CN115747683A - Method for improving intergranular corrosion resistance of aluminum alloy - Google Patents
Method for improving intergranular corrosion resistance of aluminum alloy Download PDFInfo
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- CN115747683A CN115747683A CN202211180234.XA CN202211180234A CN115747683A CN 115747683 A CN115747683 A CN 115747683A CN 202211180234 A CN202211180234 A CN 202211180234A CN 115747683 A CN115747683 A CN 115747683A
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Abstract
The invention discloses a method for improving intergranular corrosion resistance of aluminum alloy, which is characterized in that an ultrasonic rolling technology is utilized to process the surface layer of the aluminum alloy, so that the second phase structure AlFeSi phase in the aluminum alloy generates chain breakage and thinning phenomena, and the intergranular corrosion resistance of the aluminum alloy is improved. The invention utilizes the ultrasonic rolling technology to obtain the 6061 surface layer with excellent intercrystalline corrosion resistance under the control of reasonable pressure and pass, and effectively solves the problems that the aluminum alloy cracks along the crystal corrosion and is not beneficial to the use of 6-series aluminum alloy as a bearing structure. Through tests, after the material is processed by an ultrasonic rolling technology, the surface roughness of the material is greatly reduced, and the AlFeSi of the second phase structure on the surface layer within the depth of 300 mu m is fractured and refined, so that the extending path of grain boundary corrosion is blocked. The intergranular corrosion attack depth was analyzed to decrease to 80% to 50% of the untreated sample over the same time period. The result shows that compared with an untreated sample, the intergranular corrosion resistance of the material can be improved by 20-50%, and the effect is obvious.
Description
Technical Field
The invention relates to a method for improving the intergranular corrosion resistance of aluminum alloy, belonging to the technical field of aluminum alloy material manufacture.
Background
The 6061 aluminum-magnesium-silicon alloy has excellent processing performance, high toughness, good corrosion resistance and the like, and is widely applied to various industrial structural members which require certain strength and high corrosion resistance, such as tower buildings, railway vehicles, aerospace and the like. However, in terms of corrosion performance, si which is locally excessive during the smelting process is easily combined with Fe element which is difficult to be removed in the molten pool to form needle-shaped intermetallic compound AlFeSi and precipitate at the grain boundary position, thereby forming Intergranular corrosion (IGC). According to the principle of galvanic corrosion, the potential of elements such as Fe, si and the like on a galvanic series is higher than that of Al, so that an AlFeSi phase is represented as a cathode phase in the alloy, the harmful phase is protected by the cathode and greatly accelerates the anodic dissolution of a matrix around the phase, and the bonding force of a grain boundary is weakened, so that the intergranular corrosion cracking of the aluminum alloy is caused, and the use of the 6-series aluminum alloy as a bearing structure is not facilitated. Therefore, a process method is needed to enhance the intergranular corrosion resistance of 6061 aluminum alloy.
Disclosure of Invention
Technical problem to be solved
Aiming at the defects of the prior art, the invention provides a method for improving the intergranular corrosion resistance of the aluminum alloy, so that the 6061 aluminum alloy has the advantage of greatly improving the intergranular corrosion resistance, and the problems that the aluminum alloy cracks along the crystal corrosion and is not beneficial to the use of 6-series aluminum alloy as a bearing structure are solved.
(II) technical scheme
In order to achieve the purpose, the invention provides the following technical scheme: a method for improving the intergranular corrosion resistance of aluminum alloy is characterized in that an ultrasonic rolling technology is utilized to process the surface layer of the aluminum alloy, so that the second phase structure AlFeSi phase in the aluminum alloy generates chain breakage and thinning phenomena, and the intergranular corrosion resistance of the aluminum alloy is improved.
As a preferable scheme for improving the intergranular corrosion resistance of the aluminum alloy, the invention comprises the following steps: the technological parameters of the ultrasonic rolling are as follows: the air pressure is 0.08-0.12 MPa, the rotating speed of the lathe is 90-110r/min, the feeding amount is 0.1-0.12mm/r, and the rolling passes are 1-24 times.
As a preferable scheme for improving the intergranular corrosion resistance of the aluminum alloy, the method comprises the following steps: the technological parameters of the ultrasonic rolling are as follows: the air pressure is 0.10MPa, the lathe rotating speed is 100r/min, the feeding amount is 0.11mm/r, and the rolling pass is 17 times.
As a preferable scheme for improving the intergranular corrosion resistance of the aluminum alloy, the invention comprises the following steps: and before ultrasonic rolling, carrying out surface polishing treatment on the aluminum alloy material.
As a preferable scheme for improving the intergranular corrosion resistance of the aluminum alloy, the method comprises the following steps: immediately ultrasonically cleaning lubricating oil on the surface of the aluminum alloy by using acetone after ultrasonic rolling treatment, then cleaning the aluminum alloy in absolute ethyl alcohol for a short time, and drying the aluminum alloy in cold air.
As a preferable scheme for improving the intergranular corrosion resistance of the aluminum alloy, the method comprises the following steps: the aluminum alloy is 6061 aluminum alloy.
As a preferable scheme for improving the intergranular corrosion resistance of the aluminum alloy, the method comprises the following steps: the aluminum alloy is in a T6 state.
As a preferable scheme for improving the intergranular corrosion resistance of the aluminum alloy, the method comprises the following steps: the aluminum alloy material is in a round bar shape.
(III) advantageous effects
The method for improving the intercrystalline corrosion resistance of the aluminum alloy utilizes the ultrasonic rolling technology to obtain the 6061 surface layer with excellent intercrystalline corrosion resistance under the control of reasonable pressure and pass, and effectively solves the problems that the intercrystalline corrosion cracking of the aluminum alloy is caused and the 6-series aluminum alloy is not beneficial to being used as a bearing structure. Through tests, after the material is processed by an ultrasonic rolling technology, the surface roughness of the material is greatly reduced, and the AlFeSi of the second phase structure on the surface layer within the depth of 300 mu m is fractured and refined, so that the extending path of grain boundary corrosion is blocked. The intergranular corrosion attack depth was analyzed to decrease to 80% to 50% of the untreated sample over the same time period. The result shows that compared with the untreated sample, the intergranular corrosion resistance of the material can be improved by 20-50%, and the effect is obvious.
Drawings
FIG. 1 is an inter-granular corrosion cross section back scattering electron image under different ultrasonic rolling pressures in the invention;
FIG. 2 is a statistical graph of intergranular corrosion depth and width under different ultrasonic rolling pressures;
FIG. 3 is a surface corrosion topography of samples treated with different ultrasonic rolling pressures after the inter-crystal corrosion experiment of the present invention is completed;
FIG. 4 is a schematic diagram of the corrosion mechanism of 6061 aluminum alloy in the invention: (a) an untreated sample; (b) ultrasonically rolling the sample.
Detailed Description
In order to make the aforementioned objects, features and advantages of the present invention comprehensible, embodiments accompanied with figures are described in detail below. In the following description, numerous specific details are set forth in order to provide a thorough understanding of the present invention. This invention may, however, be embodied in many different forms and should not be construed as limited to the embodiments set forth herein, but rather should be construed as broadly as the present invention is capable of modification in various respects, all without departing from the spirit and scope of the present invention.
Example 1
The treatment steps are as follows:
1) Processing a 6061 aluminum alloy sample in an original T6 state into a round rod-shaped sample with the size of phi 22mm multiplied by 130 mm;
2) Grinding a 6061 aluminum alloy round rod sample to 2000 meshes from 400 meshes step by using sand paper;
3) The method comprises the following steps of mounting a 6061 aluminum alloy round bar sample on ultrasonic surface rolling equipment, wherein the ultrasonic surface rolling equipment comprises HKUSM30S Hooke energy metal surface machining control equipment and a CK6140 Computer Numerical Control (CNC) lathe, and carrying out ultrasonic impact rolling treatment on the round bar sample, wherein the specific machining parameters are as follows: the air pressure is 0.08MPa, the lathe rotating speed is 90r/min, the feeding amount is 0.1mm/r, and the rolling pass is 5 times.
4) After ultrasonic surface rolling treatment, the lubricating oil on the surface of the 6061 aluminum alloy round bar is immediately cleaned by acetone ultrasonic, then cleaned in absolute ethyl alcohol for a short time and dried in cold air.
Example 2
The treatment steps are as follows:
1) Processing a 6061 aluminum alloy sample in an original T6 state into a round rod-shaped sample with the size of phi 22mm multiplied by 130 mm;
2) Grinding a 6061 aluminum alloy round rod sample to 2000 meshes from 400 meshes by using sand paper;
3) The method comprises the following steps of installing a 6061 aluminum alloy round bar sample on ultrasonic surface rolling equipment, wherein the ultrasonic surface rolling equipment comprises HKUSM30S Hooke energy metal surface processing control equipment and a CK6140 Computer Numerical Control (CNC) lathe, and performing ultrasonic impact rolling treatment on the round bar sample, wherein the specific processing parameters are as follows: the air pressure is 0.1MPa, the lathe rotating speed is 100r/min, the feeding amount is 0.11mm/r, and the rolling pass is 17 times.
4) After ultrasonic surface rolling treatment, the lubricating oil on the surface of the 6061 aluminum alloy round bar is immediately cleaned by acetone ultrasonic, then cleaned in absolute ethyl alcohol for a short time and dried in cold air.
Example 3
The treatment steps are as follows:
1) Processing a 6061 aluminum alloy sample in an original T6 state into a round rod-shaped sample with the size of phi 22mm multiplied by 130 mm;
2) Grinding a 6061 aluminum alloy round rod sample to 2000 meshes from 400 meshes by using sand paper;
3) The method comprises the following steps of mounting a 6061 aluminum alloy round bar sample on ultrasonic surface rolling equipment, wherein the ultrasonic surface rolling equipment comprises HKUSM30S Hooke energy metal surface machining control equipment and a CK6140 Computer Numerical Control (CNC) lathe, and carrying out ultrasonic impact rolling treatment on the round bar sample, wherein the specific machining parameters are as follows: the air pressure is 0.12MPa, the lathe rotating speed is 110r/min, the feeding amount is 0.12mm/r, and the rolling pass is 24 times.
4) After ultrasonic surface rolling treatment, the lubricant on the surface of the 6061 aluminum alloy round bar is immediately cleaned by acetone ultrasonic cleaning, then cleaned in absolute ethyl alcohol for a short time and dried in cold air.
Comparative example:
the processing steps are as follows:
1) Processing a 6061 aluminum alloy sample in an original T6 state into a round rod-shaped sample with the size of phi 22mm multiplied by 130 mm;
2) The 6061 aluminum alloy round rod sample is gradually polished to 2000 meshes from 400 meshes by using sand paper. The treatment process was the same as in steps 1) and 2) of example 1.
Intergranular corrosion test:
the intergranular corrosion test was carried out according to the aviation industry Standard HB 5255-83. From the samples subjected to the surface ultrasonic rolling treatment in examples 1 to 3, cubic pieces having a length of 6mm, a width of 6mm and a height of 4mm with a curved surface were cut out on the surface thereof, and from the rod-shaped samples subjected to the surface ultrasonic rolling treatment in comparative example, samples having a size of 6mm × 6mm × 4mm were cut out as initial samples. Samples for each parameter were prepared in 3 replicates. Before the intergranular corrosion test, the sample faces except the study surface were covered with epoxy. Degreasing in absolute ethyl alcohol solution, soaking in 10% NaOH solution for 5min, removing oxide film on the surface of the aluminum alloy, and cleaning with distilled water. Soaking in 30% HNO3 solution for 2min to "shine", cleaning in distilled water, and drying. Finally, the cells were soaked in acidified NaCl solution (30 g of NaCl and 10ml of HCl in 1L of distilled water) for 24h. The volume of the solution was adjusted according to the surface area of the sample so that the ratio of the surface of the sample to the volume of the solution was constant at 1cm 2. After the experiment is finished, the test specimen is washed by distilled water, washed by absolute ethyl alcohol and dried by dry cold air, needs to be stored in vacuum and is prepared for subsequent tests. The corrosion morphology and the corrosion depth of the samples were evaluated by confocal laser microscopy, and then the cross sections of the different samples were observed by scanning electron microscopy to evaluate the corrosion depth.
FIG. 1 shows intergranular corrosion data of the examples, and FIG. 1 (a) is an initial sample, in which severe corrosion occurs in an acidified sodium chloride solution, and the corrosion type is shifted from intergranular corrosion to exfoliation corrosion. FIG. 1 (b) shows the results of example 1, which shows that the corrosion of the aluminum alloy surface is reduced, and the exfoliation of the surface is remarkably reduced. When the experimental parameters were set to example 3, the extent of intergranular corrosion damage was minimal (as in fig. 1 d), which failed to break through the deformed layer along the path of the crystallographic corrosion. It has also been found that when the corrosion path extends through the deformable layer, it is evident that a certain degree of broadening of the corrosion path occurs. Whereas in example 2 the etch path through the undeformed region (fig. 1 c) leaves a narrower etch path. This phenomenon indicates that the corrosion medium is retained for a long time while passing through the grain boundaries of the deformation layer, and the longer the retention time is, the wider the corrosion path along the crystal is (fig. 2).
After the intergranular corrosion experiment in fig. 3 is finished, the surface corrosion topography maps of different samples: (a) an untreated sample; (b) example 1; (c) example 2; (d) example 3. In FIG. 3 (a), the surface of the untreated sample was uneven, and it was found from the maximum height and depth range values indicated by the color of the sample that the destruction of the matrix was severe, the area of the etch pit was large, and the etch path extended depth was long. After ultrasonic rolling treatment, the area of the corrosion pit is gradually reduced along with the increase of static pressure and pass, and the damage degree to the matrix is obviously reduced. The erosion path shown in fig. 4 is blocked and the erosion medium stagnates to make the path gradually narrow and wide. After the etch extension path exceeds the deformation region, the intergranular etch path is narrowed from a wide width. But the propagation speed along intergranular corrosion is faster, and intergranular corrosion cracking is more easily caused. The ultrasonic rolling is shown to greatly improve the intergranular corrosion resistance of the 6061 aluminum alloy.
As can be seen from the tests, after the ultrasonic rolling technology is used for processing, the surface roughness of the material is greatly reduced, the second-phase structure AlFeSi on the surface layer within the depth of 300 mu m is fractured and refined, so that the extending path of grain boundary corrosion is blocked, and the intergranular corrosion erosion depth is reduced to 80-50% of that of an unprocessed sample within the same time. The result shows that compared with the untreated sample, the intergranular corrosion resistance of the material can be improved by 20-50%, and the effect is obvious.
The above-mentioned embodiments only express several embodiments of the present invention, and the description thereof is specific and detailed, but not to be understood as limiting the scope of the present invention. It should be noted that, for a person skilled in the art, several variations and modifications can be made without departing from the inventive concept, which falls within the scope of the present invention. Therefore, the protection scope of the present patent should be subject to the appended claims.
Claims (8)
1. A method for improving the intergranular corrosion resistance of aluminum alloy is characterized by comprising the following steps: the surface layer of the aluminum alloy is processed by utilizing an ultrasonic rolling technology, so that the second phase structure AlFeSi phase in the aluminum alloy generates chain scission and thinning phenomena, and the improvement of the intergranular corrosion resistance of the aluminum alloy is realized.
2. The method of improving the resistance of an aluminum alloy to intergranular corrosion according to claim 1, wherein: the technological parameters of the ultrasonic rolling are as follows: the air pressure is 0.08-0.12 MPa, the rotating speed of the lathe is 90-110r/min, the feeding amount is 0.1-0.12mm/r, and the rolling passes are 1-24 times.
3. The method of improving the resistance of an aluminum alloy to intergranular corrosion according to claim 2, wherein: the technological parameters of the ultrasonic rolling are as follows: the air pressure is 0.10MPa, the lathe rotating speed is 100r/min, the feeding amount is 0.11mm/r, and the rolling pass is 17 times.
4. The method for improving the intergranular corrosion resistance of an aluminum alloy according to claim 1, wherein: and before ultrasonic rolling, carrying out surface polishing treatment on the aluminum alloy material.
5. The method of improving the resistance of an aluminum alloy to intergranular corrosion according to claim 1, wherein: immediately ultrasonically cleaning lubricating oil on the surface of the aluminum alloy by using acetone after ultrasonic rolling treatment, then cleaning the aluminum alloy in absolute ethyl alcohol for a short time, and drying the aluminum alloy in cold air.
6. The method of improving the resistance of an aluminum alloy to intergranular corrosion according to claim 1, wherein: the aluminum alloy is 6061 aluminum alloy.
7. The method of improving the resistance of an aluminum alloy to intergranular corrosion according to claim 6, wherein: the aluminum alloy is in a T6 state.
8. The method for improving the intergranular corrosion resistance of an aluminum alloy according to claim 1, wherein: the aluminum alloy material is in a round bar shape.
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| CN101220405A (en) * | 2007-10-10 | 2008-07-16 | 天津大学 | Ultrasonic surface rolling process nanoparticlization method and apparatus |
| CN107400887A (en) * | 2017-08-11 | 2017-11-28 | 江苏大学 | A kind of method that ultrasonic burnishing strengthens laser cladding layer |
| CN112708832A (en) * | 2020-12-17 | 2021-04-27 | 贵州电网有限责任公司 | Surface modification method for improving corrosion resistance of aluminum alloy |
| CN114147236A (en) * | 2021-11-30 | 2022-03-08 | 大连海事大学 | Method for manufacturing stainless steel through ultrasonic rolling and strengthening laser additive |
| CN114182076A (en) * | 2021-12-10 | 2022-03-15 | 北京理工大学 | Ultrasonic rolling surface residual stress regulation and control method by prefabricating surface processing texture |
| CN114770029A (en) * | 2022-04-25 | 2022-07-22 | 贵州电网有限责任公司 | Surface modification method for improving stress corrosion resistance of 7075-T6 aluminum alloy |
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- 2022-09-27 CN CN202211180234.XA patent/CN115747683A/en active Pending
Patent Citations (6)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN101220405A (en) * | 2007-10-10 | 2008-07-16 | 天津大学 | Ultrasonic surface rolling process nanoparticlization method and apparatus |
| CN107400887A (en) * | 2017-08-11 | 2017-11-28 | 江苏大学 | A kind of method that ultrasonic burnishing strengthens laser cladding layer |
| CN112708832A (en) * | 2020-12-17 | 2021-04-27 | 贵州电网有限责任公司 | Surface modification method for improving corrosion resistance of aluminum alloy |
| CN114147236A (en) * | 2021-11-30 | 2022-03-08 | 大连海事大学 | Method for manufacturing stainless steel through ultrasonic rolling and strengthening laser additive |
| CN114182076A (en) * | 2021-12-10 | 2022-03-15 | 北京理工大学 | Ultrasonic rolling surface residual stress regulation and control method by prefabricating surface processing texture |
| CN114770029A (en) * | 2022-04-25 | 2022-07-22 | 贵州电网有限责任公司 | Surface modification method for improving stress corrosion resistance of 7075-T6 aluminum alloy |
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