A laser pulse processing method for improving corrosion resistance of cupronickel alloy and cupronickel alloy

Abstract

The application provides a laser pulse processing method for improving corrosion resistance of white copper alloy and the white copper alloy, and relates to the technical field of material engineering. The laser pulse processing method for improving corrosion resistance of white copper alloy comprises the following steps: performing surface cleaning on the white copper alloy, then heating the white copper alloy by using a laser heater, and rapidly cooling the white copper alloy by using a cooling medium. According to the laser pulse processing method, the metal with a thickness of 1-10 microns on the surface of the white copper alloy is rapidly melted under the non-contact heating action of the laser, and then rapidly cooled under the action of low-temperature inert gas, so that an amorphous layer with a thickness of 1-10 microns is formed. The amorphous layer can protect the surface of the alloy and hinder the penetration of ions in the environment on one hand, and the amorphous layer is easy to be passivated to form a dense passivation layer, thereby improving the corrosion resistance of the alloy.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of material engineering, and particularly relates to a laser pulse processing method for improving the corrosion resistance of white copper alloy and white copper alloy. BACKGROUND

[0002] Traditional white copper alloy is copper-nickel alloy, has excellent corrosion resistance, and is one of the most widely used corrosion-resistant metal materials. White copper has better seawater scouring resistance, and is widely used in ships due to its good forming and welding performance and thermal conductivity. Among them, the passivation range of iron white copper BFe10-1-1 and BFe30-1-1 alloy is relatively wide, and the corrosion resistance is good. It is called "marine engineering alloy", and is one of the indispensable materials for condensers in seawater desalination, coastal power stations, ships and the like. However, due to the long-term exposure of white copper to anion environments with strong oxidizing properties such as Cl -1 , O 2- , S 2- , electrochemical corrosion still inevitably occurs. At the same time, the alloy inevitably contains other alloy elements or impurities during the smelting preparation process, which also affects its corrosion resistance. In addition, long-term exposure to seawater, acid and alkaline media and other corrosive environments, the grain boundary of the material is more prone to corrosion than the grain interior, and intergranular corrosion occurs. Therefore, improving the corrosion resistance of white copper alloy is one of the hot scientific and technical problems at home and abroad, and is of great significance to important industrial fields such as seawater purification, ship design and chemical industry.

[0003] Generally speaking, the methods for improving the corrosion resistance of white copper alloy mainly include micro-alloying and surface coating. Among them, micro-alloying refers to adding alloying elements such as Fe, Mn, Zn, Al and rare earth elements to white copper alloy to improve the electrochemical corrosion performance of the alloy or improve the passivation film forming ability of the alloy, so as to improve the corrosion resistance of the alloy. However, the addition of alloying elements cannot fundamentally solve the problem of intergranular corrosion resistance. Surface coating of the alloy can isolate the corrosion of the alloy from the outside (such as patent CN202211483322.7, a method for improving the corrosion resistance of white copper alloy pipe; CN202410202037.6, high-hardness nickel-free electrolytic corrosion-resistant plating layer structure and preparation method thereof), but the bonding performance between the coating and the alloy substrate will affect the corrosion resistance.

[0004] Therefore, the present application provides a laser pulse processing method for improving the corrosion resistance of white copper alloy to solve the technical problem of improving the corrosion resistance of white copper alloy. SUMMARY

[0005] The purpose of the present application is to provide a laser pulse processing method for improving the corrosion resistance of white copper alloy and white copper alloy to solve the above problems.

[0006] To achieve the above object, the application adopts the following technical solutions:

[0007] A laser pulse processing method for improving the corrosion resistance of cupronickel alloy, comprising:

[0008] The surface of the cupronickel alloy is cleaned, then heated by a laser heater, and then rapidly cooled by a cooling medium.

[0009] Preferably, the cupronickel alloy is pre-machined or polished, and the surface roughness is Ra1.6 to Ra0.8.

[0010] Preferably, the surface cleaning uses one or more of mechanical cleaning, acid cleaning, plasma cleaning, and laser surface cleaning. The goal is to remove oil, impurities, or other coverings on the surface of the alloy.

[0011] Preferably, the laser heater includes one or more of a CO2 laser, a Nd:YAG laser, a semiconductor laser, and an excimer laser.

[0012] Preferably, the power of the laser heater is 1-10KW, and the light source of the laser heater is 2-50mm away from the surface of the cupronickel alloy.

[0013] Preferably, when the laser heater is heating, the scanning direction is parallel to the surface of the cupronickel alloy, and the scanning speed is 100-1000mm / min.

[0014] Preferably, the number of scans is 2-10 times.

[0015] Preferably, the cooling medium includes one or more of high-pressure nitrogen, high-pressure helium, liquid nitrogen, and liquid helium.

[0016] Preferably, when the rapid cooling is performed, the cooling speed of the surface of the cupronickel alloy is not less than 1×10 4 ℃ / s;

[0017] After each heating, the number of rapid coolings is not less than 1.

[0018] The application also provides a cupronickel alloy prepared using the laser pulse processing method for improving the corrosion resistance of cupronickel alloy.

[0019] Compared with the prior art, the application has the following beneficial effects:

[0020] The laser pulse processing method for improving the corrosion resistance of cupronickel alloy provided in the application uses a laser to rapidly scan the surface of the cupronickel alloy, and then uses low-temperature inert gas to rapidly blow and scan, so that the metal with a thickness of 1-10 microns on the surface of the cupronickel alloy rapidly melts under the non-contact heating action of the laser, and then rapidly cools under the action of low-temperature inert gas, forming an amorphous layer with a thickness of 1-10 microns. This amorphous layer has the same chemical composition as the substrate, but the atoms in it are in a disordered and random distribution state, and do not have the grain boundaries of traditional crystal materials, nor do they contain dislocations, grain boundaries, twins, vacancies, and crystallographic defects such as stacking faults. Therefore, this amorphous layer does not have the difference in position of the intracrystalline grain boundary, on the one hand, it can protect the surface of the alloy and hinder the penetration of ions in the environment, thereby improving its intergranular corrosion resistance; on the other hand, the amorphous layer is easy to passivate and form a dense passivation layer, thereby improving the corrosion resistance of the alloy. This method can significantly improve the corrosion resistance of the alloy without changing the chemical composition, and has the same chemical composition as the substrate, without affecting the performance and use of the material substrate.

[0021] This method has strong applicability to cupronickel alloy pipes, plates or other surfaces of various shapes, thicknesses and specifications.

[0022] The cupronickel alloy provided in the application is prepared by the above method, which fundamentally solves the problem of intergranular corrosion resistance and has excellent corrosion resistance. In a 3.5% NaCl solution, the corrosion rate at room temperature can be reduced by at least 30%, and the surface hardness can be increased by at least 50%. BRIEF DESCRIPTION OF DRAWINGS

[0023] In order to more clearly illustrate the technical solutions of the embodiments of the application, the following will briefly introduce the drawings needed to be used in the embodiments. It should be understood that the following drawings only show some embodiments of the application, and therefore should not be regarded as limiting the scope of the application.

[0024] Figure 1 The flowchart of the laser pulse processing method for improving the corrosion resistance of cupronickel alloy provided for the embodiments;

[0025] Figure 2 The schematic diagram of the laser heating;

[0026] Figure 3 The longitudinal section boundary EBSD photo of the B10 cupronickel alloy after laser surface treatment obtained in Example 1;

[0027] Figure 4 The longitudinal section boundary EBSD photo of the cupronickel alloy obtained in Comparative Example 1;

[0028] Figure 5 The longitudinal section boundary EBSD photo of the cupronickel alloy obtained in Comparative Example 2. DETAILED DESCRIPTION

[0029] The embodiments of the present application will be described in detail below in conjunction with specific examples, but it will be understood by those skilled in the art that the following examples are merely illustrative of the present application and should not be considered as limiting the scope of the present application. In the examples, if specific conditions are not specified, the conditions are carried out according to conventional conditions or manufacturer recommendations. The reagents or instruments used are not specified by the manufacturer and are conventional products that can be purchased commercially.

[0030] Example 1

[0031] like Figure 1 As shown, this embodiment provides a laser pulse processing method for improving the corrosion resistance of B10 white copper sheet, which specifically includes the following steps:

[0032] (1) Surface cleaning of white copper alloy

[0033] The surface roughness of the B10 white copper alloy sheet after machining or polishing reaches Ra1.6.

[0034] Mechanical polishing is used to remove oil, impurities or other coverings on the alloy surface.

[0035] (2) Laser heating

[0036] like Figure 2 As shown, a CO2 laser heater with a power of 2.0KW is used to quickly scan the cupronickel within a range of 2-3mm from its surface at a scanning speed of 100mm / min, and the number of repetitions is 2 times.

[0037] (3) Inert gas rapid cooling

[0038] Nitrogen was used to rapidly cool the surface of the copper-nickel alloy after laser heating, and the cooling rate of the copper-nickel alloy surface reached 1×10 4 ℃ / s, cooling once after each laser heating.

[0039] (4) Performance testing

[0040] like Figure 3 As shown, a 2 μm thick amorphous layer is formed on the surface of the white copper alloy.

[0041] In 3.5% NaCl solution, the corrosion rate without treatment is 0.012g / m 2 h, after treatment it is reduced to 0.007g / m 2 h, the corrosion rate at room temperature can be reduced by 41.6%.

[0042] The surface hardness increased from HV118 to HV210, an increase of 78%.

[0043] Example 2

[0044] The embodiment provides a laser pulse processing method for improving the corrosion resistance of B10 cupronickel plate, and specifically comprises the following steps.

[0045] (1) Cleaning the surface of the cupronickel alloy

[0046] After the machining or polishing treatment, the surface roughness of the B10 cupronickel alloy plate reaches Ra0.8.

[0047] The oil stains, impurities or other coverings on the surface of the alloy are removed by mechanical polishing.

[0048] (2) Laser heating

[0049] A CO2 laser heater with a power of 10.0 KW is used to heat the surface of the cupronickel alloy at a distance of 45-50 mm, and the surface is rapidly scanned at a speed of 1000 mm / min, and the scanning is repeated 4 times.

[0050] (3) Inert gas rapid cooling

[0051] Nitrogen is used to rapidly cool the surface of the cupronickel alloy after laser heating, so that the cooling speed of the surface of the cupronickel alloy reaches 2x10 4 ℃ / s, and the cooling is performed 4 times after each laser heating.

[0052] (4) Performance detection

[0053] A 6 μm thick amorphous layer is formed on the surface of the cupronickel alloy.

[0054] In a 3.5% NaCl solution, the corrosion rate of the untreated cupronickel alloy is 0.012 g / m 2 h, and the corrosion rate of the treated cupronickel alloy is reduced to 0.006 g / m 2 h, and the corrosion rate at room temperature is reduced by 50.0%.

[0055] The surface hardness is increased from HV120 to HV221, and the increase is 84.1%.

[0056] Example 3

[0057] The embodiment provides a laser pulse processing method for improving the corrosion resistance of B10 cupronickel pipe, and specifically comprises the following steps.

[0058] (1) Cleaning the surface of the cupronickel alloy

[0059] After the machining or polishing treatment, the surface roughness of the B10 cupronickel alloy pipe reaches Ra0.8.

[0060] The oil stains, impurities or other coverings on the surface of the alloy are removed by cleaning with alcohol and acetone.

[0061] (2) Laser heating

[0062] A CO2 laser heater with a power of 4.0 KW is used to heat the surface of the cupronickel alloy at a distance of 10-15 mm from the surface. The surface is scanned at a speed of 600 mm / min, and the process is repeated 4 times.

[0063] (3) Inert gas rapid cooling

[0064] Nitrogen gas is used to rapidly cool the surface of the cupronickel alloy after laser heating, so that the cooling speed of the surface of the cupronickel alloy reaches 1 x 10 4 / s. After each laser heating, the surface is cooled 4 times.

[0065] (4) Performance testing

[0066] A 3 μm thick amorphous layer is formed on the surface of the cupronickel alloy.

[0067] In a 3.5% NaCl solution, the corrosion rate of the untreated surface is 0.014 g / m 2 h, and after treatment, it is reduced to 0.008 g / m 2 h, and the corrosion resistance at room temperature is reduced by 42.8%.

[0068] The surface hardness is increased from HV115 to HV206, an increase of 79.1%.

[0069] Example 4

[0070] The present embodiment provides a laser pulse treatment method for improving the corrosion resistance of B30 cupronickel plate, which specifically comprises the following steps:

[0071] (1) Surface cleaning of cupronickel alloy

[0072] After machining or polishing treatment, the surface roughness of the B30 cupronickel alloy plate reaches Ra0.8.

[0073] Alcohol + acetone is used for cleaning to remove oil stains, impurities or other coverings on the surface of the alloy.

[0074] (2) Laser heating

[0075] A CO2 laser heater with a power of 4.0 KW is used to heat the surface of the cupronickel alloy at a distance of 10-15 mm from the surface. The surface is scanned at a speed of 600 mm / min, and the process is repeated 4 times.

[0076] (3) Inert gas rapid cooling

[0077] Nitrogen gas is used to rapidly cool the surface of the cupronickel alloy after laser heating, so that the cooling speed of the surface of the cupronickel alloy reaches 1 x 10 4℃ / s, cooling 3 times after each laser heating.

[0078] (4) Performance testing

[0079] A 2 μm thick amorphous layer was formed on the surface of the white copper alloy.

[0080] In 3.5% NaCl solution, the corrosion rate without treatment is 0.013 g / m 2 h, after treatment it is reduced to 0.007 g / m 2 h, the corrosion rate at room temperature can be reduced by 46.1%.

[0081] The surface hardness increased from HV110 to HV203, an increase of 84.5%.

[0082] Comparative Example 1

[0083] Different from Example 1, a conventional heating method (conventional resistance heating, maximum temperature 800°C, holding temperature 30min) was used to heat the cupronickel alloy and then air-cool it (cooling rate was approximately 80-100°C / min). The microstructure of the grains at the surface is shown in the following figure. Figure 4 As shown. Compared with Example 1 ( Figure 3 ) Compared with the sample that was rapidly heated and cooled by laser, the surface of the cupronickel alloy heated by conventional heating method did not have an amorphous layer and only contained ordinary grains.

[0084] The experiment was conducted by using the method of ordinary heating + rapid cooling. It was found that the grain microstructure of the surface of the white copper alloy was different from that of the Figure 4 Similarly, no amorphous layer appears.

[0085] Comparative Example 2

[0086] The copper-nickel alloy was heated by the same laser heating method as in Example 1. The difference from Example 1 was that it was cooled by air cooling (cooling rate was about 80-100℃ / min). The microstructure of the grains at the surface is shown in the following figure. Figure 5 As shown. With the example ( Figure 3 ) Compared with the sample that was rapidly heated and cooled by laser, the surface of the cupronickel alloy cooled by air cooling showed some fine grains but did not contain an amorphous layer.

[0087] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present application, rather than to limit them. Although the present application has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or make equivalent replacements for some or all of the technical features therein. These modifications or replacements do not deviate the essence of the corresponding technical solutions from the scope of the technical solutions of the embodiments of the present application.

Claims

1. A laser pulse treatment method for improving the corrosion resistance of white copper alloy, characterized in that: include: The surface of the white copper alloy is cleaned, then heated by a laser heater, and then rapidly cooled by a cooling medium; The laser heater includes one or more of a CO2 laser, a Nd:YAG laser, a semiconductor laser and an excimer laser; The power of the laser heater is 1-10KW, and the light source of the laser heater is 2-50mm away from the surface of the cupronickel alloy; When the laser heater performs the heating, the scanning direction is parallel to the surface of the cupronickel alloy, and the scanning speed is 100-1000 mm / min; The number of scans is 2-10 times; During the rapid cooling, the cooling rate of the surface of the white copper alloy is not less than 1×10 4 ℃ / s; After each heating, the rapid cooling is performed at least once.

2. The laser pulse processing method for improving the corrosion resistance of white copper alloy according to claim 1, characterized in that: The white copper alloy is pre-machined or polished, and the surface roughness is Ra1.6 to Ra0.

8.

3. The laser pulse processing method for improving the corrosion resistance of white copper alloy according to claim 1, characterized in that: The surface cleaning adopts one or more of mechanical cleaning, acid cleaning, plasma cleaning and laser surface cleaning.

4. The laser pulse processing method for improving the corrosion resistance of white copper alloy according to claim 1, characterized in that: The cooling medium includes one or more of high-pressure nitrogen, high-pressure helium, liquid nitrogen and liquid helium.

5. A white copper alloy, characterized in that: The invention is prepared by using the laser pulse treatment method for improving the corrosion resistance of white copper alloy according to any one of claims 1 to 4.

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