5-series aluminum alloy profile for ships and preparation method of 5-series aluminum alloy profile

Abstract

The invention relates to the field of aluminum alloy for ships, in particular to a 5-series aluminum alloy profile for ships and a preparation method of the 5-series aluminum alloy profile for ships. The Fe content is less than or equal to 0.15%; the content of Cu is less than or equal to 0.10%; the content of Mn is 0.6 to 0.8 percent; the content of Mg is 4.7 to 4.9 percent; the content of Cr is 0.05 to 0.25 percent; the Zn content is less than or equal to 0.20%; the content of Ti is less than or equal to 0.15%; the content of B is 0.0005 to 0.003 percent; the single content of other impurity elements is less than or equal to 0.05%; the aluminum alloy profile has excellent mechanical properties, low metal flow difference, stable performance uniformity and excellent strong plasticity and corrosion resistance, the longitudinal bending degree is smaller than or equal to 1.5 mm / m, and the longitudinal torsion degree is smaller than or equal to 1.0 mm / m.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of aluminum alloy for ships, in particular to a 5-series aluminum alloy profile for ships and a preparation method thereof. BACKGROUND

[0002] 5083 aluminum alloy takes Mg as the main additive element, and the magnesium content is controlled in the interval of 4.0-4.9%, which not only has excellent forming performance, but also has outstanding performance in resisting atmospheric corrosion and seawater corrosion, and various deformation processing performance is also very good. It is worth noting that it can still maintain good mechanical properties in low temperature environment, which makes it show unique advantages in ship body manufacturing. Compared with traditional steel materials, 5083 aluminum alloy can significantly reduce the weight of the ship body, thereby realizing the improvement of transportation efficiency and the reduction of energy consumption cost.

[0003] Compared with conventional profiles, the 5083 aluminum alloy profile for ships has higher rigidity and strength, excellent buckling resistance, and the material distribution is more reasonable, and the weight reduction effect is significant. However, in the extrusion process, the large width-thickness ratio characteristics of the 5083 aluminum alloy profile for ships also bring a series of technical difficulties, such as increased extrusion difficulty, significant metal flow difference, difficult performance uniformity control, and difficult size precision and flatness guarantee. At present, the preparation research on the 5083 aluminum alloy profile for ships with large width-thickness ratio is relatively less.

[0004] Therefore, it is urgent to provide a 5-series aluminum alloy profile for ships with excellent mechanical properties, low metal flow difference, stable performance uniformity, excellent strength plasticity and corrosion resistance, longitudinal bending degree ≤1.5mm / m, and longitudinal twisting degree ≤1.0mm / m, and a preparation method thereof. SUMMARY

[0005] The present application aims to solve the technical problem of how to provide a 5-series aluminum alloy profile for ships with excellent mechanical properties, low metal flow difference, stable performance uniformity, excellent strength plasticity and corrosion resistance, longitudinal bending degree ≤1.5mm / m, and longitudinal twisting degree ≤1.0mm / m, and a preparation method thereof.

[0006] In order to achieve the above-mentioned purpose, the present application provides a 5-series aluminum alloy profile for ships, wherein the components and their weight percentages in the profile are as follows: Si content ≤0.18 %; Fe content ≤0.15 %; Cu content ≤0.10 %; Mn content 0.6-0.8 %; Mg content 4.7-4.9 %; Cr content 0.05-0.25 %; Zn content ≤0.20 %; Ti content ≤0.15 %; B content is 0.0005-0.003 %; Other impurity elements single content ≤0.05 %; Other impurity elements total content ≤0.15 %; The balance is Al.

[0007] The second aspect of the application provides a preparation method of the 5 series aluminum alloy profile for ship in claim 1, wherein the method comprises: Melting, homogenization treatment, extrusion, annealing; The thickness L1 of the end working zone of the extrusion die is (0.4-0.5) x profile wall thickness, unit: mm, and the thickness L2 of the middle working zone of the extrusion die is profile wall thickness ± 2, unit: mm.

[0008] The beneficial effects of the application are: (1) The application optimizes Mg, Mn elements in 5083 aluminum alloy, reduces Fe and Si content, reduces the existence of brittle phases (such as Al6FeSi, Al4FeSi2, etc.) in the alloy, improves the strength and corrosion resistance of the alloy. Add B element, make it as a nucleation core to refine the ingot grain, improve the flowability of hot extrusion, reduce the surface defects (such as coarse grain ring, crack) of wide profile, and further improve the performance uniformity through fine grain strengthening. At the same time, the two-stage annealing process is adopted to make the second phase in the aluminum alloy matrix more dispersed and uniform. Finally, through the joint action of composition optimization and two-stage annealing system, the 5083 aluminum alloy profile for ship is obtained, the yield strength is up to 162 MPa, the tensile strength is up to 330 MPa, the maximum strength difference in thickness direction is less than 5 MPa, the welding coefficient is up to 0.9 or more, and the exfoliation corrosion reaches PA level.

[0009] (2) According to the product size, the thickness of the working zone at different positions of the die is reasonably matched, and the convergence angle of the flow guide die is accurately controlled, so as to effectively control the metal flow rate, so that the longitudinal bending degree of the 5083 aluminum alloy profile for ship is ≤1.5 mm / m, and the longitudinal twisting degree is ≤1.0 mm / m. BRIEF DESCRIPTION OF DRAWINGS

[0010] Figure 1 It is a schematic diagram of the working zone at the section of different aluminum alloy profiles.

[0011] Figure 2 It is the exfoliation corrosion diagram of example 3.

[0012] Figure 3 It is the exfoliation corrosion diagram of comparative example 1.

[0013] Figure 4Bend detection chart for Example 1.

[0014] Figure 5 Bend detection chart for Comparative Example 4. DETAILED DESCRIPTION

[0015] The endpoints of the ranges and any values disclosed herein are not limited to the precise values recited as the exact dimensions are not considered critical for the purposes of the application. The ranges disclosed herein are understood to include all values and subranges therebetween unless otherwise indicated. For values which are expressed as ranges, any intervening values, and any subranges thereof, are understood to be disclosedin this application unless otherwise indicated.

[0016] In the prior art, it is difficult to prepare a 5-series aluminum alloy profile with excellent mechanical properties, low metal flow difference, stable performance uniformity, excellent strength and plasticity and corrosion resistance, longitudinal bending ≤1.5 mm / m, and longitudinal twisting ≤1.0 mm / m, with the existing alloy composition and preparation process.

[0017] In the present application, the inventors have found that, by controlling the alloy composition and adjusting the processing technology, the performance of the 5-series aluminum alloy profile can meet the requirements, with excellent mechanical properties, low metal flow difference, stable performance uniformity, excellent strength and plasticity and corrosion resistance, longitudinal bending ≤1.5 mm / m, and longitudinal twisting ≤1.0 mm / m.

[0018] To achieve this goal, the inventors have found that the above-mentioned purpose can be achieved by using a specific composition of each component and an extrusion die, and further, a specific annealing process makes the performance of the aluminum alloy profile more excellent.

[0019] The present application provides a 5-series aluminum alloy profile for ships, wherein the components and their weight percentages in the profile are as follows: Si content ≤0.18 %; Fe content ≤0.15 %; Cu content ≤0.10 %; Mn content 0.6-0.8 %; Mg content 4.7-4.9 %; Cr content 0.05-0.25 %; Zn content ≤0.20 %; Ti content ≤0.15 %; B content 0.0005-0.003 %; Other impurity elements ≤0.05 % individually; Other impurity elements ≤0.15 % in total; Balance Al.

[0020] In the present application, the Mg and Mn element composition is optimized, compared with the conventional 5083 aluminum alloy, the Mg content is controlled to be at the upper limit of the composition interval, the solid solution strengthening effect can be maximized, and the alloy strength can be directly improved, when the Mg content exceeds 4.9%, the Mg element segregation at the grain boundary will be intensified, and a corrosion-prone area will be formed, and the corrosion resistance will be reduced; further control the Mn element to be at the upper limit of the composition interval, the Mg element segregation on the grain boundary can be inhibited, and enough Al6Mn dispersed phase with a potential close to that of the Al matrix can be promoted to reduce the corrosion driving force, both the dispersion strengthening, grain refinement effect and the corrosion resistance can be ensured, and the coarse Al6Mn phase caused by excessive Mn can be avoided, which becomes a stress concentration point and reduces the plasticity; The Fe and Si contents are reduced to the contents defined in the present application, the brittle phase (such as Al6FeSi, Al4FeSi2, etc.) in the alloy is reduced, so that the strengthening effect of Mg and Mn can be more fully played (avoiding the consumption of Mg by Mg2Si and the consumption of Mn by Al6(Fe, Mn)), so that the strength and plasticity can be improved, the difference between the electrode potential of the brittle phase Al6FeSi, Al4FeSi2 and the Al matrix is large, and the reduction of the amount can effectively reduce the corrosion driving force and improve the corrosion resistance, in addition, the hardness of the brittle phase Al6FeSi, Al4FeSi2 is high, and the friction with the die is intensified, which can cause the extrusion resistance to rise, and the reduction of Fe and Si can reduce the brittle phase and improve the extrudability.

[0021] The addition of B element can effectively refine the ingot grain, at this time the grain deformation resistance is lower, the grain boundary sliding is more coordinated, and the extrudability is improved. In the fine-grained structure, the grain boundary area increases significantly, the segregation degree of Mg and other elements is reduced, the potential difference between the grain boundary and the matrix can be reduced, and the corrosion can be inhibited.

[0022] Through the strengthening of Mg and Mn and the organization regulation, the strength and corrosion resistance are laid, the reduction of Fe and Si eliminates the deterioration of the performance of the brittle phase, the addition of B element refines the grain and strengthens the synergistic effect, and finally the strength and plasticity of the 5083 alloy, the corrosion resistance and the extrudability are improved.

[0023] The second aspect of the present application provides a preparation method of the 5-series aluminum alloy profile for ships in claim 1, wherein the method comprises: melting and casting, homogenization treatment, extrusion, and annealing; The thickness L1 of the end working zone of the extrusion die is (0.4-0.5) x profile wall thickness, and the unit is mm, and the thickness L2 of the middle working zone of the extrusion die is profile wall thickness ± 2, and the unit is mm.

[0024] In the present application, the drawings attached to the specification Figure 1It can be known that the end working zone is the working zone corresponding to the die at both ends of the profile, and the middle working zone is the working zone corresponding to the die in the middle of the profile, wherein the end working zone is one sixteenth of the total length of the profile, and the middle working zone is seven eighths of the total length of the profile, the profile provided by the application has high Mg and Mn alloy elements, and too short working zone will cause uneven flow rate, so that the profile is distorted or has size deviation, too long working zone will cause heat due to friction, so that the local temperature is too high, which causes the grain of the 5083 aluminum alloy to be coarse, the mechanical property is reduced, and even the surface appears to be'stuck' and pulled. Especially, the end working zone is the key to control the edge size, shape stability and reduce edge defects of the profile, and the middle working zone directly determines the thickness of the middle region of the profile, if the middle working zone is unevenly designed, the profile will have thickness fluctuation, and then affect the flatness, and the end working zone and the middle working zone cooperatively solve the problems of 'bending, uneven thickness and edge defects' in the profile extrusion.

[0025] For the alloy composition provided by the application, the Fe and Si are effectively reduced to reduce brittle phase, the B element is added to refine the ingot grain, so that the grain deformation resistance is lower, the grain boundary sliding is more coordinated, the homogenization treatment is matched, the working zone thickness at different positions of the die is reasonably matched according to the product size, and the extrudability of the alloy is effectively improved.

[0026] According to the application, the cross section of the die is a first die cross section, a second die cross section, a third die cross section and a fourth die cross section. According to the cross section 1 in the description of the application, Figure 1 The first die cross section is a rectangle, and in the length direction, one sixteenth of the total length of the profile cross section at both ends is an end working zone, and the remaining part is a middle working zone. According to the cross section 2 in the description of the application, Figure 1 The second die cross section is a figure formed by two rectangles vertically contacting, the middle line of the length of the first rectangle coincides with the middle line of the width of the second rectangle, one sixteenth of the total length of the first rectangle at both ends is an end working zone, and the remaining part of the first rectangle is a middle working zone, one sixteenth of the total length of the right end of the second rectangle is an end working zone, and the remaining part of the second rectangle is a middle working zone. According to the cross section 3 in the description of the application, Figure 1the third die section is composed of a third rectangle, a fourth rectangle and a fifth rectangle, the third rectangle and the fifth rectangle are parallel, the fourth rectangle is in contact with the third rectangle perpendicularly, the fourth rectangle is in contact with the fifth rectangle perpendicularly, the middle line of the length of the third rectangle coincides with the middle line of the width of the fourth rectangle, the middle line of the length of the fifth rectangle coincides with the middle line of the width of the fourth rectangle, the length and the width of the third rectangle are the same as the length and the width of the fifth rectangle, one-sixteenth of the total length of the left and right ends of the third rectangle is the end working zone, the rest of the third rectangle is the middle working zone, one-sixteenth of the total length of the left and right ends of the fifth rectangle is the end working zone, the rest of the fifth rectangle is the middle working zone, the fourth rectangle is the middle working zone; According to the specification of the present application Figure 1 the fourth die section is composed of a sixth rectangle, a seventh rectangle and an eighth rectangle, the sixth rectangle and the seventh rectangle are in contact perpendicularly, the eighth rectangle and the seventh rectangle are in contact perpendicularly, the middle line of the width of the sixth rectangle and the length of the similar one end of the seventh rectangle are equal to the length of the sixth rectangle, the middle line of the width of the eighth rectangle and the length of the similar one end of the seventh rectangle are equal to the length of the eighth rectangle, the length and the width of the sixth rectangle are the same as the length and the width of the eighth rectangle, the length of the sixth rectangle is greater than one-sixteenth of the length of the seventh rectangle, one-sixteenth of the total length of the left and right ends of the seventh rectangle is the end working zone, the rest of the seventh rectangle is the middle working zone, one-sixteenth of the total length of the one end of the sixth rectangle away from the seventh rectangle is the end working zone, the rest of the sixth rectangle is the middle working zone, one-sixteenth of the total length of the one end of the eighth rectangle away from the seventh rectangle is the end working zone, the rest of the eighth rectangle is the middle working zone.

[0027] According to the present application, the convergence angle of the flow guide die of the extrusion die is 45°-60°.

[0028] In the application, the Mg and Mn alloy elements in the profile provided by the application are very high, if the flow guide die is not reasonably designed, it may cause insufficient metal supply in some parts, resulting in incomplete filling, or uneven flow causing internal stress, and the profile is deformed after extrusion. The convergence angle of the conventional 5083 alloy flow guide die is usually 30°-90°, when the convergence angle is 30°-60°, the metal flow path is long, the deformation process is more gentle, and the metal in each region is more uniform and the stress distribution is more uniform. For the alloy provided by the application, containing 0.6-0.8% Mn, Al6Mn dispersed phase is formed, small angle convergence can make the grain breakage more uniform during the deformation process, avoiding "abnormal grain refinement" or "coarsening" caused by excessive local strain, such as excessive strain at the edge causing too fine grain, insufficient strain in the middle causing coarse grain, thereby improving the uniformity of the mechanical properties of the plate. If the convergence angle is 60°-90°, the metal flow path is short, the deformation is more "violent", and vortex or local turbulence is easily formed at the outlet of the flow guide cavity. For high Mg alloy, large angle may cause micro-cracks in the local metal due to "shear deformation concentration", especially at the edge of the profile. The size of the convergence angle will affect the extrudability of the metal, that is, the deformation resistance of the metal, when the convergence angle is small, the contact area of the metal with the flow guide die is large and the friction path is long, the deformation resistance of the aluminum alloy is low, when the convergence angle is large, the contact area is small and the friction is large, the deformation resistance of the metal is high. The specific convergence angle of the flow guide die is matched with the alloy composition, homogenization treatment and reasonable matching of the die thickness at different positions according to the product size, which can significantly improve the size accuracy, performance uniformity and corrosion resistance of the profile.

[0029] According to the application, the extrusion conditions include that the die heating temperature is 450-480℃, the cast bar after homogenization treatment is heated to 420-460℃, the extrusion ratio is 20-35, the extrusion speed is 0.5-1.5 m / min, the quenching mode is water mist, then online stretching straightening is carried out, the stretching amount is 0.5-1.5%, the thickness of the extruded profile is 10-30 mm, and the maximum width is 100-600 mm.

[0030] In the application, the extrusion speed is controlled, too fast extrusion speed will cause uneven metal flow, and the process of filling the die cavity with metal will be out of control, resulting in profile size out of tolerance; when the extrusion speed is too low, the contact time of the die and the metal is prolonged, which may cause the metal to stick to the die due to too low local temperature, resulting in "die sticking" phenomenon, affecting the surface finish of the profile.

[0031] According to the application, the conditions of the melting and casting include: preheating the aluminum ingot and the intermediate alloy at 100-200 DEG C, placing the aluminum ingot in a melting furnace, heating to 800-850 DEG C, after the aluminum ingot is melted, reducing the temperature to 730-760 DEG C, then filling in the Al-Fe, Al-Si, Al-Mn, Al-Cr, Al-B intermediate alloy, after all are melted, performing electromagnetic stirring, the stirring time is 30-60 min, then adding the magnesium ingot, standing for 10-14 min, using the powder spraying method to perform degassing refining on the melt, removing the surface dross through mechanical slagging, standing for 20-25 min, when the melt temperature is reduced to 715-730 DEG C, performing semi-continuous casting, during the casting, adding the Al-Ti-B wire to refine the alloy.

[0032] According to the application, the conditions of the homogenization treatment include: treating at 520-540 DEG C for 14-16 h, using water mist cooling, the cooling rate is 15-20 DEG C / min, cooling to 20-30 DEG C.

[0033] According to the application, the conditions of the annealing include: performing two-stage annealing treatment on the profile, the first-stage annealing heating system is from 20-25 DEG C to 310-330 DEG C, the first-stage annealing heating rate is 70-90 DEG C / h, the first-stage annealing holding system is holding at 310-330 DEG C for 1-1.5 h, the second-stage annealing heating system is from 310-330 DEG C to 340-360 DEG C, the second-stage annealing heating rate is 40-60 DEG C / h, the second-stage annealing holding system is holding at 340-360 DEG C for 0.5-1 h, air cooling to 20-30 DEG C, obtaining the 5-series aluminum alloy profile for ships.

[0034] In the present application, the Mg content is relatively high. If single-stage annealing is adopted, continuous grain boundary precipitates (such as β phase) are easily formed, resulting in intergranular corrosion. In addition, the single-stage annealing process causes uneven internal stress elimination in the material, resulting in a large difference in strength in the thickness direction, serious deformation after welding. After specific two-stage annealing treatment, the first-stage annealing is heated to 310-330℃. The temperature is relatively low, and the heating rate is controlled at 70-90℃ / h. In this stage, part of the magnesium atoms will begin to diffuse and nucleate at the grain boundaries and precipitate β phase. However, due to the relatively low temperature and suitable heating rate, the growth rate of β phase is controlled, and it will not quickly connect to form a continuous phase, but lay the foundation for subsequent precipitation, so that a certain number of initial β phase particles are formed at the grain boundaries. Subsequently, the second-stage annealing is heated from 310-330℃ to 340-360℃, and the heating rate is reduced to 40-60℃ / h. In this stage, the temperature is slightly higher, which promotes the further diffusion of magnesium atoms, but the lower heating rate makes the diffusion process more stable. At this time, the magnesium atoms at the grain boundaries can be more uniformly distributed, and continue to precipitate around the initial β phase particles formed in the first-stage annealing, so that the β phase exists in the form of discontinuous fine particles, thereby cutting off the possible corrosion channel and significantly improving the intergranular corrosion resistance and stress corrosion cracking (SCC) resistance. In addition, the two-stage annealing uniformly eliminates the internal stress in the alloy by reasonably controlling the heating rate. The heating rate and holding time of the first-stage annealing allow the material to release internal stress at a lower temperature to a certain extent, so that the internal stress of the material is preliminarily relieved. After entering the second-stage annealing, the slower heating rate and suitable holding temperature allow different positions in the material to further uniformly release internal stress as the temperature rises steadily. This step-by-step release of internal stress avoids uneven internal stress elimination caused by rapid temperature changes in single-stage annealing, thereby improving the dimensional stability and strength uniformity of the material and reducing the risk of deformation after processing and welding.

[0035] Test method The composition test method of the aluminum alloy profile is in accordance with GB / T7999-2015 Aluminum and Aluminum Alloy Optical Direct-Reading Emission Spectrometric Analysis Method, and the test equipment is ARL-3460 direct-reading spectrometer.

[0036] Tensile strength (R m ) Test standard is GB / T 228.1-2021.

[0037] Yield strength (Rp0.2) Test standard is GB / T 228.1-2021.

[0038] Breaking elongation (A50) Test standard is GB / T 228.1-2021.

[0039] Room temperature tensile mechanical properties test: carried out in accordance with the relevant provisions of GB / T 228.1-2021 "Tensile tests on metallic materials - Part 1: Room temperature test methods", and the testing equipment is AG-X 100kN electronic universal testing machine.

[0040] Welding coefficient test: Conducted in accordance with the relevant provisions of GB / T 13816-2023 "Aluminum and aluminum alloy welding procedure qualification", welding equipment is Fronius TPS5000, and welding method is MIG method.

[0041] Exfoliation corrosion test: carried out in accordance with the relevant provisions of GB / T 22639-2022 "Exfoliation corrosion test method for aluminum alloy products".

[0042] The technical solution of the present invention is further described in detail below with reference to 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 those of ordinary skill in the art without making creative improvements are within the scope of protection of the present invention.

[0043] Example 1 The chemical composition of the alloy is Si: 0.18%, Fe: 0.15%, Cu: 0.10%, Mn: 0.7%, Mg: 4.8%, Cr: 0.15%, Zn: 0.03%, Ti content is 0.03%, B content is 0.002%, the individual content of other impurity elements is ≤0.05%, the total content of other impurity elements is ≤0.15%, and the balance is Al.

[0044] Melting and casting: Preheat the aluminum ingot and master alloy at 150°C, place the aluminum ingot in a melting furnace, and heat it to 825°C. After the aluminum ingot is melted, reduce the temperature to 745°C, and then fill in Al-Fe, Al-Si, Al-Mn, Al-Cr, and Al-B master alloys. After all are melted, perform electromagnetic stirring for 45 minutes. Then add the magnesium ingot and let it stand for 12 minutes. Degas and refine the melt by powder spraying, remove the surface slag by mechanical skimming, and let it stand for 23 minutes. Semi-continuous casting is carried out when the melt temperature drops to 715-730°C. During the casting process, Al-Ti-B wire is added to refine the alloy.

[0045] Homogenization treatment: 530°C for 15 h, water mist cooling at a cooling rate of 18°C / min, cooling to 25°C.

[0046] extrusion: The thickness of the extruded profile is 30 mm, the cross section of the die is the first die cross section, the thickness of the end working zone is 0.5*30=15 mm, the thickness of the middle working zone is 30+2=32 mm, and the entrance section of the die is designed with a convergence angle of 50°.

[0047] The heating temperature of the die is 470 ℃, the cast bar after homogenization treatment is heated to 440 ℃, then extrusion is performed, the extrusion ratio is 35, the extrusion speed is 1.0 m / min, the quenching mode is water mist, then online stretching and straightening are performed, the stretching amount is 1.0%, the thickness of the extruded profile is 30 mm, the maximum width is 600 mm, and the 5-series aluminum alloy profile is obtained.

[0048] Annealing: the 5-series aluminum alloy profile is subjected to two-stage annealing treatment, the first-stage annealing temperature rising system is rising from 20 ℃ to 320 ℃, the first-stage annealing temperature rising rate is 80 ℃ / h, the first-stage annealing temperature holding system is holding at 320 ℃ for 1.2 h, the second-stage annealing temperature rising system is rising from 320 ℃ to 350 ℃, the second-stage annealing temperature rising rate is 50 ℃ / h, and the second-stage annealing temperature holding system is holding at 350 ℃ for 0.8 h. Then air cooling to 25 ℃, the 5-series aluminum alloy profile A1 for ships is obtained.

[0049] Example 2 The 5-series aluminum alloy profile for ships is prepared according to the preparation method of Example 1, except that the chemical composition of the alloy is selected as Mn: 0.8%, Mg: 4.9%, and the content of B is 0.003%.

[0050] Homogenization treatment: the temperature is 540 ℃ for 14 h.

[0051] The entrance section of the die is designed with a convergence angle of 45°.

[0052] The heating temperature of the die is 450 ℃, the cast bar after homogenization treatment is heated to 460 ℃, then extrusion is performed, and the extrusion speed is 0.5 m / min.

[0053] Annealing treatment: the 5083 aluminum alloy profile is subjected to two-stage annealing treatment, the first-stage annealing temperature rising system is rising from 20 ℃ to 330 ℃, the first-stage annealing temperature rising rate is 90 ℃ / h, the first-stage annealing temperature holding system is holding at 330 ℃ for 1 h, the second-stage annealing temperature rising system is rising from 330 ℃ to 360 ℃, the second-stage annealing temperature rising rate is 60 ℃ / h, and the second-stage annealing temperature holding system is holding at 360 ℃ for 0.5 h. Then air cooling to 25 ℃, the 5-series aluminum alloy profile A2 for ships is obtained.

[0054] Example 3 The 5-series aluminum alloy profile for ships is prepared according to the preparation method of Example 1, except that the chemical composition of the alloy is selected as Mn: 0.6%, Mg: 4.7%, and the content of B is 0.0005%.

[0055] Homogenization treatment: temperature 520℃ for 16h.

[0056] The die inlet section is designed with a 45° convergence angle.

[0057] The die heating temperature is 460℃, the cast bar after homogenization treatment is heated to 420℃, and then extrusion is performed at an extrusion speed of 1.5m / min.

[0058] Annealing treatment: the 5083 aluminum alloy profile is subjected to two-stage annealing treatment, the first-stage annealing temperature is increased to 310℃ at a rate of 70℃ / h, the first-stage annealing holding temperature is 310℃ for 1.5h, the second-stage annealing temperature is increased to 340℃ at a rate of 40℃ / h, the second-stage annealing holding temperature is 340℃ for 1h. Then air cooling to 25℃, obtaining the 5 series aluminum alloy profile A3 for ships.

[0059] Example 4 The 5 series aluminum alloy profile for ships is prepared according to the preparation method of Example 1, except that the alloy is selected with the chemical composition of Mn: 0.8%, Mg: 4.9%, and B content of 0.003%.

[0060] Homogenization treatment: temperature 540℃ for 14h.

[0061] The extruded profile thickness is 20mm, the die cross section is the first die cross section, the end working belt thickness L1 is 0.45x20=9mm, the middle working belt thickness L2 is 20-2=18mm, and the die inlet section is designed with a 55° convergence angle.

[0062] The die heating temperature is 450℃, the cast bar after homogenization treatment is heated to 460℃, and then extrusion is performed at an extrusion speed of 0.5m / min.

[0063] Annealing treatment: the 5083 aluminum alloy profile is subjected to two-stage annealing treatment, the first-stage annealing temperature is increased to 330℃ at a rate of 90℃ / h, the first-stage annealing holding temperature is 330℃ for 1h, the second-stage annealing temperature is increased to 360℃ at a rate of 60℃ / h, the second-stage annealing holding temperature is 360℃ for 0.5h. Then air cooling to 25℃, obtaining the 5 series aluminum alloy profile A4 for ships.

[0064] Example 5 The 5 series aluminum alloy profile for ships is prepared according to the preparation method of Example 1, except that the alloy is selected with the chemical composition of Mn: 0.8%, Mg: 4.9%, and B content of 0.003%.

[0065] Homogenization treatment: temperature 540℃ for 14h.

[0066] The extrusion profile thickness is 10 mm, the cross section of the die is the first die cross section, the end working zone thickness L1 is 0.4*10=4 mm, the middle working zone thickness L2 is 10-2=8 mm, and the die inlet section is designed with a 60° convergence angle.

[0067] The die heating temperature is 450℃, the cast bar after homogenization treatment is heated to 460℃, and then extrusion is performed at an extrusion speed of 0.5 m / min.

[0068] Annealing treatment: the 5083 aluminum alloy profile is subjected to two-stage annealing treatment, the first-stage annealing heating schedule is 20℃ to 330℃, the first-stage annealing heating rate is 90℃ / h, the first-stage annealing holding schedule is 1 h at 330℃, the second-stage annealing heating schedule is from 330℃ to 360℃, the second-stage annealing heating rate is 60℃ / h, and the second-stage annealing holding schedule is 0.5 h at 360℃. Then air cooling to 25℃, to obtain the 5-series aluminum alloy profile A5 for ships.

[0069] Example 6 The 5-series aluminum alloy profile for ships is prepared according to the preparation method of Example 1, except that the extrusion profile thickness is 20 mm, the cross section of the die is the second die cross section, the end working zone thickness L1 is 0.45*20=9 mm, and the middle working zone thickness L2 is 20-2=18 mm.

[0070] The 5-series aluminum alloy profile A6 for ships is obtained.

[0071] Example 7 The 5-series aluminum alloy profile for ships is prepared according to the preparation method of Example 1, except that the extrusion profile thickness is 16 mm, the cross section of the die is the third die cross section, the end working zone thickness L1 is 0.4*16=6.4 mm, and the middle working zone thickness L2 is 16-2=14 mm.

[0072] The 5-series aluminum alloy profile A7 for ships is obtained.

[0073] Example 8 The 5-series aluminum alloy profile for ships is prepared according to the preparation method of Example 1, except that the extrusion profile thickness is 10 mm, the cross section of the die is the fourth die cross section, the end working zone thickness L1 is 0.4*10=4 mm, and the middle working zone thickness L2 is 10-2=8 mm.

[0074] The 5-series aluminum alloy profile A8 for ships is obtained.

[0075] Comparative Example 1 The 5-series aluminum alloy profile for ship was prepared according to the preparation method of Example 1, except that the alloy was selected with the chemical components of Mn: 0.85%, Mg: 4.95%, and the content of B was 0.0035%.

[0076] Homogenization treatment: the temperature was 540 ℃ for 14 h.

[0077] The 45° convergence angle was designed for the inlet section of the mold.

[0078] The mold heating temperature was 450 ℃, the cast bar after homogenization treatment was heated to 460 ℃, and then extrusion was carried out at an extrusion speed of 0.5 m / min.

[0079] Annealing treatment: the 5083 aluminum alloy profile was subjected to two-stage annealing treatment, the first-stage annealing temperature was increased to 330 ℃ at a rate of 90 ℃ / h, the first-stage annealing holding temperature was 330 ℃ for 1 h, the second-stage annealing temperature was increased to 360 ℃ from 330 ℃ at a rate of 60 ℃ / h, and the second-stage annealing holding temperature was 360 ℃ for 0.5 h. Then air cooling to 25 ℃, to obtain the 5-series aluminum alloy profile DA1 for ship.

[0080] Comparative Example 2 The 5-series aluminum alloy profile for ship was prepared according to the preparation method of Example 1, except that the alloy was selected with the chemical components of Mn: 0.55%, Mg: 4.65%, and the content of B was 0.0035%.

[0081] Homogenization treatment: the temperature was 520 ℃ for 16 h.

[0082] The 45° convergence angle was designed for the inlet section of the mold.

[0083] The mold heating temperature was 460 ℃, the cast bar after homogenization treatment was heated to 420 ℃, and then extrusion was carried out at an extrusion speed of 1.5 m / min.

[0084] Annealing treatment: the 5083 aluminum alloy profile was subjected to two-stage annealing treatment, the first-stage annealing temperature was increased to 310 ℃ at a rate of 70 ℃ / h, the first-stage annealing holding temperature was 310 ℃ for 1.5 h, the second-stage annealing temperature was increased to 340 ℃ from 310 ℃ at a rate of 40 ℃ / h, and the second-stage annealing holding temperature was 340 ℃ for 1 h. Then air cooling to 25 ℃, to obtain the 5-series aluminum alloy profile DA2 for ship.

[0085] Comparative Example 3 The 5-series aluminum alloy profile for ship was prepared according to the preparation method of Example 1, except that the alloy was selected with the chemical components of Mn: 0.8%, Mg: 4.9%, and the content of B was 0.003%.

[0086] Homogenization treatment: temperature is 540℃ for 14h.

[0087] The mold inlet section is designed with a 45° convergence angle.

[0088] The mold heating temperature was 450°C, and the cast rod after homogenization treatment was heated to 460°C and then extruded at an extrusion speed of 0.5m / min.

[0089] Annealing treatment: The 5083 aluminum alloy profile was subjected to conventional annealing at 350°C for 2 hours, followed by air cooling to 25°C to obtain the 5 series aluminum alloy profile DA3 for marine applications.

[0090] Comparative Example 4 A 5 series aluminum alloy profile for ships was prepared according to the preparation method of Example 1, except that the alloy had a chemical composition of Mn: 0.8%, Mg: 4.9%, and a B content of 0.003%.

[0091] Homogenization treatment: temperature is 540℃ for 14h.

[0092] The thickness of the end working zone is 10mm, the thickness of the middle working zone is 27mm, and the mold inlet section is designed with a 62° convergence angle.

[0093] The mold heating temperature was 450°C, and the cast rod after homogenization treatment was heated to 460°C and then extruded at an extrusion speed of 1.0 m / min.

[0094] Annealing: The 5083 aluminum alloy profiles underwent a two-stage annealing process: heating from 20°C to 330°C at a 90°C / h ramp rate for the first annealing, with a hold at 330°C for 1 hour. The second annealing process involved heating from 330°C to 360°C at a 60°C / h ramp rate, with a hold at 360°C for 0.5 hours. The profiles were then air-cooled to 25°C to produce the DA4 5-series aluminum alloy profile for marine applications.

[0095] Comparative Example 5 A 5 series aluminum alloy profile for ships was prepared according to the preparation method of Example 1, except that the alloy had a chemical composition of Mn: 0.8%, Mg: 4.9%, and a B content of 0.003%.

[0096] Homogenization treatment: temperature is 540℃ for 14h.

[0097] The thickness of the extruded profile is 10mm, the thickness of the end working zone is 5.5mm, the thickness of the middle working zone is 13mm, and the die inlet section is designed with a 43° convergence angle.

[0098] The mold heating temperature is 450℃, the cast bar after homogenization treatment is heated to 460℃, and then extrusion is performed at an extrusion speed of 1.0 m / min.

[0099] Annealing treatment: the 5083 aluminum alloy profile is subjected to two-stage annealing treatment, and is heated to 330℃ at 20℃, the first-stage annealing heating rate is 90℃ / h, the first-stage annealing holding system is 1h at 330℃, the second-stage annealing heating system is heated to 360℃ from 330℃, the second-stage annealing heating rate is 60℃ / h, and the second-stage annealing holding system is 0.5h at 360℃. Then air cooling to 25℃, obtaining the 5 series aluminum alloy profile DA5 for ships.

[0100] The performance tests are performed on A1-A8 and DA1-DA5, as shown in Tables 1 and 2 Table 1 Performance test results Through the comparison of the examples and the comparative examples, it can be seen that the 5 series aluminum alloy profile for ships provided by the application can effectively improve the mechanical properties, welding coefficient and corrosion resistance of the alloy after optimizing the alloy composition.

[0101] After the two-stage annealing treatment of Examples 1-3, especially the further control of the heating rate, the second phase distribution in the 5 series aluminum alloy matrix is more uniform and dispersed, so that the strength at different positions on the thickness is uniform, and the maximum strength difference is less than 5MPa. The maximum strength difference on the thickness is too large, reaching 14MPa, because the second phase distribution in the matrix is not uniform due to the faster heating of the two-stage annealing process in Comparative Example 3.

[0102] Table 2 Profile size test results The profile size test results of Examples 1-5 and Comparative Examples 4-5 are shown in Table 2, and it can be found that the longitudinal bending degree of the profile is ≤1.5mm / m and the twist degree is ≤1.0mm / m by effectively controlling the working belt and the convergence angle of the flow guide mold.

[0103] The profile size test results of Examples 1-5 and Comparative Examples 4-5 are shown in Table 2, and it can be found that the longitudinal bending degree of the profile is ≤1.5mm / m and the twist degree is ≤1.0mm / m by effectively controlling the working belt and the convergence angle of the flow guide mold. Figure 2 and 3 It can be seen that the exfoliation corrosion of Example 3 provided by the application is better than that of Comparative Example 1, and the profile size test results of Examples 1-5 and Comparative Examples 4-5 are shown in Table 2. Figure 2 and 3 It can be seen that the bending degree and twist degree of Example 1 provided by the application are better than those of Comparative Example 4.

[0104] The above merely describes preferred embodiments of the present application, but the protection scope of the present application is not limited thereto, and any person skilled in the art, according to the technical scheme and inventive concept of the present application, can make equivalent replacements or changes within the technical scope disclosed by the present application, which should be covered within the protection scope of the present application.

Claims

1. A 5 series aluminum alloy profile for ships, characterized in that: The components and their weight percentages in the profile are: Si content ≤ 0.18%; Fe content ≤ 0.15%; Cu content ≤ 0.10%; Mn content is 0.6-0.8%; Mg content is 4.7-4.9%; Cr content is 0.05-0.25%; Zn content ≤ 0.20%; Ti content ≤ 0.15%; B content is 0.0005-0.003%; The content of other impurity elements is ≤0.05%; The total content of other impurity elements is ≤0.15%; The balance is Al.

2. A method for preparing the 5 series aluminum alloy profile for ships according to claim 1, characterized in that: The method comprises: Casting, homogenization, extrusion, annealing; The thickness L1 of the end working zone of the extrusion die is (0.4-0.5)×profile wall thickness, in mm, and the thickness L2 of the middle working zone of the extrusion die is profile wall thickness ±2, in mm.

3. The method according to claim 2, characterized in that The cross-sections of the mold are a first mold cross-section, a second mold cross-section, a third mold cross-section and a fourth mold cross-section; The cross section of the first mold is rectangular. In the length direction, one sixteenth of the total length of the left and right end sections is the end working zone, and the rest is the middle working zone. The second mold section is a pattern formed by two rectangles in vertical contact, the long midline of the first rectangle coincides with the wide midline of the second rectangle, one sixteenth of the total length of the left and right ends of the first rectangle is the end working zone, and the rest of the first rectangle is the middle working zone, one sixteenth of the total length of the right end of the second rectangle is the end working zone, and the rest of the second rectangle is the middle working zone; The third mold section consists of a third rectangle, a fourth rectangle and a fifth rectangle, the third rectangle is parallel to the fifth rectangle, the fourth rectangle is in perpendicular contact with the third rectangle, the fourth rectangle is in perpendicular contact with the fifth rectangle, the long midline of the third rectangle coincides with the wide midline of the fourth rectangle, the long midline of the fifth rectangle coincides with the wide midline of the fourth rectangle, the length and width of the third rectangle are the same as the length and width of the fifth rectangle, one sixteenth of the total length of the left and right ends of the third rectangle is the end working zone, the rest of the third rectangle is the middle working zone, one sixteenth of the total length of the left and right ends of the fifth rectangle is the end working zone, the rest of the fifth rectangle is the middle working zone, and the fourth rectangle is the middle working zone; The fourth mold section is composed of a sixth rectangle, a seventh rectangle and an eighth rectangle. The sixth rectangle is in vertical contact with the seventh rectangle, and the eighth rectangle is in vertical contact with the seventh rectangle. The length of the width midline of the sixth rectangle and the end close to the seventh rectangle is equal to the length of the sixth rectangle, the length of the width midline of the eighth rectangle and the end close to the seventh rectangle is equal to the length of the eighth rectangle, the length and width of the sixth rectangle are the same as the length and width of the eighth rectangle, the length of the sixth rectangle is greater than one sixteenth of the length of the seventh rectangle, one sixteenth of the total length of the left and right ends of the seventh rectangle is the end working zone, and the rest of the seventh rectangle is the middle working zone, one sixteenth of the total length of the sixth rectangle away from the end of the seventh rectangle is the end working zone, and the rest of the sixth rectangle is the middle working zone, one sixteenth of the total length of the eighth rectangle away from the end of the seventh rectangle is the end working zone, and the rest of the eighth rectangle is the middle working zone.

4. The method according to claim 2, characterized in that The convergence angle at the guide die of the extrusion die is 45°-60°.

5. The method according to claim 2, characterized in that The extrusion conditions include: a mold heating temperature of 450-480°C, heating the homogenized cast rod to 420-460°C for extrusion, an extrusion ratio of 20-35, an extrusion speed of 0.5-1.5 m / min, a water mist quenching method, and then online stretching and straightening with a stretching amount of 0.5-1.5%. The thickness of the extruded profile is 10-30 mm and the maximum width is 100-600 mm.

6. The method according to claim 2, characterized in that The casting conditions include: preheating the aluminum ingot and the master alloy at 100-200°C, placing the aluminum ingot in a melting furnace, heating it to 800-850°C, and after the aluminum ingot is melted, lowering the temperature to 730-760°C, then filling in Al-Fe, Al-Si, Al-Mn, Al-Cr, and Al-B master alloys, and performing electromagnetic stirring after all are melted for 30-60 minutes. Subsequently, a magnesium ingot is added, and the melt is allowed to stand for 10-14 minutes. The melt is degassed and refined by a powder spraying method, and surface slag is removed by mechanical skimming. The melt is allowed to stand for 20-25 minutes. Semi-continuous casting is performed when the melt temperature drops to 715-730°C. During the casting process, Al-Ti-B wire is added to refine the alloy.

7. The method according to claim 2, characterized in that The homogenization treatment conditions include: treating at a temperature of 520-540° C. for 14-16 hours, using water mist cooling at a cooling rate of 15-20° C. / min, and cooling to 20-30° C.

8. The method according to claim 2, characterized in that The annealing conditions include: performing a two-stage annealing treatment on the profile, wherein the first-stage annealing temperature rises from 20-25°C to 310-330°C, the first-stage annealing temperature rise rate is 70-90°C / h, the first-stage annealing heat preservation system is kept at 310-330°C for 1-1.5h, the second-stage annealing temperature rises from 310-330°C to 340-360°C, the second-stage annealing temperature rise rate is 40-60°C / h, the second-stage annealing heat preservation system is kept at 340-360°C for 0.5-1h, and air cooling is performed to 20-30°C to obtain the 5 series aluminum alloy profile for ships.

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