elements in the alloy can fully play their role, the ingot needs to be heated to a temperature below the solid solution temperature and kept warm for a period of time. At this temperature, the Er and Zr elements hardly dissolve, thus promoting the precipitation of fine Al3Er and Al3Zr secondary phases; at the same time, under the action of the non-equilibrium crystallization of the alloy, the primary phase not only has Mg2Si, but also contains a certain Q phase (AlCuMg). According to the dissolution characteristics and rules of the second phase, the AlFeMnSi insoluble phase is guaranteed to evolve in shape during homogenization, so the above homogenization system is selected. The multi-stage homogenization treatment process solves the problems of complex ingot alloy elements, high alloying degree, cooling water quenching during the casting process, large internal stress, easy thermal cracking, and because the alloy contains fine crystal elements such as Mn and Zr, the melt viscosity is large, the fluidity is poor, which is not conducive to melt dehydrogenation and slag removal, and the tendency of looseness and slag inclusion is increased.

[0076] According to the present invention, the extrusion conditions include a die temperature of 485-510°C, a cast rod heating temperature of 530-550°C, an extrusion barrel temperature of 400-460°C, an extrusion product speed of 5-10 m / min, a stretching amount of 0.6-1%, a stretching amount of 0.6-1%, an extrusion ratio of 31-34, an circumscribed circle diameter of 58-62 mm, and a cross-sectional area of ​​3.5-3.8 cm 2 .

[0077] In the present invention, the heating temperature of the ingot is increased, thereby increasing the quenching temperature of the profile and improving the mechanical properties of the profile.

[0078] According to the present invention, the single-stage aging system is 170-175°C×8-12h.

[0079] According to the present invention, in the single-stage aging, the parking time is ≤2h.

[0080] A third aspect of the present invention provides a marine 6 series aluminum alloy profile produced by the above-mentioned preparation method.

[0081] Test Method

[0082] The composition test method of marine 6 series aluminum alloy profiles is in accordance with GB / T7999-2015 "Photoelectric Direct Reading Emission Spectroscopy Analysis Method for Aluminum and Aluminum Alloys", and the test equipment is ARL-3460 direct reading spectrometer.

[0083] The mechanical properties test method is in accordance with GB / T16865-2013 "Specimens and methods for tensile testing of deformed aluminum, magnesium and their alloy products", and the test equipment is AG-X 100KN electronic universal testing machine.

[0084] The high-magnification structure inspection standard is in accordance with GB / T6892-2015 "General Industrial Aluminum and Aluminum Alloy Extruded Profiles", the test method is GB / T3246.1-2012 "Deformed Aluminum and Aluminum Alloy Products Structure Inspection Method" Part 1: Microstructure Inspection Method, and the test equipment is AXIO universal research-grade inverted material microscope.

[0085] The macroscopic test standard is in accordance with GB / T6892-2015 "General Industrial Aluminum and Aluminum Alloy Extruded Profiles", and the test method is GB / T3246.1-2012 "Deformed Aluminum and Aluminum Alloy Products Microstructure Test Method" Part 2: Macroscopic Microstructure Test Method, and the test solution is alkaline corrosive solution.

[0086] The exfoliation corrosion performance test standard is in accordance with GB / T22639-2008 "Exfoliation Corrosion Test Method for Aluminum Alloy Processing Products", and the test equipment is a digital display constant temperature water bath crucible.

[0087] The fatigue strength performance test standard is in accordance with GB / T37616-2019 "Axial Force Controlled Fatigue Test Method for Aluminum Alloy Extrusion Profiles". The test equipment is Amsler 100HFP 5100 high frequency fatigue testing machine. The conditions are fatigue strength 200MPa, R=0.1, Kt=1, f=10-200Hz, loading waveform = sine wave, cycle 1.0×107 times.

[0088] The technical scheme of the present invention is further described in detail below in conjunction with the accompanying drawings and embodiments. Obviously, the embodiments described herein are only some embodiments of the present invention and are not intended to limit the present invention. Based on the embodiments of the present invention, all other embodiments implemented by ordinary technicians in this field without making creative improvements belong to the protection scope of the present invention.

[0089] Embodiment 1:

[0090] The melting temperature is 780℃, and electromagnetic stirring and mechanical stirring are used. The electromagnetic stirring is 30 minutes each time with an interval of 10 minutes; the mechanical stirring is twice, each time for 25 minutes. 99% pure argon gas plus granular refining agent is used for refining, the refining temperature is 732℃, the refining agent dosage is 1.5kg / T, and the refining time is 15 minutes; the static temperature is 725℃, and the time is 15 minutes; the melt is purified by online degassing and filtering. The online degassing uses a double rotor degassing box for degassing, and the degassing efficiency is ≥50%. The hydrogen content of the melt after treatment is <0.13ml / 100gAl; 30ppi+40ppi ceramic filter plates are used for online double-stage filtration, and the filter box is baked for more than 1h before use. Semi-continuous casting, casting temperature 750℃, casting speed 50mm / min, increased to 80mm / min within 5min, no waste is allowed to be added during the smelting process, the slag content of the ingot must meet the secondary requirements in GB / T32186-2015, and the low-multiple grain size must meet the secondary requirements in GB / T3246.2-2012. The homogenization treatment adopts a three-stage homogenization process: heating rate 25℃ / h, 400℃×6h+490℃×8h+555℃×20h, air cooling.

[0091] The extrusion was carried out using an 880T extruder, with a casting rod length of 400 mm, a casting rod heating temperature of 530 °C, a mold temperature of 490 °C, an extrusion barrel temperature of 430 °C, an extrusion product speed of 5 m / min, an extrusion die working band width of 3.3 mm, a guide pit slope angle of 15 degrees, an extrusion ratio of 33.3, an circumscribed circle diameter of 60 mm, and a cross-sectional area of ​​3.685 cm 2 , the aging system is: 175℃×8h.

[0092] After extrusion, water cooling is performed, and the distance between the quenching tank and the front wall of the extrusion device is less than 300mm. The extruded profile product is stretched and straightened, and the stretching amount is 0.7%; the profile product should be immediately aged after stretching, and the parking time is ≤2h. Marine 6 series aluminum alloy profile A1 is obtained.

[0093] The composition of the A1 alloy is shown in Table 1 below.

[0094] Example 2

[0095] The melting temperature is 780℃, and electromagnetic stirring and mechanical stirring are used. The electromagnetic stirring is 30 minutes each time with an interval of 10 minutes; the mechanical stirring is twice, each time for 25 minutes. 99% pure argon gas plus granular refining agent is used for refining, the refining temperature is 735℃, the refining agent dosage is 1.5kg / T, and the refining time is 15 minutes; the static temperature is 727℃, and the time is 30 minutes; the melt is purified by online degassing and filtering. The online degassing uses a double rotor degassing box for degassing, and the degassing efficiency is ≥50%. The hydrogen content of the melt after treatment is <0.13ml / 100gAl; 30ppi+40ppi ceramic filter plates are used for online double-stage filtration, and the filter box is baked for more than 1h before use. Semi-continuous casting, casting temperature 750℃, casting speed 50mm / min, increased to 80mm / min within 5min, no waste is allowed to be added during the smelting process, the slag content of the ingot must meet the secondary requirements in GB / T32186-2015, and the low-multiple grain size must meet the secondary requirements in GB / T3246.2-2012. The homogenization treatment adopts a three-stage homogenization process: heating rate 25℃ / h, 400℃×6h+490℃×8h+555℃×20h, air cooling.

[0096] The extrusion was carried out using an 880T extruder, with a casting car body, a length of 430 mm, a casting heating temperature of 520 °C, a die temperature of 490 °C, an extrusion barrel temperature of 430 °C, an extrusion product speed of 6 m / min, an extrusion die working band width of 3.5 mm, a guide pit slope angle of 17 degrees, an extrusion ratio of 33.3, an circumscribed circle diameter of 60 mm, and a cross-sectional area of ​​3.685 cm 2 , the aging system is: 175℃×8h.

[0097] After extrusion, water cooling is performed, and the distance between the quenching tank and the front wall of the extrusion device is less than 300mm. The extruded profile product is stretched and straightened, and the stretching amount is 0.9%; the profile product should be immediately aged after stretching, and the parking time is ≤2h. Marine 6 series aluminum alloy profile A2 is obtained.

[0098] The composition of A2 alloy is shown in Table 1 below.

[0099] Example 3

[0100] The melting temperature is 780℃, and electromagnetic stirring and mechanical stirring are used. The electromagnetic stirring is 30 minutes each time with an interval of 10 minutes; the mechanical stirring is twice, each time for 25 minutes. 99% pure argon gas plus granular refining agent is used for refining, the refining temperature is 730℃, the refining agent dosage is 1.5kg / T, and the refining time is 15 minutes; the static temperature is 725℃, and the time is 30 minutes; the melt is purified by online degassing and filtering. The online degassing uses a double rotor degassing box for degassing, and the degassing efficiency is ≥50%. The hydrogen content of the melt after treatment is <0.13ml / 100gAl; 30ppi+40ppi ceramic filter plates are used for online double-stage filtration, and the filter box is baked for more than 1h before use. Semi-continuous casting, casting temperature 730℃, casting speed 50mm / min, increased to 80mm / min within 5min, no waste is allowed to be added during the smelting process, the slag content of the ingot must meet the secondary requirements in GB / T32186-2015, and the low-multiple grain size must meet the secondary requirements in GB / T3246.2-2012. The homogenization treatment adopts a three-stage homogenization process: heating rate 25℃ / h, 400℃×6h+490℃×8h+555℃×20h, air cooling.

[0101] The extrusion was carried out using an 880T extruder, with a casting car body, a length of 430 mm, a casting heating temperature of 520 °C, a die temperature of 490 °C, an extrusion barrel temperature of 430 °C, an extrusion product speed of 8 m / min, an extrusion die working band width of 3.7 mm, a guide pit slope angle of 13 degrees, an extrusion ratio of 33.3, an circumscribed circle diameter of 60 mm, and a cross-sectional area of ​​3.685 cm 2 , the aging system is: 175℃×8h.

[0102] After extrusion, water cooling is performed, and the distance between the quenching tank and the front wall of the extrusion device is less than 300mm. The extruded profile product is stretched and straightened, and the stretching amount is 0.8%; the profile product should be immediately aged after stretching, and the parking time is ≤2h. Marine 6 series aluminum alloy profile A3 is obtained.

[0103] The composition of A3 alloy is shown in Table 1 below.

[0104] Comparative Example 1

[0105] A marine 6 series aluminum alloy profile was prepared in the same manner as in Example 1, except that the casting speed was 95 mm / min to obtain a marine 6 series aluminum alloy profile DA1.

[0106] The composition of DA1 alloy is shown in Table 1 below.

[0107] Comparative Example 2

[0108] A marine 6-series aluminum alloy profile was prepared in the same manner as in Example 1, except that the working band width of the extrusion die was 6 mm and the slope angle of the guide pit was 0 degrees, thereby obtaining a marine 6-series aluminum alloy profile DA2.

[0109] The composition of DA2 alloy is shown in Table 1 below.

[0110] Comparative Example 3

[0111] A marine 6 series aluminum alloy profile was prepared in the same manner as in Example 1, except that the distance between the quenching tank and the front wall of the extrusion device was 500 mm, thereby obtaining a marine 6 series aluminum alloy profile DA3.

[0112] The composition of DA3 alloy is shown in Table 1 below.

[0113] Comparative Example 4

[0114] A marine 6 series aluminum alloy profile was prepared in the same manner as in Example 1, except for the alloy composition, to obtain a marine 6 series aluminum alloy profile DA4.

[0115] The composition of DA4 alloy is shown in Table 1 below.

[0116] The mechanical strength performance test of A1-A3 and DA1-DA4 is shown in Table 2.

[0117] Table 1

[0118] Mg Si Cu Mn Fe Zr Er Impurities Al A1 1.10 1.43 0.22 0.57 0.17 0.11 0.12 0.05 margin A2 0.87 0.89 0.58 0.46 0.17 0.13 0.12 0.05 margin A3 0.92 0.87 0.30 0.50 0.16 0.15 0.12 0.05 margin DA1 1.10 1.43 0.22 0.57 0.17 0.11 0.12 0.05 margin DA2 1.10 1.43 0.22 0.57 0.17 0.11 0.12 0.05 margin DA3 1.10 1.43 0.22 0.57 0.17 0.11 0.12 0.05 margin DA4 0.80 0.85 0.15 0.10 0.2 0.01 0.01 0.05 margin

[0119] Table 2

[0120] Sample No. Elongation strength Rp0.2 / Mpa≥350 Tensile strength Rm / Mpa Elongation after fracture A50mm% in conclusion A1 1# 396 416 14.5 qualified 2# 390 414 14.5 qualified 3# 392 414 13.5 qualified A2 1# 360 397 15.4 qualified 2# 367 403 13.2 qualified 3# 368 404 14.3 qualified A3 1# 396 416 14.5 qualified 2# 390 414 14.5 qualified 3# 392 414 13.5 qualified DA1 1# 322 366 11 Failure 2# 330 373 11 Failure 3# 337 362 11.5 Failure DA2 1# 335 362 12 Failure 2# 340 369 11 Failure 3# 336 375 11 Failure DA3 1# 327 361 11.5 Failure 2# 329 359 11.5 Failure 3# 330 367 12 Failure DA4 1# 325 366 12 Failure 2# 321 362 12 Failure 3# 329 366 11.5 Failure

[0121] A1-A3 and DA1-DA4 were tested for high magnification structure. A1-A3 was not burned and had no inclusions, so it was qualified. DA1-DA4 had inclusion defects in its structure and was unqualified.

[0122] A1-A3 and DA1-DA4 were tested at low magnification. A1-A3 had no defects such as cracks and shrinkage tails, and were qualified. DA1-DA4 had shrinkage tail layering defects and were unqualified.

[0123] A1-A3 and DA1-DA4 were tested for exfoliation corrosion performance. A1-A3 was PC grade and the results met the EA grade requirements and were qualified. The results of DA1-DA4 were EC grade and were unqualified.

[0124] A1-A3 and DA1-DA4 were tested for fatigue strength performance. A1-A3 did not break, but DA1-DA4 broke.

[0125] By comparing the embodiments with the comparative examples, it can be seen that the marine 6 series aluminum alloy profile provided by the present invention not only greatly improves the mechanical properties, but also improves the exfoliation corrosion resistance to PC-PA level by adjusting the melting and casting process, extrusion process and aging system, thus meeting the demand for high-strength and corrosion-resistant aluminum alloys for boat cabins.

[0126] The above description is only a preferred specific implementation manner of the present invention, but the protection scope of the present invention is not limited thereto. Any technician familiar with the technical field can make equivalent replacements or changes according to the technical solutions and inventive concepts of the present invention within the technical scope disclosed by the present invention, which should be covered by the protection scope of the present invention.

Claims

1. A 6 series aluminum alloy profile for shipbuilding, characterized in that: The components and their weight percentages in the aluminum alloy profile are: Si content is 0.9-1.5%; Fe content ≤ 0.2%; Cu content is 0.2-0.9%; Mn content is 0.2-0.8%; Mg content is 0.9-1.3%; Zn content is 0.02-0.5%; Er content is 0.02-0.2%; Zr content is 0.02-0.2%; The total content of other impurity elements is ≤0.15%; The balance is Al; The method for preparing the marine 6 series aluminum alloy profile comprises: The aluminum alloy raw materials are melted at a melting temperature of 760-780°C, and electromagnetic stirring is combined with mechanical stirring, refining, casting, online degassing, filtering, and homogenization are performed; The aluminum alloy ingot after homogenization treatment is extruded, the working band width of the extrusion die is 3-4mm, and the slope angle of the diversion pit is 12-18 degrees; The extruded aluminum alloy material is cooled by water, and the distance between the quenching tank and the front wall of the extrusion device is less than 300mm; The aluminum alloy material after quenching is subjected to thermal insulation aging, and a single-stage aging system is adopted; The casting speed was 50 mm / min at the beginning of casting and adjusted to 80 mm / min within 5 min. The casting temperature was 730-750°C. Wherein, the homogenization treatment is 395-405℃×6h+485-495℃×8h+550-560℃×20h, and air cooling.

2. A method for preparing the marine 6 series aluminum alloy profile according to claim 1, characterized in that: The preparation method comprises: The aluminum alloy raw materials are melted at a melting temperature of 760-780°C, and electromagnetic stirring is combined with mechanical stirring, refining, casting, online degassing, filtering, and homogenization are performed; The aluminum alloy ingot after homogenization treatment is extruded, the working band width of the extrusion die is 3-4mm, and the slope angle of the guide pit is 12-18 degrees; The extruded aluminum alloy material is cooled by water, and the distance between the quenching tank and the front wall of the extrusion device is less than 300mm; The aluminum alloy material after quenching is subjected to thermal insulation aging, and a single-stage aging system is adopted; The casting speed was 50 mm / min at the beginning of casting and adjusted to 80 mm / min within 5 min. The casting temperature was 730-750°C. Wherein, the homogenization treatment is 395-405℃×6h+485-495℃×8h+550-560℃×20h, and air cooling.

3. The preparation method according to claim 2, characterized in that: The electromagnetic stirring conditions are: the electromagnetic stirring time is 30-40 minutes, and the interval time is 5-10 minutes; The mechanical stirring conditions are: stirring times are 2-3 times, and the mechanical stirring time is 20-30 minutes; The refining conditions include: temperature of 720-740°C, time of 10-20min, standing temperature of 715-740°C, standing time of 20min-30min, and refining agent dosage of 1.0-1.5kg / T; After the online degassing, the hydrogen content of the melt is less than 0.13 ml / 100 g Al.

4. The preparation method according to claim 2, characterized in that: The filtration is a two-stage filtration, wherein the filter plate baking time is greater than 1 hour.

5. The preparation method according to claim 2, characterized in that: The extrusion conditions include a die temperature of 485-510°C, a cast rod heating temperature of 520-550°C, an extrusion barrel temperature of 400-460°C, an extrusion product speed of 5-10 m / min, a stretching amount of 0.6-1%, an extrusion ratio of 31-34, an circumscribed circle diameter of 58-62 mm, and a cross-sectional area of ​​3.5-3.8 cm 2 .

6. The preparation method according to claim 2, characterized in that: The single-stage aging system is 170-175°C×8-12h.

7. A marine 6 series aluminum alloy profile obtained by the preparation method according to any one of claims 2 to 6.

Images