Nickel-based alloy resistant to super-high temperature flame erosion and laser cladding process thereof

Abstract

The application discloses a nickel-based alloy resistant to superhigh-temperature flame corrosion, which comprises the following components in percentage by weight: C<=0.05%, Cr 42-65%, Si 1.0-2.0%, B 1.8-3.0%, and Ni 30-55%. A laser cladding process is also disclosed, wherein the nickel-based alloy powder is used as a cladding material. The nickel-based alloy can be used to prepare a protective coating resistant to superhigh-temperature flame corrosion through the laser cladding process, so as to solve the problems of superhigh-temperature oxidation corrosion and cracking of the cladding layer.

Description

Technical Field

[0001] This invention belongs to the field of laser cladding, and particularly relates to a nickel-based alloy resistant to ultra-high temperature flame erosion and its laser cladding process. Background Technology

[0002] Laser cladding technology has been widely used for surface protection and composition modification of parts to improve their wear resistance, corrosion resistance, oxidation resistance, and other properties. It is an effective means of improving material surface properties. Utilizing the high energy of a laser source, it initiates a complex physicochemical process and rapid solidification process between specific alloy powder and the substrate surface, forming a dense metallurgical coating. During laser cladding, the coating material and trace amounts of the base material melt, resulting in a unique process of rapid melting, metallurgical reaction, and solidification. Laser cladding demonstrates unique advantages in high-temperature oxidation resistance, high-temperature corrosion resistance, and high-temperature wear resistance.

[0003] Currently, the powders used for laser cladding technology mainly include iron-based stainless steel, cobalt-based alloys, and nickel-based alloys. However, the main limitations of existing materials are as follows: (1) The phase transition temperature of the cladding layer is low, and the service life is low in ultra-high temperature environments such as above 1280℃; (2) The high temperature corrosion resistance and excessive oxidation elements make the laser cladding layer prone to cracking. Summary of the Invention

[0004] To address the aforementioned technical problems, this invention provides a nickel-based alloy resistant to ultra-high temperature flame erosion. Using this nickel-based alloy and a laser cladding process, a protective coating resistant to ultra-high temperature flame erosion can be prepared, thus solving the problems of ultra-high temperature oxidation corrosion and cracking of the cladding layer.

[0005] The specific solution of this invention is as follows:

[0006] One of the objectives of this invention is to provide a nickel-based alloy resistant to ultra-high temperature flame erosion, comprising the following components by weight percentage: C≤0.05%, Cr42-65%, Si1.0-2.0%, B1.8-3.0%, Ni30-55%.

[0007] Preferably, the mixture further comprises, by weight percentage: 0.1-0.5% Nb.

[0008] Preferably, the composition comprises the following components by weight percentage: C ≤ 0.05%, Cr 42-65%, Si 1.0-2.0%, B 1.8-3.0%, Nb 0.1-0.5%, with the balance being Ni and unavoidable impurities.

[0009] Preferably, the composition comprises the following components by weight percentage: C < 0.05%, Cr 50-65%, Si 1.2-1.6%, B 2.3-2.5%, Nb 0.1-0.5%, with the balance being Ni and unavoidable impurities.

[0010] Preferably, the unavoidable impurity is Fe. More preferably, Fe < 0.6%.

[0011] This invention, through the design of its components and content, enables the cladding layer obtained by cladding with this nickel-based alloy powder to resist ultra-high temperature flame erosion and avoid cracking. The specific functions of each component are as follows:

[0012] (1) When the Cr content is 42-65%, Cr and Ni form an alloy structure with a solidus temperature higher than 1350℃. When 42%≤Cr<50%, the structure changes from α+γ phase to γ ​​phase. The phase transformation will occur above 700℃, and the phase transformation temperature is much lower than 1288℃ (the application temperature of the material of this invention). Therefore, when used in a high-temperature environment, the phase transformation will reduce its oxidation resistance, and the application temperature should not exceed 1100℃. When 50%≤Cr≤65%, the phase transformation temperature increases to 1300℃, and the oxidation resistance and ablation resistance under ultra-high temperature conditions are greatly improved.

[0013] (2) Increasing the Cr content is beneficial to improving the high-temperature corrosion resistance of the cladding layer, but it also leads to problems such as easy cracking of the laser cladding layer, poor toughness of the cladding layer causing it to peel off during repeated heating and cooling, and poor cladding layer forming performance. In particular, when the Cr content is within the range of this invention and C > 0.05%, chromium carbide is easily formed during laser cladding, leading to cracking of the cladding layer; in order to avoid cracking caused by high Cr content and improve the crack resistance of nickel-based alloys, it is necessary to control C ≤ 0.05%.

[0014] (3) Adding Si and B to the nickel-based alloy system at the same time, the two work together to act as fluxing agents, deoxidizers and slags, which is beneficial to the formation of the cladding layer and to reduce porosity.

[0015] (4) In this invention, Ni can not only form an alloy phase with Cr, but also increase the wettability of the coating, improve the wetting angle of the cladding layer, and improve the smoothness and brightness of the cladding layer surface.

[0016] In a preferred embodiment, adding a certain amount of Nb to the nickel-based alloy can further enhance the oxidation resistance of the cladding layer and achieve a higher operating temperature.

[0017] The second objective of this invention is to provide a laser cladding process, using any of the above-mentioned nickel-based alloy powders resistant to ultra-high temperature flame erosion as the cladding material.

[0018] Preferably, laser cladding is performed under a protective atmosphere, which is a mixture of argon and hydrogen.

[0019] Preferably, the protective atmosphere comprises 95-99 wt% argon, with the balance being hydrogen. More preferably, the protective atmosphere comprises 98 wt% argon and 2 wt% hydrogen.

[0020] When using the nickel-based alloy powder described in this invention for laser cladding, a mixture of argon and hydrogen is used. Hydrogen can prevent chromium oxide doping caused by Cr during laser cladding, which can lead to cracking of the cladding layer.

[0021] Preferably, during laser cladding, the laser power is 1500-1600W, the laser head is a circular spot, and the spot diameter is ≤0.2mm. If the laser power is too low, the cladding layer will not melt sufficiently and the bonding strength with the substrate will be low; if the power is too high, the cladding layer will not form properly.

[0022] Preferably, the particle size of the nickel-based alloy powder is 53-150 μm. The preparation method of the nickel-based alloy powder is not limited, and includes, but is not limited to, atomization.

[0023] The beneficial effects of this invention are:

[0024] This invention provides a nickel-based alloy with a simple composition and fewer alloying elements, which helps to reduce the difficulty of smelting. While ensuring its resistance to ultra-high temperature, it avoids the problem of cracking during laser cladding caused by high Cr content. Under the laser cladding process, an ultra-high temperature flame erosion cladding layer with uniform composition distribution, no cracks, and no macroscopic pores is obtained. Attached Figure Description

[0025] Figure 1 The images are of pipe fittings used at ultra-high temperature (1288℃) until scrap, wherein: (1) and (3) are images of the cast pipe fittings prepared in Comparative Example 4 used at 1288℃ for 45 days; (2) is an image of the pipe fittings prepared in Example 1 used at 1288℃ for 90 days;

[0026] Figure 2 A photograph of the pipe fitting prepared for Comparative Example 1 after 30 days of use at 1288℃.

[0027] Figure 3 A photograph of the pipe fitting prepared for Comparative Example 2 after 40 days of use at 1288°C. Detailed Implementation

[0028] The technical solution of the present invention will be described in detail below through specific embodiments. However, it should be clearly stated that these embodiments are for illustrative purposes only and are not intended to limit the scope of the present invention.

[0029] Example 1

[0030] A nickel-based alloy resistant to ultra-high temperature flame erosion comprises the following components by weight percentage: C < 0.03%, Cr 55%, Si 1.3%, Fe < 0.6%, B 2.3%, Nb 0.15%, with the balance being Ni.

[0031] The ultra-high temperature cladding layer is prepared on the surface of the pipe using the nickel-based alloy powder described in this embodiment. The laser cladding process specifically includes:

[0032] (1) Remove rust and oil from the surface of the pipe fittings; dry the nickel-based alloy powder for later use; the particle size of the nickel-based alloy powder is 53-150μm;

[0033] (2) Under the protection of mixed gas, a circular spot laser head is used to perform cladding treatment on the above-treated pipe to obtain a cladding layer with a thickness of 1.5 mm; wherein, the spot diameter is 0.2 mm, the laser power is 1550 W, and the mixed gas is 98% Ar + 2% H2.

[0034] The cladding layer prepared in this embodiment is free of cracks and macroscopic pores, and its composition is uniformly distributed. The laser-clad pipes had a service life of up to 90 days in a coal-fired furnace at 1288℃ before being scrapped. The reason for the scrapping was deformation caused by prolonged exposure to high temperatures, but the laser cladding layer on its surface remained intact. Figure 1 As shown in (2).

[0035] Example 2

[0036] A nickel-based alloy resistant to ultra-high temperature flame erosion comprises the following components by weight percentage: C < 0.05%, Cr 53%, Si 1.4%, Fe < 0.6%, B 2.6%, Nb 0.3%, with the balance being Ni.

[0037] The ultra-high temperature cladding layer is prepared on the surface of the pipe using the nickel-based alloy powder described in this embodiment. The laser cladding process specifically includes:

[0038] (1) Remove rust and oil from the surface of the pipe fittings; dry the nickel-based alloy powder for later use; the particle size of the nickel-based alloy powder is 53-150μm;

[0039] (2) Under the protection of mixed gas, a circular spot laser head is used to perform cladding treatment on the above-treated pipe to obtain a cladding layer with a thickness of 1.3 mm; wherein, the spot diameter is 0.2 mm, the laser power is 1600 W, and the mixed atmosphere is 98% Ar + 2% H2.

[0040] The cladding layer prepared in this embodiment is free of cracks and macroscopic pores, and its composition is uniformly distributed. The laser-clad pipes have a service life of up to 90 days in a coal-fired furnace at 1288℃ before being scrapped. The reason for the scrapping is deformation caused by prolonged exposure to high temperatures, but the laser cladding layer on its surface remains intact at this point.

[0041] Example 3

[0042] A nickel-based alloy resistant to ultra-high temperature flame erosion comprises the following components by weight percentage: C < 0.03%, Cr 43%, Si 1.3%, Fe < 0.6%, B 2.3%, Nb 0.15%, and Ni balance.

[0043] The ultra-high temperature cladding layer is prepared on the surface of the pipe using the nickel-based alloy powder described in this embodiment. The laser cladding process specifically includes:

[0044] (1) Remove rust and oil from the surface of the pipe fittings; dry the nickel-based alloy powder for later use; the particle size of the nickel-based alloy powder is 53-150μm;

[0045] (2) Under the protection of mixed gas, a circular spot laser head is used to perform cladding treatment on the above-treated pipe to obtain a cladding layer with a thickness of 1.4 mm; wherein, the spot diameter is 0.2 mm, the laser power is 1580 W, and the mixed atmosphere is 98% Ar + 2% H2.

[0046] The cladding layer prepared in this embodiment is free of cracks and macroscopic pores, and the composition of the cladding layer is uniformly distributed. The service life of the laser-clad pipe in a coal-fired furnace at 1288℃ is 50 days before the pipe is scrapped. During use, the laser cladding layer on its surface gradually shows uniform ablation.

[0047] Example 4

[0048] A nickel-based alloy resistant to ultra-high temperature flame erosion comprises the following components by weight percentage: C < 0.03%, Cr 55%, Si 1.3%, Fe < 0.6%, B 2.3%, with the balance being Ni.

[0049] The nickel-based alloy powder described in this embodiment is used to prepare an ultra-high temperature resistant cladding layer on the surface of the pipe fitting. The cladding process steps and other parameters are the same as in Example 1, and a cladding layer with a thickness of 1.5 mm is obtained.

[0050] The cladding layer prepared in this embodiment is free of cracks and macroscopic pores, and its composition is uniformly distributed. The pipes treated with laser cladding had a service life of 60 days in a coal-fired furnace at 1288℃ before becoming unusable. The reason for the unusable pipes was that the laser cladding layer was uniformly ablated, thinning and leading to failure.

[0051] Comparative Example 1

[0052] The commercially available high-temperature alloy C276 has the following chemical composition by weight percentage: C 0.1%, Cr 15.0%, Si 0.5%, Fe≤6.0%, Mo 16.0%, Co 1.0%, Mn≤1.0%, W 4.0%, with the balance being Ni.

[0053] A cladding layer was prepared on the surface of the pipe fitting using the high-temperature alloy C276 described in the comparative example. The cladding process steps and other parameters were the same as in Example 1, and a cladding layer with a thickness of 1.5 mm was obtained.

[0054] The cladding layer prepared in this comparative example is free of cracks and macroscopic pores, and the composition of the cladding layer is uniformly distributed. The laser cladding layer on the outer surface of the pipe prepared in this comparative example was almost completely ablated after 30 days of use in a coal-fired furnace at 1288℃. The ablation was particularly pronounced at the overlaps between the laser cladding layers. Figure 2 As shown.

[0055] Comparative Example 2

[0056] A nickel-based alloy comprising, by weight percentage: C < 0.05%, Cr 68%, Si 1.4%, Fe < 0.6%, B 2.6%, Nb 0.3%, with the balance being Ni.

[0057] The nickel-based alloy described in this comparative example was used to prepare a cladding layer on the surface of the pipe fitting. The cladding process and other parameters were the same as in Example 2. The cladding layer prepared in this comparative example cracked severely. During use in a coal-fired furnace at 1288°C, oxidation occurred at the cracked areas, leading to bulging and delamination. Figure 3 As shown, the service life is 40 days. It is evident that an increase in Cr content exceeding the range of 42-65% leads to cracking of the cladding layer.

[0058] Comparative Example 3

[0059] A cobalt-based superalloy comprises the following components by weight percentage: C 1.8%, Cr 29.0%, Si 0.5%, Mo 9.0%, Fe≤3.0%, Mn 0.5%, Ni≤3.0%, and Co balance.

[0060] The cobalt-based superalloy described in this comparative example was used to prepare a cladding layer on the surface of the pipe fitting. The cladding process steps and other parameters were the same as in Example 3.

[0061] The cladding layer prepared in this comparative example is free of cracks and macroscopic pores, and the composition of the cladding layer is uniformly distributed. The laser-clad pipe was used in a coal-fired furnace at 1288℃ for 35 days. The surface was ablated to a depth of 15mm into the substrate, and the pipe wall thickness was reduced to the point of being scrapped. The 1.4mm thick cladding layer was completely ablated.

[0062] Comparative Example 4

[0063] Using traditional manufacturing processes, namely centrifugal casting of stainless steel pipes, the outer surface of the pipe fittings is coated with casting sand as a protective layer against high-temperature oxidation. In an operating environment of 1288℃, after 45 days of high-temperature erosion, the sand layer on the outer surface of the cast pipe gradually burns away, and the pipe fittings are uniformly eroded, resulting in a continuous thinning of the wall thickness and ultimately rendering them unusable. Figure 1 The pipe fittings (1) and (3) are shown in the figure.

[0064] The above description is only a preferred embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any equivalent substitutions or modifications made by those skilled in the art within the scope of the technology disclosed in the present invention, based on the technical solution and inventive concept of the present invention, should be covered within the scope of protection of the present invention.

Claims

1. A laser cladding process, characterized in that, Laser cladding is performed using nickel-based alloy powder resistant to ultra-high temperature flame erosion as the cladding material under a protective atmosphere; the protective atmosphere is a mixture of argon and hydrogen. The nickel-based alloy powder resistant to ultra-high temperature flame erosion comprises the following components by weight percentage: C < 0.05%, Cr 50-65%, Si 1.0-2.0%, B 1.8-3.0%, Nb 0.1-0.5%, with the balance being Ni and unavoidable impurities.

2. The laser cladding process according to claim 1, characterized in that, The protective atmosphere comprises 95-99 wt% argon and the balance being hydrogen; preferably, the protective atmosphere is 98 wt% argon and 2 wt% hydrogen.

3. The laser cladding process according to claim 1 or 2, characterized in that, During laser cladding, the laser power is 1500-1600W, the laser head is a circular spot, and the spot diameter is ≤0.2mm.

4. The laser cladding process according to claim 1 or 2, characterized in that, The particle size of the nickel-based alloy powder is 53-150 μm.

5. The laser cladding process according to claim 1, characterized in that, The composition by weight percentage is as follows: C < 0.05%, Cr 50-65%, Si 1.2-1.6%, B 2.3-2.5%, Nb 0.1-0.5%, with the balance being Ni and unavoidable impurities.

6. The laser cladding process according to claim 1, characterized in that, The unavoidable impurity is Fe; Fe < 0.6%.

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