CN113957306B - Aluminum alloy section bar, preparation method thereof and application thereof in rail transit electric screen cabinet - Google Patents
Aluminum alloy section bar, preparation method thereof and application thereof in rail transit electric screen cabinet Download PDFInfo
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Abstract
The invention discloses an aluminum alloy section bar and a preparation method and application thereof, wherein the aluminum alloy section bar comprises the following components: 5.5 to 6.5 percent of Zn, 0.5 to 0.9 percent of Mg, 0.05 to 0.12 percent of Cu, 0.1 to 0.28 percent of Mn, 0.1 to 0.15 percent of Cr, 0.15 to 0.18 percent of Zr, 0.01 to 0.03 percent of Ti, less than or equal to 0.12 percent of Fe, less than or equal to 0.06 percent of Si, the balance of Al, and the mass ratio of Zn to Mg is less than 13. The aluminum alloy profile has the advantages of high strength, good plasticity, good stress corrosion resistance and the like, is a novel alloy material with high strength, good plasticity and good stress corrosion resistance, can be used for rail transit electric screen cabinets, can meet the use requirements of the rail transit electric screen cabinets, can improve the reliability of the rail transit electric screen cabinets, and has high use value and good application prospect.
Description
Technical Field
The invention belongs to the technical field of aluminum alloy processing, and relates to an aluminum alloy section, a preparation method thereof and application thereof in rail transit electric cubicles.
Background
The rail transit is an important component in the transportation industry, and directly influences the travel, work and life of residents. With the rapid development of rail transit, high-speed trains and intercity rail trains taking aluminum alloy as components such as vehicle bodies, frames and chassis are put into use in succession, wherein the aluminum alloy has different requirements on performance indexes of the aluminum alloy based on different technical indexes required by different application scenes in the actual application of the rail transit. When the aluminum alloy is used for preparing a rail transit vehicle body, in order to improve the adaptability of the vehicle body to high-speed lines, multi-bend lines, undulating lines and severe environments, the aluminum alloy is required to have performance indexes such as high strength and toughness, corrosion resistance, fatigue resistance, weldability and the like, wherein the tensile strength is greater than 360MPa, the four-point bending stress corrosion is not cracked for 30 days, and the fracture toughness is greater than 45 MPa.m 1/2 (ii) a When the electric screen cabinet is used for preparing the rail transit electric screen cabinet, the electric screen cabinet is usually suspended below a train body, so that the reliability of the electric screen cabinet is also important to the running safety of a train, and the aluminum alloy is required to have the following performance indexes: the tensile strength reaches 310MPa, and the elongation after fracture is not lower than 8.0 percent; the slow strain rate tensile stress corrosion sensitive factor is less than 5%, and obvious spalling corrosion does not occur; under the condition that the stress ratio is 0.1, the fatigue limit is not lower than 120MPa. In addition, the strength of the existing aluminum alloy material can meet the international requirements, but the existing aluminum alloy material still has the defects of poor toughness, low stress corrosion resistance, low fatigue resistance and the like, and also has the defect of high stress corrosion sensitivity, so that the safety risk is increased, and the use requirement of the rail transit electric screen cabinet is difficult to meet. For example, 7003 aluminum alloy is a typical Al-Zn-Mg alloy, and high Mg and Zn contents are beneficial to improving the strength, but increase the corrosion tendency; although the addition of Cu element lowers the weldability and combines with Fe element to form Al 7 Cu 2 Fe impurity phase, but can increase the solid solubility of Zn and Mg and improve the electrode potential (entering MgZn through diffusion action) 2 Precipitated phases); the addition of Mn and Cr elements in proper amount can form fine dispersed phase with Al matrix, prevent dislocation motion, and inhibit recrystallization during hot working and heat treatmentThe quenching sensitivity is greatly increased, and meanwhile, a coarse equilibrium phase is formed due to excessive contents of Mn and Cr elements, so that the fatigue resistance and the fracture toughness are reduced; the addition of Zr can play a role in inhibiting recrystallization, improve the high-temperature stability of the alloy and inhibit the coarsening of crystal grains; fe. Si impurity elements are combined with an Al matrix to form a hard and brittle phase, which is unfavorable for the mechanical property of the alloy, so that the content of the Si impurity elements needs to be controlled. Therefore, in order to overcome the disadvantages of poor toughness, low stress corrosion resistance and fatigue resistance of the existing Al-Zn-Mg alloy, the aluminum alloy section with high strength, good plasticity and good stress corrosion resistance is obtained, and the aluminum alloy section has very important significance for meeting the use requirements of the rail transit electric screen cabinet and improving the reliability of the rail transit electric screen cabinet.
Disclosure of Invention
The invention aims to overcome the defects of the prior art and provides an aluminum alloy section with high strength, good plasticity and good stress corrosion resistance, a preparation method thereof and application of the aluminum alloy section as a raw material in rail transit electric screen cabinets.
In order to solve the technical problems, the invention adopts the technical scheme that:
the aluminum alloy profile comprises the following components in percentage by mass: 5.5 to 6.5 percent of Zn, 0.5 to 0.9 percent of Mg, 0.05 to 0.12 percent of Cu, 0.1 to 0.28 percent of Mn, 0.1 to 0.15 percent of Cr, 0.15 to 0.18 percent of Zr, 0.01 to 0.03 percent of Ti, less than or equal to 0.12 percent of Fe, less than or equal to 0.06 percent of Si, and the balance of Al; in the aluminum alloy section, the mass ratio of Zn to Mg is less than 13.
In the aluminum alloy section, the mass ratio of Zn to Mg is further improved to be 6.2-12.
In the aluminum alloy section, the mass ratio of Zn to Mg is further improved to be 6.4-10.
As a general technical concept, the present invention also provides a method for preparing the aluminum alloy profile, comprising the steps of:
(1) Smelting: mixing the raw materials according to the mass percentage of each component of the aluminum alloy section, and heating to melt;
(2) Degassing and deslagging: adding a refining agent into the aluminum alloy liquid melted in the step (1) for degassing, filtering and deslagging;
(3) Casting: casting and forming the aluminum alloy liquid obtained after degassing and deslagging in the step (2) to obtain an aluminum ingot;
(4) Homogenization treatment: homogenizing the aluminum ingot obtained in the step (3);
(5) Sawing and turning a leather: sawing and turning the homogenized aluminum ingot in the step (4);
(6) Heat preservation and extrusion: carrying out heat preservation treatment and extrusion forming on the aluminum ingot subjected to saw cutting and skinning in the step (5);
(7) Sawing: sawing the section bar obtained by extrusion molding in the step (6);
(8) Solution treatment: carrying out solution treatment on the section obtained after sawing in the step (7), and quenching after the solution treatment is finished;
(9) Pre-stretching: straightening the section bar obtained after quenching in the step (8);
(10) Aging treatment: and (4) carrying out two-stage aging treatment on the section obtained after the straightening treatment in the step (9), and cooling to obtain the aluminum alloy section.
In the above preparation method, further improvement is that, in the step (7), the saw cutting is to saw the sectional material into the sectional material with the length of 4 m.
In the preparation method, the preparation method is further improved, in the step (8), the solution treatment is carried out at the temperature of 470-480 ℃; the medium adopted for quenching is water.
The preparation method is further improved, and in the step (9), the stretching amount of the profile is controlled to be 1.5% -2% in the straightening treatment process.
In the step (10), the two-stage aging treatment is to preserve heat of the section at the aging temperature of 100-110 ℃ for 5-8 h, and then preserve heat at the aging temperature of 155-175 ℃ for 4-24 h.
In the preparation method, the preparation method is further improved, in the step (1), al-Ti-B alloy is used as a refiner; the heating is to heat the mixed material to 750-780 ℃ and keep the temperature for 6-8 h;
in the step (2), the refining agent is chloride; the chlorine salt is at least one of potassium chloride and magnesium chloride; the addition amount of the refining agent is 1-1.5% of the mass of the aluminum alloy liquid melted in the step (1);
in the step (3), the casting molding temperature is 710-730 ℃; the aluminum ingot is cylindrical, and the diameter of the aluminum ingot is 200-300 mm;
in the step (4), the homogenization treatment is to keep the temperature at 460-470 ℃ for 4-24 h;
in the step (6), the heat preservation treatment is to preserve heat for 3 hours at the temperature of 440-470 ℃; the technological parameters in the extrusion forming process are as follows: the temperature of the die is 440-480 ℃, the temperature of the extrusion cylinder is 370-420 ℃, the temperature of the extrusion piece after being taken out of the die is 475-485 ℃, and the extrusion speed is 2-5 m/min; in the pressure forming process, an alloy with yield strength lower than 90MPa is used as a dummy ingot; the alloy with the yield strength lower than 90MPa is a 1xxx series alloy or a 6xxx series alloy; the 6xxx series alloy is one of 6061, 6063, 6005A and 6082; the 1 xxx-series alloy is one of 1060, 1070; the width of the section obtained after extrusion molding is 75mm, the thickness of the section is 6mm, and the section is L-shaped; and cooling the section bar obtained after extrusion forming by adopting water mist.
As a general technical concept, the invention also provides application of the aluminum alloy section or the aluminum alloy section prepared by the preparation method as a raw material in rail transit electric cabinets.
Compared with the prior art, the invention has the advantages that:
(1) Aiming at the performance characteristics of high strength, good plasticity, good stress corrosion resistance and the like which cannot be simultaneously met in the existing aluminum alloy section, the invention provides an aluminum alloy section which comprises the following components in percentage by mass: 5.5 to 6.5 percent of Zn, 0.5 to 0.9 percent of Mg, 0.05 to 0.12 percent of Cu, 0.1 to 0.28 percent of Mn, 0.1 to 0.15 percent of Cr, 0.15 to 0.18 percent of Zr, 0.01 to 0.05 percent of Ti, less than or equal to 0.12 percent of Fe, less than or equal to 0.06 percent of Si, and the balance of Al. In the invention, the content of each component is optimized, the aluminum alloy section bar which has the advantages of high strength, good plasticity, good stress corrosion resistance and the like is obtained, specifically, the content of Zn and Mg is optimized, wherein the content of Zn is 5.5-6.5%, and the content of Mg is 0.5-0.9%, and the excellent toughness and stress corrosion resistance can be ensured while the strength of the alloy material is improved by improving the content of Zn and reducing the content of Mg, namely improving the mass ratio of Zn and Mg; meanwhile, the content of other components is optimized correspondingly, for example, the content of Mn and Cr is optimized, wherein the content of Mn is 0.1-0.28 percent, the content of Cr is 0.1-0.15 percent, and the corrosion resistance of a second phase is improved by optimizing the content of Mn and Cr, so that the aluminum alloy section provided by the invention has the advantages of high strength, good plasticity, good stress corrosion resistance and the like. Compared with the existing Al-Zn-Mg alloy section, the aluminum alloy section has the advantages of high strength, good plasticity, good stress corrosion resistance and the like, is a novel alloy material with high strength, good plasticity and good stress corrosion resistance, can meet the use requirement of the rail transit electric screen cabinet and improve the reliability of the rail transit electric screen cabinet, and has high use value and good application prospect.
(2) In the aluminum alloy section bar, the mass ratio of Zn to Mg is optimized to be 6.2-12, so that the strength of an alloy material is improved, and the better toughness and stress corrosion resistance can be ensured, because if the mass ratio of Zn to Mg is too low, T (Al) is easily formed in the alloy 2 Mg 3 Zn 3 ) Phase, T phase strengthening effect is better than MgZn 2 The strengthening effect of the phases is poor, so that the strength cannot be effectively improved due to a low mass ratio, and meanwhile, the hardenability of the alloy is reduced due to a relatively high Mg content, so that the improvement of the toughness and the stress corrosion resistance of the alloy material is not facilitated; if the mass ratio of Zn to Mg is too high (e.g., above 13), the stress corrosion resistance of the alloy deteriorates, and it becomes difficult to obtain an alloy material satisfying both high strength, good plasticity, and good stress corrosion resistance. In particular, when the mass ratio of Zn to Mg is 6.4 to 10, the aluminum alloy section of the invention hasHigher strength, better plasticity and stronger stress corrosion resistance.
(3) The invention provides a preparation method of an aluminum alloy section, which adopts a two-stage aging process and can change a crystal boundary precipitation phase MgZn on the premise of not losing a large amount of mechanical properties 2 The distribution condition of the aluminum alloy is reduced, the continuity of the aluminum alloy is reduced, a channel of a corrosive medium is blocked, and the corrosion resistance of the alloy is improved, so that a novel alloy material which has high strength, good plasticity and good stress corrosion resistance is prepared, and meanwhile, compared with a conventional three-stage aging process, the two-stage aging process adopted in the invention not only can prepare an aluminum alloy section with better stress corrosion resistance, but also can shorten the preparation time, improve the preparation efficiency and reduce the preparation cost.
(4) In the preparation method of the aluminum alloy section bar, the refining agent such as chloride (potassium chloride and magnesium chloride) is adopted, and the addition amount of the refining agent is optimized to be 1-1.5% of the mass of the molten aluminum alloy liquid, so that the gas, impurities and harmful elements in the melt can be removed, and the excellent performance of the alloy material can be ensured while the content of harmful impurities is reduced.
(5) In the preparation method of the aluminum alloy section, the stretching amount of the section is controlled to be 1.5-2% in the straightening treatment process, dislocation can be formed in the section, and the section can be used as a heterogeneous nucleation point in the aging process to promote the precipitation of a second phase, thereby being beneficial to further improving the strength of an alloy material.
Drawings
In order to make the objects, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the drawings in the embodiments of the present invention.
FIG. 1 is a graph comparing the exfoliation corrosion morphology of the aluminum alloy shapes prepared in examples 1-2 of the present invention and comparative examples 1-2.
FIG. 2 is a graph comparing the exfoliation corrosion patterns of the aluminum alloy sections produced in example 2 of the present invention and the aluminum alloy sections produced in comparative examples 3 to 5.
Detailed Description
The invention is further described below with reference to the drawings and the specific preferred embodiments, without thereby limiting the scope of protection of the invention.
The materials and equipment used in the following examples are commercially available.
Example 1
An aluminum alloy profile comprises the following components in percentage by mass: 5.5 percent of zinc (Zn), 0.85 percent of magnesium (Mg), 0.12 percent of copper (Cu), 0.22 percent of manganese (Mn), 0.13 percent of chromium (Cr), 0.16 percent of zirconium (Zr), 0.03 percent of titanium (Ti), less than or equal to 0.12 percent of iron (Fe), less than or equal to 0.06 percent of silicon (Si), and the balance of aluminum (Al).
The preparation method of the aluminum alloy profile comprises the following steps:
(1) Smelting: mixing aluminum ingots, magnesium ingots and other intermediate alloys according to the mass percentage of each component of the alloy, heating to 760 ℃ for melting, preserving heat for 6 hours, and adding Al-Ti-B alloy as a refiner, aiming at improving the nucleation rate in the solidification process so as to realize the effect of grain refinement.
(2) Degassing and deslagging: according to the addition amount of 1.2 percent of the mass of the molten aluminum alloy liquid, a refining agent (magnesium chloride) is added to degas the molten aluminum alloy liquid, and slag is removed by filtration.
(3) Casting: and pouring the aluminum alloy liquid subjected to degassing and deslagging into a mold at the casting temperature of 720 ℃, and cooling to obtain a cylindrical aluminum ingot with the diameter of 250 mm.
(4) Homogenizing: and (3) placing the aluminum ingot at 465 ℃ and preserving heat for 4h for homogenization treatment.
(5) Sawing and turning a leather: and transferring the homogenized aluminum ingot to a sawing machine and a lathe for sawing and turning.
(6) Heat preservation and extrusion: keeping the temperature of the aluminum ingot after the peeling at 440 ℃ for 3h, and then extruding, wherein the extrusion parameters are as follows: the temperature of the die is 460 ℃, the temperature of the extrusion barrel is 420 ℃, the temperature of the extrusion part is 480 ℃, the extrusion speed is 2m/min, the extrusion is carried out to form an angular section of 75 x 6mm, and the angular section is cooled by water mist. The dummy ingot adopted in the extrusion process is 6061 aluminum alloy.
(7) Sawing: the extruded profile was sawn into profiles of 4m length.
(8) Solution treatment: carrying out solution treatment on the sawed alloy section at the temperature of 470 ℃; immediately quenching the aluminum profile by water after the solution treatment.
(9) Pre-stretching: the profile was straightened on a straightener with a draw of 1.5%.
(10) Aging treatment: and (3) carrying out two-stage aging treatment on the aluminum profile after the straightening treatment, wherein the first-stage aging temperature is 105 ℃, and the heat preservation time is 6h, and the second-stage failure temperature is 155 ℃, and the heat preservation time is 12h, so as to obtain the aluminum alloy profile.
The aluminum alloy section prepared by the embodiment is used as a raw material to be applied to a rail transit electric screen cabinet.
Example 2
An aluminum alloy profile comprises the following components in percentage by mass: 6.0 percent of Zn, 0.85 percent of Mg, 0.12 percent of Cu, 0.22 percent of Mn, 0.13 percent of Cr, 0.16 percent of Zr, 0.03 percent of Ti, less than or equal to 0.12 percent of Fe, less than or equal to 0.06 percent of Si, and the balance of Al.
The preparation method of the aluminum alloy profile comprises the following steps:
(1) Smelting: mixing an aluminum ingot, a magnesium ingot and other intermediate alloys according to the mass percentage of each component of the alloy, heating to 760 ℃, preserving heat for 6 hours, and adding Al-Ti-B alloy as a refiner.
(2) Degassing and deslagging: according to the addition amount of 1.2 percent of the mass of the molten aluminum alloy liquid, a refining agent (magnesium chloride) is added to degas the molten aluminum alloy liquid, and slag is removed by filtration.
(3) Casting: and pouring the aluminum alloy liquid subjected to degassing and deslagging into a mold at the casting temperature of 720 ℃, and cooling to obtain a round aluminum ingot with the diameter of 250 mm.
(4) Homogenizing: and (3) placing the aluminum ingot at 465 ℃ and preserving heat for 4h for homogenization treatment.
(5) Sawing and turning a leather: and transferring the homogenized aluminum ingot to a sawing machine and a lathe for sawing and turning.
(6) Heat preservation and extrusion: keeping the temperature of the aluminum ingot after the peeling at 440 ℃ for 3h, and then extruding, wherein the extrusion parameters are as follows: the temperature of the die is 460 ℃, the temperature of the extrusion barrel is 420 ℃, the temperature of the extrusion part is 480 ℃, the extrusion speed is 2m/min, the extrusion is carried out to form an angular section of 75 x 6mm, and the angular section is cooled by water mist. The dummy ingot adopted in the extrusion process is 6061 aluminum alloy.
(7) Sawing: the extruded profile was sawn into profiles of 4m length.
(8) Solution treatment: carrying out solution treatment on the alloy at the temperature of 470 ℃; after the aluminum profile is subjected to solution treatment, the aluminum profile is immediately quenched by water.
(9) Pre-stretching: the profile was straightened on a straightener with a draw of 1.5%.
(10) And (3) aging treatment: and (3) carrying out two-stage aging treatment on the aluminum profile after the straightening treatment, wherein the first-stage aging temperature is 105 ℃, and the heat preservation time is 6h, and the second-stage failure temperature is 155 ℃, and the heat preservation time is 12h.
The aluminum alloy section prepared by the embodiment is used as a raw material to be applied to rail transit electric cabinets.
Comparative example 1
An aluminum alloy profile comprises the following components in percentage by mass: 6.5 percent of Zn, 0.50 percent of Mg, 0.12 percent of Cu, 0.22 percent of Mn, 0.13 percent of Cr, 0.16 percent of Zr, 0.03 percent of Ti, less than or equal to 0.12 percent of Fe, less than or equal to 0.06 percent of Si, and the balance of Al.
The preparation method of the aluminum alloy profile comprises the following steps:
(1) Smelting: mixing aluminum ingots, magnesium ingots and other intermediate alloys according to the mass percentage, heating to 760 ℃, preserving heat for 6 hours, and adding Al-Ti-B alloy as a refiner.
(2) Degassing and deslagging: according to the addition amount of 1.2 percent of the mass of the molten aluminum alloy liquid, a refining agent (magnesium chloride) is added to degas the molten aluminum alloy liquid, and the slag is removed by filtration.
(3) Casting: and (3) pouring the aluminum alloy liquid subjected to degassing and deslagging into a mould at the casting temperature of 720 ℃, and cooling to obtain a round aluminum ingot with the diameter of 250 mm.
(4) Homogenizing: and (3) placing the aluminum ingot at 465 ℃ and preserving heat for 4h for homogenization treatment.
(5) Sawing and turning a leather: and transferring the homogenized aluminum ingot to a sawing machine and a lathe for sawing and turning.
(6) Heat preservation and extrusion: keeping the temperature of the aluminum ingot after the peeling at 440 ℃ for 3h, and then extruding, wherein the extrusion parameters are as follows: the temperature of the die is 460 ℃, the temperature of the extrusion barrel is 420 ℃, the temperature of the extrusion part is 480 ℃, the extrusion speed is 2m/min, the extrusion is carried out to form an angular section of 75 x 6mm, and the angular section is cooled by water mist. The dummy ingot adopted in the extrusion process is 6061 aluminum alloy.
(7) Sawing: the profile was sawn into profiles of 4m length.
(8) Solution treatment: carrying out solution treatment on the alloy at the temperature of 470 ℃; immediately quenching the aluminum profile by water after the solution treatment.
(9) Pre-stretching: the profile was straightened on a straightener with a draw of 1.5%.
(10) Aging treatment: and (3) carrying out two-stage aging treatment on the aluminum profile after the straightening treatment, wherein the first-stage aging temperature is 105 ℃, and the heat preservation time is 6h, and the second-stage failure temperature is 155 ℃, and the heat preservation time is 12h.
Comparative example 2
An aluminum alloy profile comprises the following components in percentage by mass: 6.0 percent of Zn, 0.85 percent of Mg, 0 percent of Cu, 0.22 percent of Mn, 0.13 percent of Cr, 0.16 percent of Zr, 0.03 percent of Ti, less than or equal to 0.12 percent of Fe, less than or equal to 0.06 percent of Si, and the balance of Al.
The preparation method of the aluminum alloy profile comprises the following steps:
(1) Smelting: mixing aluminum ingots, magnesium ingots and other intermediate alloys according to the mass percentage, heating to 760 ℃, preserving heat for 6 hours, and adding Al-Ti-B alloy as a refiner.
(2) Degassing and deslagging: according to the addition amount of 1.2 percent of the mass of the molten aluminum alloy liquid, a refining agent (magnesium chloride) is added to degas the molten aluminum alloy liquid, and slag is removed by filtration.
(3) Casting: and pouring the aluminum alloy liquid subjected to degassing and deslagging into a mold at the casting temperature of 720 ℃, and cooling to obtain a round aluminum ingot with the diameter of 250 mm.
(4) Homogenizing: and (3) placing the aluminum ingot at 465 ℃ and preserving heat for 4 hours for homogenization treatment.
(5) Sawing and turning a leather: and transferring the homogenized aluminum ingot to a sawing machine and a lathe for sawing and turning.
(6) Heat preservation and extrusion: keeping the temperature of the aluminum ingot after the peeling at 440 ℃ for 3h, and then extruding, wherein the extrusion parameters are as follows: the temperature of the die is 460 ℃, the temperature of the extrusion cylinder is 420 ℃, the temperature of the extrusion part out of the die is 480 ℃, the extrusion speed is 2m/min, and the extrusion part is extruded into 75-6 mm angular sections and cooled by water mist. The dummy ingot adopted in the extrusion process is 6061 aluminum alloy.
(7) Sawing: the profile was sawn into profiles of 4m length.
(8) Solution treatment: carrying out solution treatment on the alloy at the temperature of 470 ℃; immediately quenching the aluminum profile by water after the solution treatment.
(9) Pre-stretching: the profile was straightened on a straightener with a draw of 1.5%.
(10) Aging treatment: and (3) carrying out two-stage aging treatment on the aluminum profile after the straightening treatment, wherein the first-stage aging temperature is 105 ℃, and the heat preservation time is 6h, and the second-stage failure temperature is 155 ℃, and the heat preservation time is 12h.
Comparative example 3
An aluminum alloy profile, substantially the same as example 2, except that: in comparative example 3, the content of Zr element by mass was changed to 0%, and the reduced portion was supplemented with Al, that is, the content of Al was increased.
Comparative example 4
An aluminium alloy profile substantially as in example 2, except that: in comparative example 4, the content of Zr element by mass was changed to 0.12%, and the decrease portion was supplemented with Al, that is, the content of Al was increased.
Comparative example 5
An aluminium alloy profile substantially as in example 2, except that: in comparative example 5, the content of Zr element by mass was changed to 0.20%, and the increased portion was shared by Al, i.e., the content of Al was decreased.
FIG. 1 is a graph comparing the exfoliation corrosion morphology of the aluminum alloy shapes prepared in examples 1-2 of the present invention and comparative examples 1-2. In FIG. 1, a-d correspond to the aluminum alloy shapes obtained in examples 1-3 and comparative example 1 in this order. As can be seen from fig. 1, in example 1 (fig. 1 a), approximately half of the surface of the extruded profile is bubbled, the surface of the lower left corner is delaminated, part of the surface layer tissue falls off, and a small part of the internal tissue is exposed in the corrosive liquid, so that the peeling corrosion is not serious, the corrosion products are few, and the corrosion grade is EA; example 2 (fig. 1 b) the surface of the extruded profile only shows small area blisters on both sides in the extrusion direction, with a few pitting holes in the middle, almost no spalling corrosion products, corrosion rating PC; the extruded section of comparative example 1 (fig. 1 c) has obvious spalling corrosion, no metallic luster on the surface, severe bubbling and delamination of surface tissues, pulverization on part of the surface, exposure of a large amount of internal tissues in corrosive solution, accelerated spalling corrosion of parts in the alloy, more corrosion products and corrosion grade reaching EB. The surface of the alloy extruded profile of comparative example 2 (fig. 1 d) containing no Cu showed only slight bubbling at the edges of the seal, most of the surface remained metallic, the surface of the alloy was hardly corroded, and the corrosion rating was N.
FIG. 2 is a graph comparing the exfoliation corrosion morphology of the aluminum alloy sections produced in example 2 of the present invention and the aluminum alloy sections produced in comparative examples 3-5. In FIG. 2, a-d correspond to the aluminum alloy sections prepared in comparative example 3, comparative example 4, example 2, and comparative example 5, in this order. As can be seen from fig. 2, the aluminum alloy profile obtained in example 2 of the present invention has a relatively low degree of exfoliation corrosion (fig. 2 c), wherein, when Zr element is not added (comparative example 3, fig. 2 a), the surface of the sample is grayish black after soaking for 48h, no obvious bubbling is caused, only a few pitting holes are present, and the corrosion grade is N; when the Zr content is 0.12 wt% (fig. 2b, comparative example 4), the surface of the alloy sample has discontinuous corrosion, part of the surface structure falls off, the inner layer structure is not layered, the peeling corrosion is not obvious, the pitting corrosion is mainly used, and the corrosion grade is PC; when the content of Zr element was increased to 0.20wt.% (FIG. 2d, comparative example 5), some surface was cracked and delaminated by bubbling, and some exfoliation corrosion occurred, and the corrosion products were less, and the corrosion grade was EA, because as the content of Zr element was increased, the crystal grains were more refined, the number of grain boundaries in the same volume was larger, and the grain boundary was larger in the same volumeThe more non-precipitation zone (PFZ) formed after two-stage aging, PFZ and MgZn 2 Phase composition microbattery accelerates MgZn 2 Phase corrosion, and therefore, the degree of exfoliation corrosion becomes severe as the content of Zr element increases.
As can be seen from the results in fig. 1 and 2, the change in alloy composition has a large influence on exfoliation corrosion. In the Al-Zn-Mg- (Cu) alloy, the electrode potential of the substrate is-0.68V 2 The electrode potential of the phase was-0.86V, and the electrode potential of the non-precipitated zone (PFZ) was-0.57V. MgZn in alloy 2 The more phases are precipitated, the larger the potential difference with the matrix at the grain boundary, and the larger the driving force for corrosion. Although the grain boundary precipitated phase distribution is discontinuous for the alloy in the two-stage aging state, with the prolonging of the corrosion time, a corrosion channel is gradually formed at the grain boundary, and intergranular corrosion and even peeling corrosion are caused; the addition of Cu may agglomerate with Fe impurity in the alloy to form Al in the grain boundary 7 Cu 2 Fe phase, al 7 Cu 2 Fe is more than Al matrix and MgZn 2 Electrode potential correction of the phase as a cathode phase, accelerating MgZn 2 And thus exfoliation corrosion of the Cu-containing alloy extruded profile is more severe than when Cu is not contained. The influence of Zr element on the exfoliation corrosion performance is in an inseparable relationship with the microstructure of the alloy.
TABLE 1 tensile mechanical Properties at Room temperature of the aluminum alloy sections prepared in inventive examples 1-2 and comparative examples 1-5
| Number of | Tensile strength/MPa | Yield strength/MPa | Elongation/% of |
| Example 1 | 363 | 311 | 9.5 |
| Example 2 | 387 | 322 | 9.2 |
| Comparative example 1 | 316 | 262 | 11.4 |
| Comparative example 2 | 378 | 318 | 8.7 |
| Comparative example 3 | 329 | 279 | 12.2 |
| Comparative example 4 | 346 | 286 | 10.0 |
| Comparative example 5 | 396 | 338 | 7.4 |
TABLE 2 statistics of stress corrosion susceptibility factors for aluminum alloy sections prepared in inventive examples 1-2 and comparative examples 1-5
| Numbering | I SSRT/％ |
| Example 1 | 4.9 |
| Example 2 | 4.8 |
| Comparative example 1 | 4.7 |
| Comparative example 2 | 5.9 |
| Comparative example 3 | 7.7 |
| Comparative example 4 | 6.4 |
| Comparative example 5 | 3.4 |
As can be seen from tables 1 and 2, the mechanical properties of the aluminum alloy profiles of comparative example 2 and comparative examples 1 to 5 can be seen: the strength of the Al-Zn-Mg alloy is not obviously improved by simply increasing the Zn content, and in the comparative example 1, when the mass ratio of Zn to Mg is improved to 13, the tensile strength of the obtained aluminum alloy section is only 316MPa, and the requirement of the tensile strength of 360MPa can not be obviously met; while the comprehensive change of the contents of Mg and Zn elements greatly improves the alloy strength, for example, in the embodiment 2 of the invention, the tensile strength of the obtained aluminum alloy section (Zn 6.0 percent and Mg 0.85 percent) can reach 387MPa, and obviously, the strength of the aluminum alloy section with the mass ratio of Zn to Mg less than 13 can better meet the actual requirement. Meanwhile, as can be seen from the mechanical properties of the aluminum alloy profiles in example 2 and comparative example 2, the Cu content is increased from 0wt.% to 0.12wt.%, and the tensile strength and elongation of the alloy do not change much. The mechanical properties of the aluminum alloy sections in comparative example 2 and comparative examples 3-5 show that the tensile strength of the alloy is improved along with the increase of the Zr content. When the Zr element is not added, the tensile strength of the alloy is 329MPa, the tensile strength reaches 346MPa when the Zr element content is 0.12wt.%, and when the Zr content is continuously added to 0.16wt.% and 0.20wt.%, the tensile strength reaches 387MPa and 396MPa respectively, but the elongation rate is reduced along with the increase of the Zr content. In addition, when the content of the Zr element is lower than 0.12wt.%, the stress corrosion sensitivity factor is larger than 5%, and the Zr element does not have good stress corrosion resistance and can not meet the actual requirement.
From the results, the aluminum alloy section bar is a novel Al-Zn-Mg alloy section bar which has the characteristics of high strength, good plasticity, good corrosion resistance and the like, can be used for rail transit electric screen cabinets, and has wide application prospects.
The above examples are merely preferred embodiments of the present invention, and the scope of the present invention is not limited to the above examples. All technical schemes belonging to the idea of the invention belong to the protection scope of the invention. It should be noted that modifications and adaptations to those skilled in the art without departing from the principles of the present invention should also be considered as within the scope of the present invention.
Claims (6)
1. The preparation method of the aluminum alloy profile is characterized by comprising the following steps of:
(1) Smelting: mixing various raw materials according to the mass percentage of each component of the aluminum alloy section, and heating to melt;
(2) Degassing and deslagging: adding a refining agent into the aluminum alloy liquid melted in the step (1) for degassing, filtering and deslagging; the refining agent is chlorine salt; the chlorine salt is at least one of potassium chloride and magnesium chloride; the addition amount of the refining agent is 1-1.5% of the mass of the aluminum alloy liquid melted in the step (1);
(3) Casting: casting and molding the aluminum alloy liquid obtained by degassing and deslagging in the step (2) to obtain an aluminum ingot;
(4) Homogenizing: homogenizing the aluminum ingot obtained in the step (3);
(5) Sawing and turning a leather: sawing and turning the homogenized aluminum ingot in the step (4);
(6) Heat preservation and extrusion: carrying out heat preservation treatment and extrusion forming on the aluminum ingot subjected to saw cutting and skinning in the step (5);
(7) Sawing: sawing the section bar obtained by extrusion molding in the step (6);
(8) Solution treatment: carrying out solution treatment on the section obtained after sawing in the step (7), and quenching after the solution treatment is finished; the solution treatment is carried out at the temperature of 470-480 ℃;
(9) Pre-stretching: straightening the section bar obtained after quenching in the step (8);
(10) Aging treatment: performing two-stage aging treatment on the section obtained after the straightening treatment in the step (9), and cooling to obtain an aluminum alloy section; the two-stage aging treatment is to preserve heat of the section for 5 to 8 hours at the aging temperature of 100 to 110 ℃ and then preserve heat for 4 to 24 hours at the aging temperature of 155 to 175 ℃;
the aluminum alloy profile comprises the following components in percentage by mass: 6.0 percent of Zn, 0.85 percent of Mg, 0.12 percent of Cu, 0.22 percent of Mn, 0.13 percent of Cr, 0.16 percent of Zr, 0.03 percent of Ti, less than or equal to 0.12 percent of Fe, less than or equal to 0.06 percent of Si, and the balance of Al.
2. The method according to claim 1, wherein in the step (7), the sawing is to saw the profile into a profile having a length of 4 m.
3. The production method according to claim 1, wherein in the step (8), the medium used for quenching is water.
4. The method according to claim 1, wherein in the step (9), the stretching amount of the profile is controlled to be 1.5-2% during the straightening treatment.
5. The production method according to any one of claims 1 to 4, wherein in the step (1), an Al-Ti-B alloy is used as a refiner; the heating is to heat the mixed material to 750-780 ℃ and keep the temperature for 6-8 h;
in the step (3), the casting molding temperature is 710-730 ℃; the aluminum ingot is cylindrical, and the diameter of the aluminum ingot is 200-300 mm;
in the step (4), the homogenization treatment is to keep the temperature at 460-470 ℃ for 4-24 h;
in the step (6), the heat preservation treatment is to preserve heat for 3 hours at the temperature of 440-470 ℃; the technological parameters in the extrusion forming process are as follows: the temperature of the die is 440-480 ℃, the temperature of the extrusion cylinder is 370-420 ℃, the temperature of the extrusion piece after being taken out of the die is 475-485 ℃, and the extrusion speed is 2-5 m/min; in the extrusion forming process, an alloy with yield strength lower than 90MPa is used as a dummy ingot; the alloy with the yield strength lower than 90MPa is a 1xxx series alloy or a 6xxx series alloy; the 6xxx series alloy is one of 6061, 6063, 6005A and 6082; the 1 xxx-series alloy is one of 1060, 1070; the width of the section obtained after extrusion forming is 75mm, the thickness of the section is 6mm, and the section is L-shaped; and cooling the section bar obtained after extrusion forming by adopting water mist.
6. Use of the aluminium alloy profile produced by the method according to any one of claims 1 to 5 as a raw material in rail transit electrical cabinets.
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