Fastener for offshore engineering machinery and preparation process thereof

Abstract

The application discloses a kind of fasteners for ocean engineering machinery and preparation process thereof, belong to the field of ocean engineering machinery parts manufacturing technology.The technical scheme is: including fastener part blank machining and surface pretreatment, fastener part surface modification and post-processing, fastener part surface modification includes the preparation of Cr / C / Fe adhesive layer and ZrVCrNbB working layer on the surface of the part by laser cladding method, wherein the raw material of Cr / C / Fe adhesive layer is Cr, C and Fe powder, the particle diameter of powder is 55-75nm, and the weight percentage is respectively: 25-30%, 15-25% and 45-60%;ZrVCrNbB working layer: ZrVCrNbB composite powder is used.The application can improve the corrosion resistance and wear resistance of the surface of ocean engineering machinery parts, prolong the service life of fastener parts, and reduce the use and maintenance cost of ocean engineering machinery.

Description

Technical Field

[0001] This invention belongs to the field of marine engineering machinery parts manufacturing technology, specifically relating to a fastener for marine engineering machinery and its manufacturing process. Background Technology

[0002] Oceans cover approximately 71% of the Earth's surface, and navigation and the marine industry have become a vital pillar of global economic development, with over 90% of international trade transported by sea. However, due to the high salt concentration (generally around 3.5%), rich oxygen content, and the presence of numerous marine microorganisms and macroorganisms in seawater, coupled with wave impacts and sunlight exposure, corrosion problems are severe for infrastructure and critical industrial facilities operating in the marine environment. This is particularly pronounced in marine engineering machinery, which has become the most significant factor affecting the safety, lifespan, and reliability of ships, near-shore engineering projects, and deep-sea facilities.

[0003] Fasteners are a wide range of mechanical parts used for fastening connections. They are used in a wide range of industries, including energy, electrical appliances, machinery, chemicals, metallurgy, mold making, hydraulics, and more. Various types of fasteners can be found on all kinds of machinery, equipment, ships, vehicles, railways, bridges, buildings, structures, tools, instruments, chemicals, meters, and supplies. They are also the most widely used basic mechanical components in marine engineering machinery.

[0004] With the rapid development of the marine engineering machinery industry, the performance requirements for fasteners used in marine engineering machinery are also becoming increasingly stringent. However, due to the special working conditions of the marine operating environment, the service life of current fasteners can no longer meet the actual needs of use. Therefore, vigorously developing anti-corrosion materials and technologies for marine engineering is of great significance for ensuring the service safety and reliability of marine engineering machinery, reducing the occurrence of major catastrophic accidents, and extending the service life of marine engineering machinery. Chinese invention patent CN114875401A discloses a surface modification method for a high-pressure hydraulic pump gear shaft: after the hydraulic pump gear shaft part blank is quenched, tempered at high temperature, and rough machined, a Mo / C / Fe bonding layer and a Mo2FeB2 / Mo working layer are prepared on the surface of the part using a laser cladding method, followed by stress-relief tempering, semi-finishing, and finishing. However, its surface hardness is only HV1600, and its structure, material composition, and wear rate cannot meet the actual application needs of the modern marine shipbuilding industry. Summary of the Invention

[0005] This invention provides a fastener for marine engineering machinery and its manufacturing process. The process involves preparing a Cr / C / Fe bonding layer and a ZrVCrNbB working layer. The Cr / C / Fe composite bonding layer can mitigate the performance differences between the subsequent working layer and the base material of the fastener part, improving the structural and performance matching between the two. It also increases the bonding performance between the laser cladding layer and the base material, and enhances the impact resistance of the working layer. The ZrVCrNbB cladding layer possesses extremely high hardness, excellent corrosion resistance, chemical stability, and friction and wear resistance, thereby improving the corrosion resistance and wear resistance of the surface of marine engineering machinery parts, extending the service life of the fastener parts, and reducing the use and maintenance costs of marine engineering machinery.

[0006] The technical solution of this invention is as follows:

[0007] Firstly, the manufacturing process of fasteners for marine engineering machinery is disclosed, including machining and surface pretreatment of fastener blanks, surface modification of fastener parts, and post-treatment. Surface modification of fastener parts includes the preparation of a Cr / C / Fe bonding layer and a ZrVCrNbB working layer on the surface of the parts using a laser cladding method.

[0008] (1) Machining of fastener parts: Quenching of fastener part blank → High-temperature tempering → Rough machining;

[0009] (2) Surface pretreatment of fastener parts: Remove oil and oxide film from the surface of the parts, rinse and dry;

[0010] (3) Preparation of Cr / C / Fe bonding layer: The raw materials of Cr / C / Fe bonding layer are Cr, C and Fe powders with a particle diameter of 55-75nm and their weight percentages are 25-30%, 15-25% and 45-60%, respectively. Under argon protection, the laser cladding parameters are adjusted to form a Cr / C / Fe bonding layer with the surface of the fastener parts.

[0011] (4) ZrVCrNbB working layer: ZrVCrNbB composite powder is used. The particle diameter of the ZrVCrNbB composite powder is 80-120nm. The atomic percentage content of each element in the ZrVCrNbB composite powder is: Zr: 50-60at.%, V: 15-20at.%, Cr: 10-12at.%, Nb: 4-8at.%, B: 10-15at.%. Under argon protection, the laser cladding parameters are adjusted so that the ZrVCrNbB composite powder forms a ZrVCrNbB working layer on the surface of the Cr / C / Fe bonding layer.

[0012] (5) Post-processing: After the workpiece cools down, stress-relieving tempering → semi-finishing → finishing.

[0013] Preferably, the base material of the fastener parts is one of medium carbon steel and its alloy steel, such as 40Cr, 35CrMo, and 42CrMo.

[0014] Preferably, the laser cladding parameters for the Cr / C / Fe bonding layer are: argon protective gas with a flow rate of 8L / min-15L / min; and the laser cladding process parameters for the Cr / C / Fe bonding layer are: laser power 1250-1350W, scanning speed 200-235mm / min, laser spot diameter 1.4-2.0mm, overlap rate 50-60%, and cladding thickness 0.8-1.3mm.

[0015] Preferably, the laser cladding parameters for the ZrVCrNbB working layer are: argon protective gas flow rate of 14L / min-18L / min; and the laser cladding process parameters for the ZrVCrNbB working layer are: laser power of 1850-2350W, scanning speed of 225-255mm / min, laser spot diameter of 2.0-2.6mm, overlap rate of 42-50%, and cladding thickness of 2.0-3.0mm.

[0016] Preferably, the Cr, C and Fe powders are ground and mixed in a ball mill for 160-180 minutes.

[0017] Preferably, the ZrVCrNbB composite powder is ground and mixed in a ball mill for 240-300 minutes.

[0018] Secondly, marine fasteners prepared using the aforementioned preparation process are disclosed.

[0019] Compared with the prior art, the present invention has the following advantages:

[0020] 1. The Cr / C / Fe composite adhesive layer of the present invention can mitigate the performance differences between the subsequent working layer and the substrate material of the fastener parts, improve the structural and performance matching performance between the two, and increase the bonding performance between the laser cladding layer / substrate material and the impact resistance of the working layer;

[0021] 2. In the ZrVCrNbB boride working layer, Zr acts as a solid solution strengthener, improving the coating's strength, wear resistance, and chemical stability. V enhances the working layer's wear resistance and corrosion resistance, while Cr acts as a solid solution strengthener, improving its oxidation resistance and corrosion resistance. Nb increases the working layer's hardness, strength, compressive strength, wear resistance, and corrosion resistance. The ZrVCrNbB cladding layer possesses extremely high hardness, excellent corrosion resistance, chemical stability, and friction and wear resistance. It can improve the corrosion resistance and wear resistance of marine engineering machinery parts, achieving a surface hardness of over HV2400, which is four times the hardness of traditional surface carburizing heat treatment (HV650). Corrosion resistance is increased by more than five times, extending the service life of fasteners used in marine engineering machinery by more than four times, and reducing the wear rate by 70-82%.

[0022] 3. The fasteners for marine engineering machinery and their manufacturing process of the present invention can improve the adhesion performance of fastener parts, and the effective coating process time is only 2-4% of that of the traditional carburizing process, reducing the maintenance and upkeep costs of fasteners by 65-73%. Attached Figure Description

[0023] Figure 1 This is a schematic diagram of the surface structure of the fastener part for marine engineering machinery prepared according to Embodiment 1 of the present invention. In the figure, 1 is the ZrVCrNbB working layer; 2 is the Cr / C / Fe bonding layer; and 3 is the fastener part substrate.

[0024] Figure 2 This is the surface optical morphology of the fastener part prepared in Embodiment 1 of the present invention.

[0025] Figure 3 This is a comparison chart of the average wear rate of the fastener parts prepared in Embodiment 1 of the present invention and traditional carburized parts. Detailed Implementation

[0026] Example 1

[0027] This embodiment provides a manufacturing process for fasteners used in marine engineering machinery. The fastener base material is 42CrMo medium-carbon alloy steel. After quenching, high-temperature tempering, and rough machining, a Cr / C / Fe bonding layer and a ZrVCrNbB working layer are prepared on the surface of the fastener part using a laser cladding method. Then, stress-relief tempering, semi-finishing, and finishing are performed. Specifically, the process includes the following steps:

[0028] (1) Machining of fastener parts: Fastener part base blank → Quenching (915℃, oil cooling) → High temperature tempering (620℃, holding time: 160min; cooling method: air cooling) → Rough machining (surface roughness Ra25μm, machining size: tolerance lower limit -1.5mm).

[0029] (2) Surface pretreatment of fastener parts: Remove oil and oxide film from the surface of the parts, rinse and dry;

[0030] (3) Preparation of Cr / C / Fe composite powder: Cr, C and Fe composite powder is used, with a particle diameter of 70 nm and a weight percentage of 30%, 25% and 45%, respectively. The Cr / C / Fe powder is ground and mixed in a ball mill for 175 min.

[0031] (4) Preparation of ZrVCrNbB composite powder: ZrVCrNbB composite powder, wherein the particle diameter of the ZrVCrNbB composite powder is 120nm, and the atomic percentage content of each element in the ZrVCrNbB composite powder is: Zr: 55at.%, V: 15at.%, Cr: 12at.%, Nb: 8at.%, B: 10at.%, and the powder is ground and mixed in a ball mill for 300min.

[0032] (5) Cr / C / Fe bonding layer: Argon protective gas is introduced at a flow rate of 14L / min; Cr / C / Fe bonding layer is laser cladding, and the cladding process parameters are: laser power 1350W, scanning speed 230mm / min, laser spot diameter 2.0mm, overlap rate 60%, and cladding thickness 1.2mm.

[0033] (6) Clad ZrVCrNbB working layer: Argon protective gas is introduced at a flow rate of 17L / min; laser cladding of ZrVCrNbB working layer, the cladding process parameters are: laser power 2300W, scanning speed 250mm / min, laser spot diameter 2.5mm, overlap rate 50%, cladding thickness 2.9mm.

[0034] (7) Post-processing: After the fastener workpiece has cooled down, stress-relieving tempering (515℃, air cooling) is performed → semi-finishing is performed in the machining center (surface roughness Ra3.2μm, machining allowance 0.3mm) → finish machining is performed in the machining center (surface roughness Ra1.6μm, machining dimensions within tolerance range).

[0035] like Figure 1 The fastener part obtained in this embodiment has the following structure: from the inside to the outside, the fastener part substrate 1 has a Cr / C / Fe bonding layer 2 and a ZrVCrNbB working layer 3.

[0036] The surface morphology of the laser-clad ZrVCrNbB coated fasteners obtained in this embodiment is as follows: Figure 2As shown, the microhardness of the coating surface reaches HV2520 (testing equipment: HVS-1000A micro Vickers hardness tester, load 2.0N), which is nearly 4 times the surface hardness of the traditional carburizing process (HV625-670). Under the same friction test conditions (HRT-A02 ball-and-disc friction and wear tester, reciprocating linear motion, grinding balls are WC balls with a surface hardness of HRC80-90, load 100N, friction speed 10mm / s, test time 30min), the wear rate of the laser-clad ZrVCrNbB layer prepared by this method is only 2.24×10⁻⁶. -6 mm 3 The wear rate of parts treated with this method is reduced by 78.4% compared to traditional carburizing processes, as shown in Figure 3. Furthermore, the effective coating process time is only about 2 hours, which is only 2-4% of the time required for traditional carburizing. In addition, fastener parts prepared by this method show virtually no corrosion after 15 months of use and can be disassembled normally, reducing maintenance and upkeep costs for marine engineering machinery fasteners by 70%. In contrast, fastener parts prepared by traditional heat treatment processes show severe corrosion and oxidation after only 7 months of use, and may even become impossible to disassemble, affecting the normal operation and maintenance of marine engineering machinery.

[0037] Example 2

[0038] This embodiment provides a surface modification method for fasteners used in marine engineering machinery. The fastener substrate material is 35CrMo medium-carbon alloy steel. After quenching, high-temperature tempering, and rough machining, a Cr / C / Fe bonding layer and a ZrVCrNbB working layer are prepared on the surface of the fastener part using a laser cladding method. Then, stress-relief tempering, semi-finishing, and finishing are performed. Specifically, the method includes the following steps:

[0039] (1) Machining of fastener parts: Fastener part base blank → Quenching (890℃, water cooling) → High temperature tempering (600℃, holding time: 200min; cooling method: air cooling) → Rough machining (surface roughness Ra50μm, machining size: tolerance lower limit -1mm).

[0040] (2) Surface pretreatment of fastener parts: Remove oil and oxide film from the surface of the parts, rinse and dry;

[0041] (3) Preparation of Cr / C / Fe composite powder: Cr, C and Fe composite powder is used, with a particle diameter of 55nm and a weight percentage of 25%, 15% and 60%, respectively. The Cr / C / Fe powder is ground and mixed in a ball mill for 160min.

[0042] (4) Preparation of ZrVCrNbB composite powder: ZrVCrNbB composite powder, wherein the particle diameter of the ZrVCrNbB composite powder is 85nm, and the atomic percentage content of each element in the ZrVCrNbB composite powder is: Zr: 55at.%, V: 15at.%, Cr: 12at.%, Nb: 8at.%, B: 10at.%, and the powder is ground and mixed in a ball mill for 240min.

[0043] (5) Cr / C / Fe bonding layer: Argon protective gas is introduced at a flow rate of 8L / min; Cr / C / Fe bonding layer is laser cladding, and the cladding process parameters are: laser power 1250W, scanning speed 200mm / min, laser spot diameter 1.4mm, overlap rate 50%, and cladding thickness 0.8mm.

[0044] (6) Clad ZrVCrNbB working layer: Argon protective gas is introduced at a flow rate of 14L / min; laser cladding of ZrVCrNbB working layer, the cladding process parameters are: laser power 1850W, scanning speed 225mm / min, laser spot diameter 2.0mm, overlap rate 42%, cladding thickness 2.0mm.

[0045] (7) Post-processing: After the fastener workpiece has cooled down, stress-relieving tempering (525℃, air cooling) is performed → semi-finishing is performed in the machining center (surface roughness Ra3.2μm, machining allowance 0.2mm) → finish machining is performed in the machining center (surface roughness Ra1.6μm, machining dimensions within tolerance range).

[0046] The ZrVCrNbB laser cladding layer prepared in this embodiment achieves a surface microhardness of HV2445, which is more than three times higher than the surface hardness of parts prepared by traditional carburizing processes (HV650). Under the same friction test conditions, the wear rate of the laser cladding ZrVCrNbB layer prepared by this method is 2.24 × 10⁻⁶. -6 mm 3 / N·m, which reduces the wear rate of parts treated by traditional carburizing process by more than 71.4%.

[0047] Although the present invention has been described in detail with reference to the accompanying drawings and preferred embodiments, the invention is not limited thereto. Various equivalent modifications or substitutions can be made to the embodiments of the invention by those skilled in the art without departing from the spirit and essence of the invention, and such modifications or substitutions should all be within the scope of the invention. Any variations or substitutions that can be easily conceived by those skilled in the art within the technical scope disclosed in the invention should also be covered within the protection scope of the invention. Therefore, the protection scope of the invention should be determined by the scope of the claims.

Claims

1. A manufacturing process for fasteners used in marine engineering machinery, comprising machining and surface pretreatment of fastener blanks, surface modification of fastener parts, and post-treatment, characterized in that, The base material of the fastener parts is one of 40Cr, 35CrMo, or 42CrMo carbon alloy steel. Surface modification of the fastener parts includes preparing a Cr / C / Fe bonding layer and a ZrVCrNbB working layer on the part surface using laser cladding. (1) Preparation of Cr / C / Fe bonding layer: The raw materials of Cr / C / Fe bonding layer are Cr, C and Fe powders with a particle diameter of 55-75nm and a weight percentage of 25-30%, 15-25% and 45-60%, respectively. Under argon protection, the laser cladding parameters are adjusted to form Cr / C / Fe bonding layer with the surface of fastener parts. (2) Preparation of ZrVCrNbB working layer: ZrVCrNbB composite powder is used. The particle diameter of the ZrVCrNbB composite powder is 80-120nm. The atomic percentage content of each element in the ZrVCrNbB composite powder is: Zr: 50-60at.%, V: 15-20at.%, Cr: 10-12at.%, Nb: 4-8at.%, B: 10-15at.%. Under argon protection, the laser cladding parameters are adjusted so that the ZrVCrNbB composite powder and the Cr / C / Fe bonding layer surface form a ZrVCrNbB working layer. (3) The laser cladding parameters for the ZrVCrNbB working layer are: argon protective gas is introduced at a flow rate of 14L / min-18L / min; the laser cladding process parameters for the ZrVCrNbB working layer are: laser power 1850-2350W, scanning speed 225-255mm / min, laser spot diameter 2.0-2.6mm, overlap rate 42-50%, and cladding thickness 2.0-3.0mm; The laser cladding parameters for the Cr / C / Fe bonding layer in step (1) are: argon protective gas with a flow rate of 8L / min-15L / min; and the laser cladding process parameters for the Cr / C / Fe bonding layer are: laser power 1250-1350W, scanning speed 200-235mm / min, laser spot diameter 1.4-2.0mm, overlap rate 50-60%, and cladding thickness 0.8-1.3mm. In step (1), during the preparation process of the Cr / C / Fe bonding layer, the Cr, C and Fe powders are ground and mixed in a ball mill for 160-180 min. In step (2), during the ZrVCrNbB working layer preparation process, the ZrVCrNbB composite powder is ground and mixed in a ball mill for 240-300 min.

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