A method to improve the service life of hydraulic motors in marine vessels

Abstract

This invention discloses a method for improving the service life of hydraulic motors for marine vessels, belonging to the field of marine vessel parts manufacturing technology. The technical solution involves: after quenching, high-temperature tempering, and rough machining, a W / C / Fe bonding layer and an HfWTiTaB working layer are prepared on the surface of the hydraulic motor parts using laser cladding. This is followed by stress-relief tempering, semi-finishing, and finishing. This surface modification method improves the adhesion between the laser cladding layer and the substrate, achieving a surface hardness of HV2200 or higher, nearly three times higher than traditional surface carburizing heat treatment. Wear rate is reduced by 73-78%, corrosion resistance is improved, and the service life of marine vessel hydraulic motor parts is extended by more than two times. The effective coating process time is only 3-5% of that of traditional carburizing, reducing the maintenance and upkeep costs of the hydraulic motor.

Description

Technical Field

[0001] This invention belongs to the field of marine vessel parts manufacturing technology, and specifically relates to a method for improving the service life of marine vessel hydraulic motors. Background Technology

[0002] The marine environment is an extremely harsh and corrosive environment. Seawater contains many hidden components, such as oxygen, salinity, and microorganisms, as well as a high amount of sodium chloride, making it highly corrosive. Ships and other marine machinery operate at sea for extended periods, resulting in severe corrosion problems. This not only affects the ship's performance, increases production costs, and reduces efficiency, but also poses significant safety hazards.

[0003] Hydraulic motors are crucial actuators in the hydraulic systems of marine vessels, converting the fluid pressure energy provided by a hydraulic pump into the mechanical energy (torque and speed) of their output shaft. With the rapid development of marine shipbuilding technology, marine hydraulic motors are increasingly evolving towards higher pressure, higher speed, and larger flow rates. Due to the unique operating environment at sea, corrosion and wear of the components within marine hydraulic motors are the primary forms of motor damage; currently, the average service life of hydraulic motors in ships is less than one year. Therefore, improving the performance of hydraulic motor component materials is one of the key technologies for the development of modern marine shipbuilding.

[0004] Due to the excellent properties of boride ceramics, such as high hardness, corrosion resistance, and wear resistance, it is expected that preparing boride ceramic coatings on the surface of parts can improve their surface performance and service life, thereby extending the service life of marine hydraulic motors. Chinese invention patent CN114875401A discloses a surface modification method for a high-pressure hydraulic pump gear shaft: after quenching, high-temperature tempering, and rough machining, a Mo / C / Fe bonding layer and a Mo2FeB2 / Mo working layer are prepared on the surface of the hydraulic pump gear shaft blank using laser cladding, 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 requirements of modern marine shipbuilding industry. Summary of the Invention

[0005] This invention provides a method for improving the service life of hydraulic motors for marine vessels. It can significantly improve the surface properties of hydraulic motor parts, enhance their wear resistance and corrosion resistance, effectively increase their service life, extend the maintenance cycle and service life of the product, and reduce the use and maintenance costs of hydraulic motors.

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

[0007] A method to improve the service life of hydraulic motors for marine vessels involves the following steps: After quenching, high-temperature tempering, and rough machining, the hydraulic motor part blanks are clad with W / C / Fe bonding layers and HfWTiTaB working layers on the part surface using laser cladding. This is followed by stress-relief tempering, semi-finishing, and finishing. Specifically, the steps include:

[0008] (1) Machining of hydraulic motor parts: Quenching of hydraulic motor parts blank → High-temperature tempering → Rough machining.

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

[0010] (3) Cladding W / C / Fe bonding layer: Argon protective gas is introduced at a flow rate of 17L / min-20L / min; laser cladding of W / C / Fe bonding layer, the cladding process parameters are: laser power 1360-1550W, scanning speed 160-190mm / min, laser spot diameter 1.5-2.0mm, overlap rate 40-55%, cladding thickness 0.6-1.0mm;

[0011] (4) Cladding HfWTiTaB working layer: Argon protective gas is introduced at a flow rate of 24L / min-26L / min; laser cladding of HfWTiTaB working layer, cladding process parameters are: laser power 2100-2700W, scanning speed 260-280mm / min, laser spot diameter 2.2-3.0mm, overlap rate 34-46%, cladding thickness 2.5-3.5mm;

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

[0013] Preferably, the base material of the hydraulic motor parts is one of 20Cr2Mo, 20CrMnTi, 32Cr2MoV, 35CrW, 40Cr, 45 medium and low carbon steel and their alloy steel.

[0014] Preferably, the W / C / Fe adhesive layer used in step (3) is a composite powder of W, C and Fe, with a particle diameter of 40-80 nm and a weight percentage of 10-15%, 35-40% and 45-55%, respectively.

[0015] Preferably, the cladding working layer used in step (4) is HfWTiTaB powder, and the atomic percentage content of each element in the HfWTiTaB layer is: Hf: 40-50 at.%, W: 25-30 at.%, Ti: 10-15 at.%, Ta: 6-12 at.%, B: 8-15 at.%, and the particle diameter of the HfWTiTaB powder is 60-110 nm.

[0016] Preferably, the W / C / Fe powder used in the cladding adhesive layer in step (3) is ground and mixed in a ball mill for 120-150 min.

[0017] Preferably, the HfWTiTaB composite powder used in the cladding working layer in step (4) is ground and mixed in a ball mill for 100-110 min.

[0018] The aforementioned method for improving the service life of marine hydraulic motors involves preparing an HfWTiTaB composite coating. The HfWTiTaB cladding layer possesses extremely high hardness, excellent corrosion resistance, chemical stability, and wear resistance, thus improving the corrosion resistance and wear resistance of the surface of marine hydraulic motor parts. Hf element enhances the wear resistance and corrosion resistance of the cladding layer; W element improves the hardness and chemical diffusion resistance of the cladding layer, and enhances its oxidation resistance; Ti element improves the hardness, strength, and corrosion resistance of the cladding layer; and Ta element improves the hardness, strength, compressive strength, wear resistance, and corrosion resistance of the cladding layer. Furthermore, a W / C / Fe composite bonding layer is prepared on the workpiece surface using laser cladding. This mitigates the performance differences between the subsequent working layer and the substrate material of the hydraulic motor parts, improves the structural and performance matching between the two, and increases the bonding performance between the laser cladding layer and the substrate material, as well as the impact resistance of the working layer.

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

[0020] The method of improving the service life of marine vessel hydraulic motors according to this invention produces parts with a surface hardness of HV2200 or higher, which is nearly three times higher than the hardness of traditional surface carburizing heat treatment (HV630-670). This method can improve the adhesion performance between the laser cladding layer and the substrate, reduce the wear rate by 73-78%, and the effective coating process time is only 3-5% of that of the traditional carburizing process. It also reduces the maintenance and upkeep costs of hydraulic motors by 75-85% and extends the service life of marine vessel hydraulic motor parts. Attached Figure Description

[0021] Figure 1 This is a schematic diagram of the surface structure of the marine hydraulic motor part prepared according to Embodiment 1 of the present invention. In the figure, 1 is the hydraulic motor part substrate; 2 is the W / C / Fe bonding layer; and 3 is the HfWTiTaB working layer.

[0022] Figure 2 This is the surface optical morphology of the hydraulic motor part prepared in Embodiment 1 of the present invention.

[0023] Figure 3 This is a comparison chart of the average wear rate of the hydraulic motor part prepared in Embodiment 1 of the present invention and the traditional carburized part. Detailed Implementation

[0024] Example 1

[0025] This embodiment provides a surface modification method for a marine hydraulic motor. The base material of the hydraulic motor shaft is 32Cr2MoV medium carbon alloy steel. After quenching, high-temperature tempering, and rough machining, a W / C / Fe bonding layer and an HfWTiTaB working layer are prepared on the surface of the hydraulic motor shaft blank using a laser cladding method. Then, stress-relief tempering, semi-finishing, and finishing are performed.

[0026] Specifically, the steps include the following:

[0027] (1) Machining of hydraulic motor shaft parts: motor shaft part blank → quenching (860℃, water cooling) → high temperature tempering (540℃, water cooling) → rough machining (surface roughness Ra12.5μm, machining dimensions: tolerance lower limit -1mm).

[0028] (2) Surface pretreatment of parts: Remove oil and oxide film from the surface of parts and dry them in a heating furnace.

[0029] (3) Preparation of W / C / Fe composite powder: W, C and Fe composite powder is used, the powder particle diameter is 50nm, and the weight percentages of W, C and Fe are 15%, 40% and 45% respectively. The powder is ground and mixed in a ball mill for 130min.

[0030] (4) Preparation of HfWTiTaB powder: HfWTiTaB powder is used. The atomic percentage content of each element in the HfWTiTaB powder is: Hf: 45 at.%, W: 25 at.%, Ti: 10 at.%, Ta: 12 at.%, B: 8 at.%. The particle diameter of HfWTiTaB powder is 80 nm. The powder is ground and mixed in a ball mill for 110 min.

[0031] (5) Cladding W / C / Fe bonding layer: Argon protective gas is introduced at a flow rate of 20L / min; laser cladding of W / C / Fe bonding layer, the cladding process parameters are: laser power 1500W, scanning speed 180mm / min, laser spot diameter 2.0mm, overlap rate 50%, cladding thickness 1.0mm.

[0032] (6) Cladding HfWTiTaB working layer: Argon protective gas is introduced at a flow rate of 26L / min; laser cladding of HfWTiTaB working layer, the cladding process parameters are: laser power 2600W, scanning speed 280mm / min, laser spot diameter 3.0mm, overlap rate 45%, cladding thickness 3.0mm.

[0033] (7) Post-processing: After the hydraulic motor workpiece has cooled down, stress-relief tempering (505℃, air cooling) is performed → semi-finishing is performed on a lathe (surface roughness Ra3.2μm, machining allowance 0.5mm) → finish machining is performed on a grinding machine (surface roughness Ra1.6μm, machining dimensions to the upper limit of tolerance) → hydraulic motor surface grinding (surface roughness Ra0.8μm, machining dimensions to the tolerance range).

[0034] like Figure 1 The hydraulic motor shaft part obtained in this embodiment has the following structure: a W / C / Fe bonding layer 2 and an HfWTiTaB working layer 3 are sequentially formed from the inside to the outside on the surface of the part substrate 1.

[0035] The surface morphology of the laser-clad HfWTiTaB coated shaft part prepared in this embodiment is as follows: Figure 2 As shown, the microhardness of the coating surface reaches HV2265-2320 (testing equipment: HVS-1000A micro Vickers hardness tester, load 0.5N), which is nearly 3.5 times the surface hardness of the traditional carburizing process (HV625-670). Under the same friction test conditions (HRT-A02 ball-disc friction and wear testing machine, reciprocating linear motion, grinding balls are bearing steel with a surface hardness of HRC55-60, load 80N, friction speed 10mm / s, test time 30min), the wear rate of the laser-clad HfWTiTaB layer prepared by this method is only 1.97-2.14×10⁻⁶. -6 mm 3 The coating process yields a coating density of / N·m, which reduces the wear rate of parts by 70-80% compared to traditional carburizing processes, as shown in Figure 3. Furthermore, the entire effective coating process time is only about 1 hour, which is only 1-3% of the processing time of traditional carburizing. In addition, motor parts prepared using this method can continue to be used normally after 1.5 years, while motor parts prepared using traditional heat treatment processes show severe corrosion and wear after only 5-8 months, affecting the normal operation of the motor.

[0036] Example 2

[0037] This embodiment provides a surface modification method for a marine hydraulic motor. The hydraulic motor shaft component is made of 35CrW medium carbon alloy steel. After quenching, high-temperature tempering, and rough machining, a W / C / Fe bonding layer and an HfWTiTaB working layer are prepared on the surface of the hydraulic motor shaft component using laser cladding. Then, stress-relief tempering, semi-finishing, and finishing are performed.

[0038] Specifically, the steps include the following:

[0039] (1) Machining of hydraulic motor shaft parts: Hydraulic motor shaft parts base blank → Quenching (880℃, water cooling) → High temperature tempering (545℃, oil cooling) → Rough machining (surface roughness Ra12.5μm, machining dimensions: tolerance lower limit -1mm);

[0040] (2) Surface pretreatment of parts: clean the oil and oxide film off the surface of the parts, and dry them in a heating furnace;

[0041] (3) Preparation of W / C / Fe composite powder: W, C and Fe composite powder is used, with a particle diameter of 80 nm. The weight percentages of W, C and Fe are 10%, 35% and 55%, respectively. The powder is ground and mixed in a ball mill for 130 min.

[0042] (4) Preparation of HfWTiTaB composite powder: HfWTiTaB powder is used. The atomic percentage content of each element in the HfWTiTaB powder is: Hf: 45 at.%, W: 25 at.%, Ti: 10 at.%, Ta: 12 at.%, B: 8 at.%. The particle diameter of HfWTiTaB powder is 100 nm. The powder is ground and mixed in a ball mill for 100 min.

[0043] (5) Cladding W / C / Fe bonding layer: Argon protective gas is introduced at a flow rate of 18L / min; laser cladding of W / C / Fe bonding layer, the cladding process parameters are: laser power 1360W, scanning speed 170mm / min, laser spot diameter 1.5mm, overlap rate 40%, cladding thickness 0.6mm.

[0044] (6) Cladding HfWTiTaB working layer: Argon protective gas is introduced at a flow rate of 24L / min; laser cladding of HfWTiTaB working layer, the cladding process parameters are: laser power 2100, scanning speed 260mm / min, laser spot diameter 2.2mm, overlap rate 46%, cladding thickness 2.5mm.

[0045] (7) Post-processing: After the hydraulic motor workpiece has cooled down, stress-relief tempering (550℃, air cooling) is performed → semi-finishing is performed on a lathe (surface roughness Ra1.6μm, machining allowance 0.5mm) → finish machining is performed on a grinding machine (surface roughness Ra0.8μm, machining dimensions to the upper limit of tolerance) → hydraulic motor surface grinding (surface roughness Ra0.4μm, machining dimensions to the tolerance requirement range).

[0046] The surface microhardness of the HfWTiTaB laser-clad rotating shaft part prepared in this embodiment reaches HV2220-2270, which is more than twice that of the part prepared by traditional carburizing process (HV625-670). Under the same friction test conditions, the wear rate of the laser-clad HfWTiTaB layer prepared by this method is 2.16-2.32×10⁻⁶. -6 mm 3 / N·m, which reduces the wear rate of parts treated by traditional carburizing process by more than 70%.

[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. Therefore, the scope of protection of the present invention should be determined by the scope of the claims.

Claims

1. A method of increasing the service life of a hydraulic motor for a marine vessel, characterized in that, The base material of the hydraulic motor part is one of 20Cr2Mo, 20CrMnTi, 32Cr2MoV, 35CrW, 40Cr, 45 medium and low carbon steel and alloy steel thereof; The hydraulic motor part is modified through mechanical processing, surface pretreatment, laser cladding and post-treatment, and specifically comprises the following steps: (1) mechanical processing of the hydraulic motor part: quenching of the hydraulic motor part base blank, high-temperature tempering and rough machining; (2) surface pretreatment of the hydraulic motor part: removing oil stains and oxide film on the surface of the part, rinsing and drying; (3) Cladding W / C / Fe bonding layer: argon gas protection gas, flow rate 17 L / min 20 L / min; laser cladding W / C / Fe bonding layer, cladding process parameters: laser power 1360 1550 W, scanning speed 160 190 mm / min, laser spot diameter 1.5 2.0 mm, overlap rate 40 55 %, cladding thickness 0.6 1.0 mm; (4) Cladding HfW TiTaB working layer: argon gas protection gas, flow rate is 24 L / min 26 L / min; laser cladding HfW TiTaB working layer, cladding process parameters are: laser power 2100 2700 W, scanning speed 260 280 mm / min, laser spot diameter 2.2 3.0 mm, lap rate 34 46%, cladding thickness 2.5 3.5 mm; (5) post-treatment: after the workpiece is cooled, stress relieving tempering is performed, semi-finishing is performed, and finishing is performed; The W / C / Fe composite powder used in the step (3) for cladding the W / C / Fe adhesive layer has a particle diameter of 40 80 nm, and the weight percentage of W, C and Fe is 10 15%, 35 40% and 45 55%, respectively. The W / C / Fe powder used in the step (3) for cladding the adhesive layer is mixed and grinded by a ball mill for 120 150 min. The HfWTiTaB powder used in the step (4) for cladding the working layer has an atomic percentage of each element as follows: Hf: 40 50 at.%, W: 25 30 at.%, Ti: 10 15 at.%, Ta: 6 12 at.%, B: 8 15 at.%, the HfWTiTaB powder particle diameter is 60 110nm; the HfWTiTaB composite powder used in the step (4) of cladding working layer is grinded and mixed by ball mill for 100 110min.

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