A high-corrosion-resistant Fe-Cr-Mo-W-Y amorphous laser cladding powder material for marine equipment protection and a coating preparation method thereof

Abstract

This invention relates to the field of marine engineering materials and surface engineering technology, specifically to a method for preparing Fe-based multi-element alloy powder with amorphous structure forming capability and laser cladding surface strengthening coating materials. The powder's chemical composition, by mass percentage, includes: Cr: 17%–21%, Mo: 15%–19%, W: 10%–15%, Y: 2%–4%, C: 2%–4%, B: 1%–2%, with the balance being Fe. Compared to traditional Fe-based cladding materials, this invention, by introducing elements such as W and Y and optimizing the proportions of the multi-element system, makes the coating more prone to exhibiting a predominantly amorphous structure under rapid laser solidification conditions, and demonstrates stable corrosion resistance and hardness levels in seawater corrosive environments. The powder system and cladding process of this invention can achieve effective surface protection for key components of marine engineering equipment, exhibiting good engineering applicability and application prospects.

Description

Technical Field

[0001] This invention relates to the field of marine engineering materials and surface engineering technology, specifically to the preparation method of Fe-based multi-element alloy powder with amorphous structure forming capability and laser cladding surface strengthening coating material, which is suitable for surface protection applications of marine engineering equipment in chloride-containing corrosion and abrasion environments. Background Technology

[0002] Marine engineering equipment is often exposed to corrosive environments containing chloride ions during long-term service, such as seawater, humid salt spray, and high humidity environments, which can trigger failure modes such as pitting corrosion, crevice corrosion, and localized corrosion. The chloride ion content in seawater in typical sea areas is generally high, making structures such as pump and valve components, sealing surfaces, flange connection areas, and shaft components prone to corrosion pits, grooves, or localized thinning, thereby affecting the overall structural stability and service life.

[0003] Existing surface strengthening materials for marine engineering equipment mainly include Ni-based weld overlay materials, Fe-based wear-resistant weld overlay materials, and some thermal spray coating systems. While Ni-based weld overlay materials exhibit good corrosion resistance, they are costly and may still experience localized corrosion in high chloride ion environments. Fe-based weld overlay materials are often primarily reinforced with crystalline carbides, and their microstructure may increase their susceptibility to localized corrosion in seawater. Although thermal spray coatings possess high hardness, their bonding primarily relies on mechanical interlocking, resulting in limited density. Under long-term service, they are prone to media penetration and localized peeling, making it difficult to meet the stability requirements of marine engineering equipment for surface protection.

[0004] Amorphous alloys, due to their absence of grain boundaries and uniform microstructure, are considered to have certain application potential in corrosion resistance. However, most publicly available Fe-based amorphous powders are geared towards general wear-resistant or general laser cladding applications, with compositional categories concentrated in the Fe-Cr-Mo-BC system. Research on compositional systems specifically for marine high-chloride ion corrosion environments is relatively insufficient. For marine high-chloride ion environments, the synergistic design of existing Fe-based amorphous powder systems incorporating elements such as W to improve pitting corrosion stability and rare earth element purification is still relatively inadequate. Furthermore, there is still room for improvement in the amorphous structural stability of existing powder systems under rapid solidification conditions during laser cladding.

[0005] Therefore, it is necessary to develop a Fe-based amorphous laser cladding powder material suitable for the chlorine-containing corrosive environment of marine engineering. By optimizing the synergistic effect of elements such as Cr, Mo, W and rare earth Y, the cladding coating can exhibit an amorphous structure during rapid solidification, thereby improving its stability in the seawater corrosive environment and providing more reliable surface protection for key components of marine engineering equipment. Summary of the Invention

[0006] This invention addresses the existing technical problems of pitting corrosion, crevice corrosion, and localized corrosion that easily occur in key components of marine engineering equipment in high-chloride seawater environments. It proposes a Fe-Cr-Mo-WY multi-element iron-based cladding powder with amorphous structure formation capability suitable for laser cladding processes, and its coating preparation method. By optimizing the content of corrosion-resistant elements such as Cr, Mo, and W, and introducing an appropriate amount of rare earth element Y to improve the purity of the molten pool, the cladding coating exhibits a dense microstructure dominated by an amorphous structure during rapid laser solidification. This enhances the surface stability of the coating in chloride-containing corrosive media and reduces the susceptibility to localized corrosion.

[0007] To achieve the above objectives, the present invention employs the following technical solution: A highly corrosion-resistant Fe-Cr-Mo-WY amorphous laser cladding powder material for the protection of marine engineering equipment, wherein the powder chemical composition by mass percentage includes: Cr: 17%–21%, Mo: 15%–19%, W: 10%–15%, Y: 2%–4%, C: 2%–4%, B: 1%–2%, with the balance being Fe.

[0008] The powder is prepared by gas atomization, with high particle sphericity and good flowability. The particle size is preferably 20-75μm to meet the requirements of stable powder feeding and uniform forming during laser cladding.

[0009] In the composition system of this invention, chromium (Cr) is the main corrosion-resistant element, with its content controlled at 17-21%, used to enhance the coating's resistance to pitting corrosion. Molybdenum (Mo) content is set at 15-19%, which synergistically improves corrosion resistance with Cr and helps suppress crystallization tendencies under rapid solidification conditions. Tungsten (W) content is controlled at 10-15%, used to enhance the coating's localized corrosion stability and structural robustness. The rare earth element yttrium (Y) is added in the range of 2-4%, used to improve the purity of the molten pool and promote microstructure homogenization. Carbon (C) and boron (B), as typical amorphous forming elements, are controlled at 2%-4% and 1%-2% respectively, which is beneficial for obtaining a predominantly amorphous structure under laser rapid solidification conditions.

[0010] Through the synergistic design of the aforementioned elements, this invention constructs a combination of a Cr-Mo-W corrosion-resistant system and a CB amorphous formation system, enabling the powder material to possess both amorphous formation capability and corrosion resistance. Compared with existing Fe-Cr-Mo-BC system powders, the material of this invention is more suitable for chloride-ion-containing marine environments and has stronger application specificity in terms of structural stability and corrosion resistance.

[0011] A method for preparing a coating of highly corrosion-resistant Fe-Cr-Mo-WY amorphous laser cladding powder material for the protection of marine engineering equipment includes: using a fiber laser as a heat source to prepare a Fe-based amorphous structure characteristic coating through a coaxial annular powder feeding high-speed laser cladding process; cleaning and pre-treating the processing surface before cladding to ensure a reliable metallurgical bonding interface between the cladding layer and the substrate; and using a circular laser spot with a diameter set within the range of 2–4 mm during processing to obtain a uniform and stable molten pool morphology. The laser power is set within the range of 3–6 kW, the scanning speed is 10–25 m / min, and the powder feed rate is 15–30 g / min. By adjusting the laser power, scanning speed, and spot size, the energy input per unit area is controlled within a range suitable for rapid solidification, resulting in a coating with a predominantly amorphous structure. During the cladding process, both the powder carrier gas and the protective gas are inert gases. The powder carrier gas flow rate is set to 8–12 L / min, and the protective gas flow rate is set to 10–15 L / min, ensuring that the protective gas flow rate is higher than the powder carrier gas flow rate. This ensures that the powder beam enters the molten pool stably and prevents powder from falling into the nozzle. For multi-pass cladding, the overlap rate is set to 35%–55%, which can form a continuous and dense cladding channel.

[0012] The Fe-Cr-Mo-WY amorphous alloy coating prepared using the process of this invention exhibits a dense and uniform microstructure, forming a stable metallurgical bonding interface with the substrate. The coating's microhardness can range from 800 to 1100 HV. 0.2 Within a certain range, the hardness variation along the thickness direction is stable, the surface morphology remains intact in chloride-containing corrosive media, the degree of localized corrosion is low, and the overall corrosion resistance is stable. Reasonable control of energy input can obtain a uniform cladding structure dominated by amorphous structure, meeting the requirements of corrosion resistance and hardness in marine engineering service environments.

[0013] The descriptions of amorphous structures in this invention are based on microstructural characteristics under laser rapid solidification conditions and are not limited by a specific amorphous phase content. The powder system of this invention possesses both good laser cladding formability and corrosion resistance in marine engineering services, which helps improve the microstructure and performance stability of existing Fe-based cladding materials under seawater corrosion conditions.

[0014] Compared with existing technologies, the beneficial effects of this invention are: Compared to traditional Fe-based cladding materials, this invention, by introducing elements such as W and Y and optimizing the proportions of the multi-component system, makes the coating more prone to exhibiting a predominantly amorphous structure under rapid laser solidification conditions. It also demonstrates stable corrosion resistance and hardness in seawater corrosive environments. Under simulated seawater immersion conditions (3.5 wt.% NaCl solution), the corrosion rate of the coating can reach approximately 0.01–0.05 mm / a. This invention's powder system and cladding process can achieve effective surface protection for key components of marine engineering equipment, exhibiting good engineering applicability and application prospects. Attached Figure Description

[0015] Figure 1 These are XRD characterization images of the cladding layer from Example 1. Figure 2 These are XRD characterization images of the cladding layer from Example 2. Figure 3 These are XRD characterization images of the cladding layer in Example 3. Detailed Implementation

[0016] The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the embodiments of the present invention. Obviously, the described embodiments are merely illustrative and are not intended to limit the present invention. The process parameters in this embodiment are representative parameter points selected within the stated range. Those skilled in the art can adjust the parameters within the stated range without affecting the technical effects of the present invention.

[0017] Example 1: The powder system of this invention is used, with a particle size of 20–75 μm. Typical mass percentages are as follows: Cr: 18.3%, Mo: 17.3%, W: 13.7%, Y: 3.4%, C: 3.4%, B: 1.4%, with the balance being Fe.

[0018] A coaxial annular powder feeding laser cladding process was adopted, with a spot diameter of 2.5 mm, a laser power of 5 kW, a scanning speed of 20 m / min, and a powder feeding rate of 25 g / min. The powder feeding carrier gas flow rate was set to 10 L / min, and the protective gas flow rate was set to 14 L / min. The protective gas flow rate was higher than the powder feeding carrier gas flow rate to avoid powder backflow and reduce molten pool oxidation.

[0019] Under the above process parameters, the thickness of a single cladding layer is approximately 0.4 mm, determined by both process heat input and powder capture rate, resulting in a uniform and dense formation. Figure 1 As shown, X-ray diffraction (XRD) analysis revealed that the coating exhibited a spectrum dominated by broad, diffuse peaks, indicating that it is primarily composed of an amorphous phase. The coating's microhardness is approximately 980 HV. 0.2The corrosion rate was measured to be approximately 0.021 mm / a in a 3.5 wt.% NaCl solution, indicating stable overall corrosion resistance.

[0020] Example 2: The powder system of this invention is selected with a particle size of 38–75 μm. Typical mass percentages are as follows: Cr: 19.6%, Mo: 16.4%, W: 10.1%, Y: 2.6%, C: 2.5%, B: 1.2%, balance Fe.

[0021] A coaxial annular powder feeding laser cladding process was adopted, with a spot diameter of 3.0 mm, a laser power of 4 kW, a scanning speed of 18 m / min, and a powder feeding rate of 18 g / min. The powder feeding carrier gas flow rate was set to 9 L / min, and the protective gas flow rate was set to 12 L / min. The protective gas flow rate was higher than the powder feeding carrier gas flow rate to avoid powder backflow and reduce molten pool oxidation.

[0022] Under the above process parameters, the thickness of a single cladding layer is approximately 0.35 mm, determined by both process heat input and powder capture rate, resulting in good surface formation. Figure 2 As shown, X-ray diffraction (XRD) analysis revealed that the coating exhibited a spectrum dominated by broad, diffuse peaks, indicating that it is primarily composed of an amorphous phase. The coating's microhardness reached 870 HV. 0.2 In the range of 3.5 wt.% NaCl solution, corrosion tests were conducted, and the corrosion rate was measured to be approximately 0.042 mm / a, indicating that the overall corrosion resistance remained stable.

[0023] Example 3: The powder system of this invention is used, with a particle size of 20–53 μm. Typical mass percentages are as follows: Cr: 20.5%, Mo: 18.7%, W: 15%, Y: 2.7%, C: 2.8%, B: 1.8%, balance Fe.

[0024] A coaxial annular powder feeding laser cladding process was adopted, with a spot diameter of 2.8 mm, a laser power of 6 kW, a scanning speed of 20 m / min, and a powder feeding rate of 16 g / min. The powder feeding carrier gas flow rate was set to 11 L / min, and the protective gas flow rate was set to 15 L / min. The protective gas flow rate was higher than the powder feeding carrier gas flow rate to avoid powder backflow and reduce molten pool oxidation.

[0025] Under the above process parameters, the thickness of a single cladding layer is approximately 0.5 mm, resulting in a continuous and dense formation. For example... Figure 3 As shown, X-ray diffraction (XRD) analysis revealed that the coating exhibited a spectrum dominated by broad, diffuse peaks, indicating that it is primarily composed of an amorphous phase. The coating's microhardness reached 1030 HV. 0.2Within the range, corrosion tests were conducted in a 3.5 wt.% NaCl solution, and the corrosion rate was measured to be approximately 0.035 mm / a, indicating stable overall corrosion resistance.

[0026] In summary, the Fe-Cr-Mo-WY multi-element iron-based amorphous alloy powder of this invention, combined with a coaxial annular powder feeding laser cladding process, can form a dense, continuous, and metallurgically bonded cladding coating on the substrate surface. Under rapid solidification conditions, the coating exhibits a predominantly amorphous structure, with a microhardness ranging from 800 to 1100 HV. 0.2 Within the range, the hardness changes smoothly in the thickness direction, with no obvious abrupt change areas.

[0027] In chloride-containing corrosive media, the corrosion rate ranges from 0.01 to 0.05 mm / a, and the overall corrosion resistance is stable, which helps to reduce the development trend of pitting and localized corrosion. The coating has a uniform structure and reliable interfacial bonding, and has good applicability in typical marine engineering service environments.

[0028] The laser cladding process of this invention features low heat input, low dilution rate, and stable forming, enabling the formation of dense coatings without additional heat treatment. It boasts high material utilization and is suitable for surface strengthening of newly manufactured critical components in marine engineering equipment and online repair of in-service components. The powder system and process combination of this invention show promising application prospects in chlorine-containing corrosive and abrasive environments.

[0029] The technical means disclosed in the embodiments of the present invention are not limited to the specific methods described above. Equivalent modifications that can be made by those skilled in the art based on these methods are all within the protection scope of the present invention.

Claims

1. A high corrosion resistant Fe-Cr-Mo-W-Y amorphous laser cladding powder material for protection of marine equipment, characterized in that, Powder chemical composition by mass percentage Includes: Cr: 17%–21%, Mo: 15%–19%, W: 10%–15%, Y: 2%–4%, C: 2%–4%, B: 1%–2%, with the balance being Fe.

2. The high corrosion resistant Fe-Cr-Mo-W-Y amorphous laser cladding powder material for the protection of marine equipment according to claim 1, characterized in that, The powder particle size is 20–75 μm.

3. A method for preparing a coating of a high corrosion resistant Fe-Cr-Mo-W-Y amorphous laser cladding powder material for the protection of marine equipment according to claim 1 or 2, characterized in that, The method includes: using a fiber laser as a heat source to prepare a Fe-based amorphous structure characteristic coating through a coaxial ring-shaped powder feeding laser cladding process; selecting a circular laser spot with a diameter of 2–4 mm; setting the laser power to 3–6 kW, the scanning speed to 10–25 m / min, and the powder feeding rate to 15–30 g / min; during the cladding process, both the powder feeding carrier gas and the protective gas are inert gases, with the powder feeding carrier gas flow rate set to 8–12 L / min and the protective gas flow rate set to 10–15 L / min.

4. The method for preparing a coating of high corrosion resistant Fe-Cr-Mo-W-Y amorphous laser cladding powder material for the protection of marine equipment according to claim 3, characterized in that, The coating microhardness is in the range of 800-1100 HV 0.2 .

5. The method for coating preparation of high corrosion resistant Fe-Cr-Mo-W-Y amorphous laser cladding powder material for marine equipment protection according to claim 3, characterized in that, The surface to be processed is cleaned and pretreated before cladding.

6. The method for preparing a coating of highly corrosion-resistant Fe-Cr-Mo-WY amorphous laser cladding powder material for marine equipment protection according to claim 3, characterized in that, When performing multi-layer cladding, the overlap rate is set between 35% and 55%.

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