Preparation method of heterogeneous bimetal metallurgical composite sleeve for seabed transportation

Abstract

The invention discloses a preparation method of a heterogeneous bimetal metallurgical composite casing pipe for seabed transportation. The preparation method comprises the following steps: S1, pretreatment of a base pipe; s2, material preparation, wherein 80-99.99 wt.% of Ni-based alloy powder and 0.01-20 wt.% of nano ceramic particles are subjected to ball milling to be evenly mixed, and mixed powder is obtained; s3, laser cladding is conducted, specifically, a coaxial powder feeding mode is adopted, and the mixed powder is subjected to laser cladding on the surface of the base tube; and S4, a composite layer is formed, specifically, under the action of a laser heat source, the Ni-based alloy is molten and metallurgically bonded with the base tube, the nano ceramic particles are not molten and are evenly dispersed and distributed in a cladding layer, and the wear-resistant and corrosion-resistant composite layer with the thickness being 0.2-3 mm is formed. Nano-scale ceramic particles and Ni-based alloy powder are compounded, and the nano-scale ceramic particles are uniformly dispersed and distributed in a cladding layer matrix by utilizing the high-temperature stability and non-melting characteristic of the nano-particles in the laser cladding process, so that the wear resistance of the composite layer is remarkably improved, and the material loss in the erosion corrosion process is inhibited.

Description

Technical Field

[0001] The present invention relates to the technical field of composite pipes, in particular to a method for preparing a heterogeneous bimetallic metallurgical composite casing for submarine transportation. Background Art

[0002] Subsea pipeline protection casings are subject to long-term service in high-salinity, high-humidity seawater environments, constantly enduring chemical corrosion, microbial corrosion, and erosion and wear from high-velocity fluids. Currently, mainstream pipe materials face a performance-cost trade-off. While conventional carbon steel pipes (such as Q235 and X65 series) offer good mechanical strength and are inexpensive, their surface corrosion and wear resistance are significantly insufficient. They are susceptible to localized pitting, grooving, and uniform thinning, resulting in generally short casing service life and high maintenance costs due to frequent replacement. On the other hand, while pure Ni-based alloy pipes offer excellent seawater corrosion resistance, the structural strength required in deepwater high-pressure environments requires a significant increase in pipe wall thickness, resulting in a significant increase in Ni-based alloy material consumption and high costs. Furthermore, due to their relatively low hardness, pure Ni-based alloys face the risk of accelerated failure due to erosion and wear in sandy seabed areas, further improving their wear and corrosion resistance is a technical need. Summary of the Invention

[0003] The purpose of the present invention is to overcome the problems of low wear resistance and poor cost performance of existing pure Ni-based alloy casings, and to provide a method for preparing a heterogeneous bimetallic metallurgical composite casing for submarine transportation.

[0004] A method for preparing a heterogeneous bimetallic metallurgical composite casing for submarine transportation comprises the following steps: S1: Base tube pretreatment: Select the base tube, polish the surface to remove the oxide scale, and clean and dry it; S2: Material preparation: 80-99.99 wt.% Ni-based alloy powder and 0.01-20 wt.% nano-ceramic particles are ball-milled until uniformly mixed to obtain a mixed powder; S3: Laser cladding: Using coaxial powder feeding, the mixed powder is laser clad on the substrate surface; the process parameters are: laser power 0.3-12kW, spot size 1-6mm, scanning speed 12-5000mm / min, powder feeding rate 10-120g / min, shielding gas flow rate 5-30L / min; S4: Forming a composite layer: Under the action of the laser heat source, the Ni-based alloy melts and metallurgically combines with the base tube, while the nano-ceramic particles are not melted and evenly dispersed in the cladding layer, forming a wear-resistant and corrosion-resistant composite layer with a thickness of 0.2~3mm.

[0005] Furthermore, the Ni-based alloy composition is 45-70wt.% Ni, 15-30wt.% Cr, 6-12wt.% Mo, 2-6wt.% Nb, 1-5wt.% Fe, 0.2-0.4wt.% Si, 0.2-0.5wt.% Co, and 0.1-0.3wt.% Mn.

[0006] Furthermore, the nano-ceramic particles are selected from one or more of nano-oxides, nano-carbides, and nano-nitrides, and have a particle size of 1 to 1000 nm.

[0007] Furthermore, the nano-oxide is one or more of Al3O2, ZrO2, CeO2, and YSZ, the nano-carbide is one or more of WC, TiC, NbC, VC, and Cr3C2, and the nano-nitride is one or more of c-BN, Si3N4, AlN, and TiN.

[0008] Furthermore, the Ni-based alloy powder is prepared by gas atomization, water atomization or centrifugal atomization, and has a particle size of 20-250 μm; the nano-ceramic particles are prepared by sintering mechanical crushing, sol-gel or gas phase method.

[0009] Furthermore, the cladding layer is placed on the inner hole, outer circle, or inner hole and outer circle of the casing.

[0010] Furthermore, the base pipe is any one of X65QO / L450QO, L245Q(BQ)~L450Q(X65Q), with an inner hole diameter of 0.2~3m and an outer circle diameter of 0.25m~3.5m.

[0011] The beneficial effects of the present invention are: By combining nano-scale ceramic particles with Ni-based alloy powder, and leveraging the nanoparticles' high-temperature stability and unmelted properties during laser cladding, they are uniformly dispersed throughout the cladding layer matrix. The nanoparticles' "pinning effect" effectively refines the cladding layer's grain size and, acting as a hard reinforcement, significantly improves the composite layer's wear resistance and inhibits material loss during erosion-corrosion.

[0012] By optimizing the Ni-based alloy composition, while maintaining the austenitic matrix's resistance to Cl⁻ pitting corrosion, the synergistic effect of Mo and Nb elements enhances resistance to H₂S stress corrosion cracking (SCC). Combined with the precise heat input control of laser cladding, a dense composite layer with a thickness of only 0.2-3 mm can be formed on the substrate surface, reducing the amount of precious Ni-based alloy used. Metallurgical bonding also ensures interface strength and density, preventing the cladding layer from spalling and blocking seawater infiltration pathways.

[0013] Laser cladding technology with a wide process window is suitable for the large-scale production of casings of varying diameters. By adjusting the powder feed rate and spot size, the cladding layer thickness accuracy of ±0.1mm is achieved, eliminating the need for subsequent machining. Furthermore, the rapid heating and cooling characteristics of the laser minimize thermal deformation of the substrate, and the cladding layer forms a flawless metallurgical bond with the substrate, significantly outperforming thermal spraying, electroplating, and mechanical composite processes. BRIEF DESCRIPTION OF THE DRAWINGS

[0014] Figure 1 This is a schematic diagram of coaxial powder feeding for laser cladding; Figure 2 It is a schematic diagram of laser cladding Ni-based nano-ceramic composite layer; Figure 3 (a) is the surface morphology of the base tube material after corrosion. Figure 3 (b) is the surface morphology of the nickel-based alloy cladding layer after corrosion without nano-ceramics. Figure 3 (c) is the surface morphology of the nickel-based alloy cladding layer with nano-ceramics after corrosion; Figure 4 (a) is the wear scar morphology of the base tube material after friction and wear. Figure 4 (b) is the wear scar morphology of the nickel-based alloy cladding layer after friction and wear without nano-ceramics. Figure 4 (c) is the wear scar morphology of the nickel-based alloy cladding layer with nano-ceramics after friction and wear. DETAILED DESCRIPTION

[0015] The following describes the embodiments of the present invention through specific examples. Those skilled in the art can easily understand other advantages and effects of the present invention from the content disclosed in this specification. The present invention can also be implemented or applied through other different specific embodiments. The details in this specification can also be modified or changed based on different viewpoints and applications without departing from the spirit of the present invention. It should be noted that the following embodiments and features in the embodiments can be combined with each other unless they conflict.

[0016] Example 1 like Figures 1 and 2 As shown, a heterogeneous bimetallic metallurgical composite casing for submarine transportation is manufactured by the following steps: Step S1: L245Q (BQ) grade steel pipe is selected as the base pipe, with an inner diameter of 0.2m and an outer diameter of 0.25m. The surface is polished to Sa3 cleanliness, then ultrasonically cleaned with acetone and dried.

[0017] Step S2: 80 wt.% of Ni-based alloy powder prepared by gas atomization (composition: 45 wt.% Ni, 15 wt.% Cr, 6 wt.% Mo, 2 wt.% Nb, 1 wt.% Fe, 0.2 wt.% Si, 0.2 wt.% Co, 0.1 wt.% Mn) and 20 wt.% of WC nanoparticles (particle size 1000 nm) prepared by sintering mechanical crushing were ball-milled and mixed for 6 hours.

[0018] Step S3: coaxial powder feeding laser cladding is adopted, and the parameters are set as follows: laser power 0.3 kW, spot size 1 mm, scanning speed 12 mm / min, powder feeding rate 10 g / min, and argon protection flow rate 5 L / min.

[0019] Step S4: forming a composite layer with a thickness of 0.2 mm on the inner hole surface.

[0020] Example 2 like Figures 1 and 2 As shown, a heterogeneous bimetallic metallurgical composite casing for submarine transportation is manufactured by the following steps: Step S1: Select an X65QO grade steel pipe with an inner diameter of 1.6m and an outer diameter of 1.875m. After the surface is polished with a sand belt, it is cleaned with ethanol and dried with nitrogen.

[0021] Step S2: 90 wt.% water-atomized Ni-based alloy powder (57.5 wt.% Ni, 22.5 wt.% Cr, 9 wt.% Mo, 4 wt.% Nb, 3 wt.% Fe, 0.3 wt.% Si, 0.35 wt.% Co, 0.2 wt.% Mn) and 10 wt.% sol-gel prepared Al2O3 (5 wt.%) + TiC (5 wt.%) mixed nanoparticles (particle size 500 nm) were ball-milled for 4 h.

[0022] Step S3: The laser cladding parameters are: power 6 kW, spot size 3.5 mm, scanning speed 2500 mm / min, powder feeding rate 65 g / min, and nitrogen protection flow rate 17.5 L / min.

[0023] Step S4: Synchronously cladding the inner and outer walls to form a 1.6 mm composite layer.

[0024] Example 3 like Figures 1 and 2 As shown, a heterogeneous bimetallic metallurgical composite casing for submarine transportation is manufactured by the following steps: Step S1: Use L450QO grade steel pipe with an inner diameter of 3m and an outer diameter of 3.5m. After the surface is shot blasted, plasma cleaning is performed.

[0025] Step S2: 99.99 wt.% centrifugally atomized Ni-based alloy powder (70 wt.% Ni, 30 wt.% Cr, 12 wt.% Mo, 6 wt.% Nb, 5 wt.% Fe, 0.4 wt.% Si, 0.5 wt.% Co, 0.3 wt.% Mn) and 0.01 wt.% vapor-phase prepared c-BN nanoparticles (particle size 1 nm) were ball-milled for 2 h.

[0026] Step S3: Set the laser power to 12 kW, the spot size to 6 mm, the scanning speed to 5000 mm / min, the powder feeding rate to 120 g / min, and the helium shielding flow rate to 30 L / min.

[0027] Step S4: forming a 3 mm ultra-thick composite layer on the outer surface.

[0028] The composite casings prepared in Examples 1 to 3 were tested for corrosion resistance and wear resistance according to YB / T 6178-2024: Metallic Materials Wear Test - Pin-on-Disc Friction Wear Method. The test results are shown in Table 1. Table 1: Performance test results of various embodiments

[0029] As shown in Table 1, this solution combines nano-sized ceramic particles with Ni-based alloy powder, leveraging the nanoparticles' high-temperature stability and unmelted properties during laser cladding to uniformly disperse them within the cladding layer matrix. The nanoparticles act as nucleation sites, increasing the nucleation rate and effectively refining the cladding layer's grain size. Furthermore, as a hard reinforcement phase, they significantly improve the composite layer's wear resistance and inhibit material loss during erosion-corrosion.

[0030] The following is a further explanation of this plan: Comparative Example 1 (base tube) Select ordinary carbon steel pipe, specifically X65QO grade steel pipe; Comparative Example 2 (Nickel-based alloy cladding layer without nano-ceramics) This comparative example is the same as Example 2, except that only 100 wt.% Ni-based alloy powder (composition is the same as that in Example 2) is used, and no ceramic particles are added; The above comparative examples 1 and 2 were subjected to wear resistance and corrosion resistance tests, and the results were analyzed as follows: corrosion resistance tests were conducted on the base tube, the nickel-based alloy cladding layer without nano-ceramics, and the nickel-based alloy cladding layer with nano-ceramics to compare their corrosion resistance: Figure 3 As shown, Figure 3 (a) is the surface morphology of the base tube material after corrosion. Figure 3 (b) is the surface morphology of the nickel-based alloy cladding layer after corrosion without nano-ceramics. Figure 3(c) is the surface morphology of the nickel-based alloy cladding layer with nano-ceramics after corrosion; the data shows that the average corrosion rate of the substrate is 0.3213 mm / a, and the maximum pitting rate is 0.5128 mm / a; the average corrosion rate of the nickel-based alloy cladding layer without nano-ceramics is 0.0115 mm / a, and the maximum pitting rate is 0.0201 mm / a; the average corrosion rate of the nickel-based alloy cladding layer with nano-ceramics is 0.0109 mm / a, and the maximum pitting rate is 0.0223 mm / a, indicating that the corrosion resistance of this heterogeneous bimetallic metallurgical composite pipe is significantly improved compared with the substrate.

[0031] The wear resistance test was carried out on the base tube, the nickel-based alloy cladding layer without nano-ceramics, and the nickel-based alloy cladding layer with nano-ceramics to compare their wear resistance: Figure 4 As shown, Figure 4 (a) is the wear scar morphology of the base tube material after friction and wear. Figure 4 (b) is the wear scar morphology of the nickel-based alloy cladding layer after friction and wear without nano-ceramics. Figure 4 (c) shows the wear scar morphology of the nickel-based alloy cladding layer after friction and wear. Data show that the wear scar of the nickel-based alloy cladding layer with nanoceramics is significantly smaller in width and depth than that of the substrate and the nickel-based alloy cladding layer without nanoceramics. The volume loss after friction and wear on the substrate is 180.597 mm³, the volume loss of the nickel-based alloy cladding layer without nanoceramics is 130.496 mm³, and the volume loss of the nickel-based alloy cladding layer with nanoceramics is 5.553 mm³. This indicates that the wear resistance of the Ni-based nanoceramic composite layer is significantly improved compared to the base tube.

[0032] In this scheme, nanoparticles form stable interfacial adsorption due to their high surface energy, hindering grain boundary migration through the Zener pinning effect and refining the grains of the cladding layer; laser energy is preferentially absorbed by the Ni-based alloy, and ceramic particles remain solid in the molten pool due to their low thermal conductivity, avoiding the formation of brittle carbides; nanoceramic particles that fall off during wear form a third-body lubricating film at the friction interface.

[0033] The process of this solution is further described below. Example 3 is selected as a comparative example. When the laser power exceeds the upper limit, analysis is performed as follows: Comparative Example 3 (Laser power exceeds upper limit) Step changes: S3: laser power 18 kW (far exceeding the upper limit of 12 kW in the claim), other parameters are the same as Example 3; S2: mixed powder composition is the same as Example 3 (0.01 wt.% c-BN).

[0034] Conclusion: Excessive laser power leads to an excessively high dilution rate of the cladding layer, that is, the Fe element content in the cladding layer is too high, the corrosion resistance is seriously insufficient, the heat-affected zone of the base pipe is significantly enlarged, the overall toughness of the pipe is insufficient, and the cladding layer cracks.

[0035] Comparative Example 4 (the proportion of nano-oxide exceeds 20 wt.%) This comparative example is the same as Example 3, except that the ratio of the nano-oxide is 30 wt.%, and the ratio of the Ni-based alloy powder is 70 wt.%. Conclusion: The cladding process is difficult to implement, the cladding layer is very prone to defects such as cracks and pores, and the production efficiency is severely restricted, making it impossible to achieve industrial application.

[0036] The above-described embodiments merely represent specific implementations of the present invention. While the descriptions are relatively specific and detailed, they should not be construed as limiting the scope of the present invention. It should be noted that a person skilled in the art would be able to make numerous variations and improvements without departing from the spirit of the present invention, and all such variations and improvements fall within the scope of protection of the present invention.

Claims

1. A method for preparing a heterogeneous bimetallic metallurgical composite casing for submarine transportation, characterized by: The following steps are involved: S1: Base tube pretreatment: Select the base tube, polish the surface to remove the oxide scale, and clean and dry it; S2: Material preparation: 80-99.99 wt.% Ni-based alloy powder and 0.01-20 wt.% nano-ceramic particles are ball-milled until uniformly mixed to obtain a mixed powder; S3: Laser cladding: Using coaxial powder feeding, the mixed powder is laser clad on the substrate surface; the process parameters are: laser power 0.3-12kW, spot size 1-6mm, scanning speed 12-5000mm / min, powder feeding rate 10-120g / min, shielding gas flow rate 5-30L / min; S4: Forming a composite layer: Under the action of the laser heat source, the Ni-based alloy melts and metallurgically combines with the base tube, while the nano-ceramic particles are not melted and evenly dispersed in the cladding layer, forming a wear-resistant and corrosion-resistant composite layer with a thickness of 0.2~3mm.

2. The method for preparing a heterogeneous bimetallic metallurgical composite casing for submarine transportation according to claim 1, characterized in that: The Ni-based alloy comprises 45-70 wt.% Ni, 15-30 wt.% Cr, 6-12 wt.% Mo, 2-6 wt.% Nb, 1-5 wt.% Fe, 0.2-0.4 wt.% Si, 0.2-0.5 wt.% Co, and 0.1-0.3 wt.% Mn.

3. The method for preparing a heterogeneous bimetallic metallurgical composite casing for submarine transportation according to claim 1, characterized in that: The nano-ceramic particles are selected from one or more of nano-oxides, nano-carbides, and nano-nitrides, and have a particle size of 1 to 1000 nm.

4. The method for preparing a heterogeneous bimetallic metallurgical composite casing for submarine transportation according to claim 3, characterized in that: The nano-oxide is one or more of Al3O2, ZrO2, CeO2, and YSZ; the nano-carbide is one or more of WC, TiC, NbC, VC, and Cr3C2; and the nano-nitride is one or more of c-BN, Si3N4, AlN, and TiN.

5. The method for preparing a heterogeneous bimetallic metallurgical composite casing for submarine transportation according to claim 1, characterized in that: The Ni-based alloy powder is prepared by gas atomization, water atomization or centrifugal atomization, and has a particle size of 20 to 250 μm; the nano-ceramic particles are prepared by sintering mechanical crushing, sol-gel or gas phase method.

6. The method for preparing a heterogeneous bimetallic metallurgical composite casing for submarine transportation according to claim 1, characterized in that: The cladding layer is placed on the inner hole, outer circle or inner hole and outer circle of the casing.

7. The method for preparing a heterogeneous bimetallic metallurgical composite casing for submarine transportation according to claim 1, characterized in that: The base pipe is any one of X65QO / L450QO, L245Q (BQ) ~ L450Q (X65Q), with an inner hole diameter of 0.2~3m and an outer circle diameter of 0.25m~3.5m.

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