A surface treatment process for a valve spool

Abstract

The application discloses a surface treatment process of a valve core, adopts tungsten carbide and nickel-based alloy composite design, and remarkably improves the service life of the valve core under extreme environment. By introducing laser quenching treatment, the surface hardness and wear resistance are enhanced, and defects such as cracks are avoided. By adopting plasma spraying technology, the tungsten carbide powder is melted and high-speed sprayed to the surface of the valve core by means of high-temperature plasma flame, a dense, uniform and well-bonded coating is formed, and the wear resistance, corrosion resistance and sealing performance are improved. In addition, the ion nitriding treatment is used to generate a high-hardness nitride layer, forming a "hard shell-tough core" structure, and prolonging the wear resistance life. Finally, the grinding and polishing treatment is used to improve the surface flatness and smoothness, and ensure the sealing reliability. The application combines multiple advanced processes, remarkably improves the comprehensive performance of the valve core, and guarantees the stable operation of the valve under complex and severe working conditions.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of valve spool surface treatment, and particularly relates to a surface treatment process of a valve spool. BACKGROUND

[0002] As an indispensable fluid control device in industrial production and daily life, valves are widely used in many fields such as petroleum, chemical industry, electric power, water conservancy, construction, etc., and the performance of the valve directly relates to the running efficiency, safety and reliability of the whole system. The valve spool is usually installed inside the valve body, and the flow area between the valve spool and the valve seat is changed through the movement of the valve spool, so as to control the flow, pressure and flow direction of the fluid. The performance requirements of the valve spool are extremely strict. It needs to have good mechanical strength to withstand the high pressure and impact force of the fluid; it needs to have excellent wear resistance because severe friction will occur between the valve spool and the valve seat during the frequent opening and closing of the valve, and if the wear resistance is insufficient, the surface of the valve spool will be worn, which will affect the sealing performance and service life of the valve; at the same time, the valve spool also needs to have excellent corrosion resistance. In many industrial fields, the fluid often contains various corrosive media such as acid, alkali and salt, and if the valve spool has poor corrosion resistance, it will be easily corroded, which will not only change the size and shape of the valve spool, but also reduce its mechanical properties and cause valve leakage and other faults.

[0003] Although the existing valve spool has certain development in design and manufacturing, it still has many defects affecting the performance and service life in actual use. In terms of wear resistance, the materials or surface treatment processes used by some valve spools have poor wear resistance, and over time, the surface of the valve spool is worn, the gap between the valve spool and the valve seat is increased, and valve leakage is caused. In terms of corrosion resistance, the materials of some valve spools are easily chemically reacted in such harsh corrosive environment, which destroys the surface structure, reduces the mechanical strength, changes the size and shape, and affects the sealing performance and normal opening and closing. In terms of high temperature resistance, some valve spools will soften and deform in high temperature environment, and when the temperature exceeds the softening temperature of the material, the strength and hardness will significantly decrease, and the valve spool will deform under the fluid pressure, cannot be well sealed with the valve seat, and leaks, and high temperature will accelerate the oxidation and thermal fatigue of the material and shorten the service life.

[0004] Therefore, the present application provides a surface treatment process of a valve spool, which has important significance. SUMMARY

[0005] The present application aims to provide a surface treatment process of a valve spool to solve the problems in the background.

[0006] To achieve the above-mentioned purpose, the present application provides the following technical scheme:

[0007] A surface treatment process of a valve spool, comprising the following treatment steps:

[0008] Step one, cleaning: the valve core is put into the ultrasonic cleaning tank containing metal oil stain cleaning agent, ultrasonic cleaning is carried out for 15-30 min, then the valve core surface is rinsed with deionized water, and the cleaned valve core is obtained.

[0009] Step two, sand blasting treatment: the cleaned valve core surface is sand blasted by adopting brown corundum sand with a particle size of 80-120 mesh, after sand blasting, the sand particles on the valve core surface are blown clean under the condition that the pressure is 0.4-0.6 MPa, and the pretreated valve core is obtained.

[0010] Step three, ion nitriding treatment: the pretreated valve core is put into the ion nitriding furnace, nitrogen and hydrogen mixed gas with a volume ratio of 7:2 is introduced, ion nitriding treatment is carried out under the condition that the flow rate is 3-6 L / min for 4-6 hours, and the ion nitriding treated valve core is obtained.

[0011] Step four, laser quenching treatment: the ion nitriding treated valve core is taken out and cooled, then the valve core surface is scanned by using laser quenching equipment, and the laser quenching treated valve core is obtained.

[0012] Step five, plasma spraying: 60-70 parts by weight of tungsten carbide powder, 20-30 parts by weight of nickel-based alloy powder and 5-10 parts by weight of alumina powder are uniformly mixed and put into the powder feeder of the plasma spraying equipment, argon gas with a flow rate of 30-50 L / min and hydrogen gas with a flow rate of 5-10 L / min are introduced, the valve core surface is plasma sprayed for 15-45 min, and the plasma sprayed valve core is obtained.

[0013] Step six, grinding and polishing: the surface of the plasma sprayed valve core is ground and polished by using diamond grinding paste for 30-60 min, so that the surface roughness of the valve core reaches Ra0.2-Ra0.5µm, and the surface treated valve core is obtained.

[0014] As a preferred technical scheme of the application, the temperature of ultrasonic cleaning in step one is 50-70℃, and the ultrasonic frequency is 20-40 kHz.

[0015] As a preferred technical scheme of the application, the pressure of sand blasting in step two is 0.4-0.6 MPa, the sand blasting angle is 75°-90°, and the sand blasting distance is 100-150 mm.

[0016] As a preferred technical scheme of the application, the furnace pressure of the ion nitriding furnace in step three is 200-400 Pa, and the temperature is 500-550℃.

[0017] As a preferred technical scheme of the present application, the laser power of the laser quenching treatment in step four is 1500-2000 W, the scanning speed is 5-10 mm / s, the spot diameter is 2-4 mm, and the cooling temperature is 25-35 DEG C.

[0018] As a preferred technical scheme of the present application, the spraying current of the plasma spraying treatment in step five is 500-600 A, the spraying voltage is 50-60 V, the time is 15-45 min, the powder feeding rate is 20-30 g / min, and the spraying thickness is 0.2-0.5 mm.

[0019] As a preferred technical scheme of the present application, the grinding pressure of the grinding and polishing treatment in step six is 0.5-1 MPa.

[0020] Compared with the prior art, the present application has the following beneficial effects:

[0021] 1. The present application utilizes the toughness of the nickel-based alloy to improve the impact resistance of the coating, and utilizes the heat insulation and chemical stability of the aluminum oxide to further optimize the high-temperature oxidation resistance and corrosion resistance of the coating, so that the service life of the valve core under extreme working environment is significantly improved.

[0022] 2. The laser quenching treatment introduced in the valve core surface treatment process of the present application can rapidly heat the surface of the valve core to above the phase transition point, and then realize rapid quenching through self-cooling to form a layer of fine and uniform martensite structure on the surface of the valve core, thereby further improving the hardness and wear resistance of the surface of the valve core.

[0023] 3. The plasma spraying technology introduced in the valve core surface treatment process of the present application can fully melt the coating material in the high-temperature plasma flame and spray it at high speed onto the surface of the valve core to form a dense, uniform and well-bonded coating on the surface of the valve core, thereby further improving the wear resistance, corrosion resistance and sealing performance of the surface of the valve core. DETAILED DESCRIPTION

[0024] The technical solutions in the embodiments of the present application will be described below in a clear and complete manner. Obviously, the described embodiments are only a part of the embodiments of the present application, rather than all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative labor fall within the scope of protection of the present application.

[0025] Tungsten carbide (WC) is a kind of cermet compound formed by covalent bond between tungsten and carbon elements, which has extremely high hardness and wear resistance (microhardness up to 2000-2500HV, second only to diamond), excellent high-temperature stability (melting point about 2870℃, still maintaining high hardness above 1000℃) and good corrosion resistance, these characteristics make it become the core material in the fields of hard alloy, wear-resistant coating and cutting tool, etc. In the plasma spraying process of this patent, tungsten carbide powder as the main component, through the high-temperature melting of plasma flame, high-speed impact on the surface of valve spool, forming a dense coating which is firmly combined with the substrate, its high hardness characteristics significantly improve the wear resistance of valve spool in high pressure and high frequency friction environment.

[0026] Sand blasting is a kind of mechanical processing method which uses high-speed moving sand particles to impact the surface of workpiece. It can remove the oxide skin, rust, dirt and increase the surface roughness. After sand blasting, the sand particles on the surface of valve spool are blown away under the condition of 0.4-0.6MPa, at this time the sand particles have completed the task of surface treatment and are blown away from the surface. And the subsequent ion nitriding, laser quenching, plasma spraying and other processing steps are based on the rough surface formed by sand blasting to further improve the performance of valve spool, the rough surface formed by sand blasting is beneficial to the combination of subsequent coating and substrate.

[0027] Ion nitriding treatment is a kind of efficient surface strengthening technology realized by glow discharge in low pressure environment, its core mechanism is to place the pretreated valve spool in a mixed atmosphere containing nitrogen and hydrogen, and then use high voltage electric field to excite gas ionization at high temperature after vacuumizing, the high-energy nitrogen ions formed by this process bombard the surface of valve spool at a frequency of tens of thousands per second, this continuous ion impact not only directly injects nitrogen atoms into the surface layer of substrate, but also removes the surface oxide film through sputtering effect, significantly improves the penetration efficiency of nitrogen atoms; in this process, nitrogen atoms react with iron, chromium and other elements in the valve spool substrate to form a high-hardness nitride layer mainly composed of ε phase (Fe 2-3 N) and γ' phase (Fe4N), while the compressive stress generated by ion bombardment and the reduction effect of hydrogen gas inhibit the formation of brittle phase, so that a thick and dense nitride layer is formed on the surface, and at the same time, a diffusion transition zone with decreasing hardness from substrate to surface is formed, this unique "hard shell-tough core" structure not only ensures the wear resistance of valve spool sealing surface under high pressure and friction, but also avoids the problems of surface peeling or toughness reduction often seen in traditional nitriding process through the stress buffering effect of diffusion layer, finally, it significantly prolongs the wear life of valve spool while maintaining the impact toughness of the substrate.

[0028] The laser quenching process relies on a high-energy density laser beam as a heat source. When the laser beam precisely irradiates the surface of the valve core, it can rapidly heat the local area of the valve core surface to a temperature above the phase transition point of the material within a very short time. This heating process is extremely rapid, allowing the heat to be conducted to the interior of the valve core in large quantities, thereby achieving rapid local surface heating and minimizing the impact on the overall performance of the valve core. Subsequently, the laser irradiation is stopped, and the valve core surface cools rapidly by its own heat conduction, achieving the quenching process. This self-cooling method does not require additional cooling medium, avoiding problems caused by uneven cooling medium or difficulty in accurately controlling the cooling speed. During the rapid cooling process, the metal material on the surface of the valve core undergoes a phase change, forming a layer of fine and uniform martensite structure. The martensite structure has high hardness and high strength characteristics, which greatly enhances the wear resistance of the valve core surface compared to the original matrix structure of the valve core. In the process of frequent opening and closing of the valve, severe friction occurs between the valve core and the valve seat. The high-hardness martensite structure can effectively resist this friction and wear, reducing material loss on the surface of the valve core and extending the service life of the valve core. At the same time, due to the extremely fast cooling speed of the laser quenching process, the temperature of the valve core surface drops sharply within a short time, resulting in relatively small thermal stress. Compared with traditional quenching processes, this smaller thermal stress can effectively prevent cracks, deformation and other defects on the surface of the valve core. The occurrence of cracks can seriously affect the sealing performance and structural strength of the valve core, while the laser quenching process reduces the risk of crack formation from the source, ensuring the integrity and reliability of the valve core. In addition, the laser quenching process also has good local processing characteristics. It can accurately control the irradiation area and parameters of the laser according to the actual working conditions and performance requirements of different parts of the valve core, achieving selective strengthening of the valve core surface. This improves the performance of critical parts while reducing production costs and improving production efficiency, providing a strong guarantee for the stable operation of the valve core in complex and harsh working conditions.

[0029] Plasma spraying technology is an advanced surface coating preparation method, that is, using non-transferred arc flame as a heat source, refractory metal or non-metal powder material is sent into the arc to be quickly melted, and is sprayed into extremely fine particles at extremely high speed to impact on the surface of the welding part, thereby forming a very thin coating with special properties. The coating can significantly improve the wear resistance of the valve core surface, its high hardness and good anti-adhesive wear and abrasive wear capacity can effectively resist the wear of the valve core by the medium containing particles; it can enhance the corrosion resistance, the dense structure of the coating can prevent the direct contact of the corrosive medium with the valve core matrix, and part of the coating material itself has good chemical stability, which can protect the valve core in a severe corrosive environment; it can also improve the sealing performance, the uniformity and flatness of the coating can reduce the leakage channel between the valve core and the valve seat, improve the sealing reliability of the valve, thereby prolonging the service life of the valve and ensuring the stable operation of the system.

[0030] The grinding and polishing treatment can remove the small protrusions and burrs remaining on the surface of the valve core after spraying, further improve the flatness and smoothness of the surface of the valve core, and ensure that the valve core and the sealing ring can achieve good sealing contact.

[0031] The application provides a surface treatment process for a valve core.

[0032] Embodiment one:

[0033] A surface treatment process for a valve core comprises the following treatment steps:

[0034] Step one, cleaning: the valve core is placed in an ultrasonic cleaning tank containing a metal oil stain cleaning agent, ultrasonic cleaning is performed, the cleaning temperature is 60 DEG C, the ultrasonic frequency is 30 kHz, and the cleaning time is 22 min, then the valve core surface is rinsed with deionized water, and a cleaned valve core is obtained.

[0035] Step two, sand blasting treatment: the surface of the cleaned valve core is sandblasted by using brown corundum sand with a particle size of 100 mesh, the pressure is 0.5 MPa, the sandblasting angle is 82 DEG, the sandblasting distance is 125 mm, after sandblasting, the sand particles on the surface of the valve core are blown clean under the condition of a pressure of 0.5 MPa, and a pretreated valve core is obtained.

[0036] Step three, ion nitriding treatment: the pretreated valve core is placed in an ion nitriding furnace, a mixed gas of nitrogen and hydrogen (volume ratio 7:2) is introduced, the flow rate is 4.5 L / min, ion nitriding treatment is performed, the pressure in the furnace is 300 Pa, the temperature is 525 DEG C, and the time is 5 hours, and a valve core treated by ion nitriding is obtained.

[0037] Step four, laser quenching treatment: the valve core after ion nitriding treatment is taken out and cooled to 30℃, and then the surface of the valve core is scanned by using a laser quenching device, the laser power is 1750W, the scanning speed is 7.5mm / s, and the spot diameter is 3mm, so as to obtain the valve core after laser quenching treatment.

[0038] Step five, plasma spraying: 65 parts by weight of tungsten carbide powder, 25 parts by weight of nickel-based alloy powder and 7.5 parts by weight of alumina powder are uniformly mixed and put into the powder feeder of the plasma spraying device, argon gas is introduced at a flow rate of 40L / min, hydrogen gas is introduced at a flow rate of 7.5L / min, the valve core surface is treated by plasma spraying, the spraying current is 550A, the spraying voltage is 55V, the time is 30min, the powder feeding rate is 25g / min, and the spraying thickness is 0.35mm, so as to obtain the valve core after plasma spraying.

[0039] Step six, grinding and polishing: the surface of the valve core after plasma spraying is treated by grinding and polishing using diamond grinding paste, the grinding pressure is 0.75MPa, the time is 45min, so that the surface roughness of the valve core reaches Ra0.35μm, and the surface treated valve core is obtained.

[0040] Example two:

[0041] A surface treatment process of a valve core, comprising the following treatment steps:

[0042] Step one, cleaning: the valve core is put into an ultrasonic cleaning tank containing metal oil stain cleaning agent, and ultrasonic cleaning is performed, the cleaning temperature is 50℃, the ultrasonic frequency is 20kHz, and the cleaning time is 15min, then the valve core surface is rinsed with deionized water, and the cleaned valve core is obtained.

[0043] Step two, sand blasting treatment: the surface of the cleaned valve core is sand blasted by using brown corundum sand with a particle size of 80 mesh, the pressure is 0.4MPa, the sand blasting angle is 75°, the sand blasting distance is 100mm, after sand blasting, the sand particles on the surface of the valve core are blown away under the condition of 0.4MPa pressure, and the pretreated valve core is obtained.

[0044] Step three, ion nitriding treatment: the pretreated valve core is put into an ion nitriding furnace, a mixed gas of nitrogen and hydrogen (volume ratio of 7:2) is introduced at a flow rate of 3L / min, ion nitriding treatment is carried out, the pressure in the furnace is 200Pa, the temperature is 500℃, and the time is 4 hours, so as to obtain the valve core after ion nitriding treatment.

[0045] Step four, laser quenching treatment: the valve core after ion nitriding treatment is taken out and cooled to 25℃, and then the surface of the valve core is scanned by using a laser quenching device, the laser power is 1500W, the scanning speed is 5mm / s, and the spot diameter is 2mm, so as to obtain the valve core after laser quenching treatment.

[0046] Step five, plasma spraying: 60 parts by weight of tungsten carbide powder, 20 parts by weight of nickel-based alloy powder and 5 parts by weight of alumina powder are uniformly mixed and put into the powder feeder of the plasma spraying equipment, argon gas is introduced at a flow rate of 30L / min, hydrogen gas is introduced at a flow rate of 5L / min, the valve core surface is treated by plasma spraying, the spraying current is 500A, the spraying voltage is 50V, the time is 15min, the powder feeding rate is 20g / min, and the spraying thickness is 0.2mm, so as to obtain the valve core after plasma spraying.

[0047] Step six, grinding and polishing: the surface of the valve core after plasma spraying is treated by grinding and polishing using diamond grinding paste, the grinding pressure is 0.5MPa, the time is 30min, the surface roughness of the valve core is 0.2μm, and the surface treated valve core is obtained.

[0048] Example three:

[0049] A surface treatment process of a valve core, comprising the following treatment steps:

[0050] Step one, cleaning: the valve core is put into an ultrasonic cleaning tank containing metal oil stain cleaning agent, and ultrasonic cleaning is performed, the cleaning temperature is 70℃, the ultrasonic frequency is 40kHz, and the cleaning time is 30min, then the valve core surface is rinsed with deionized water, and the cleaned valve core is obtained.

[0051] Step two, sand blasting treatment: the surface of the cleaned valve core is sandblasted by using brown corundum sand with a particle size of 120 mesh, the pressure is 0.6MPa, the sandblasting angle is 90°, the sandblasting distance is 150mm, after sandblasting, the sand particles on the surface of the valve core are blown away under the condition of 0.6MPa, and the pretreated valve core is obtained.

[0052] Step three, ion nitriding treatment: the pretreated valve core is put into an ion nitriding furnace, a mixed gas of nitrogen and hydrogen (volume ratio of 7:2) is introduced at a flow rate of 6L / min, ion nitriding treatment is carried out, the pressure in the furnace is 400Pa, the temperature is 550℃, and the time is 6 hours, so as to obtain the valve core after ion nitriding treatment.

[0053] Step four, laser quenching treatment: the valve core after ion nitriding treatment is taken out and cooled to 35℃, and then laser quenching equipment is used to scan the surface of the valve core, the laser power is 2000W, the scanning speed is 10mm / s, and the spot diameter is 4mm, so as to obtain the valve core after laser quenching treatment.

[0054] Step five, plasma spraying: 70 parts by weight of tungsten carbide powder, 30 parts by weight of nickel-based alloy powder and 10 parts by weight of alumina powder are uniformly mixed and put into the powder feeder of the plasma spraying equipment, argon gas is introduced at a flow rate of 50L / min and hydrogen gas is introduced at a flow rate of 10L / min, the valve core surface is treated by plasma spraying, the spraying current is 500-600A, the spraying voltage is 60V, the time is 45min, the powder feeding rate is 30g / min, and the spraying thickness is 0.5mm, so as to obtain the valve core after plasma spraying.

[0055] Step six, grinding and polishing: diamond grinding paste is used to grind and polish the surface of the valve core after plasma spraying, the grinding pressure is 1MPa, the time is 60min, so that the surface roughness of the valve core reaches Ra0.5μm, and the surface treated valve core is obtained.

[0056] Comparative example one:

[0057] The difference from example one is that ion nitriding treatment is not used in the surface treatment process of the valve core.

[0058] Comparative example two:

[0059] The difference from example one is that laser quenching treatment is not used in the surface treatment process of the valve core.

[0060] Comparative example three:

[0061] The difference from comparative example one is that plasma spraying is not used in the surface treatment process of the valve core.

[0062] The valve cores obtained in the above examples and comparative examples are subjected to wear test according to GB / T 12444-2006 "Metallic materials-Wear testing method-Ring-block sliding wear test", high temperature performance test according to GB / T 228.2-2015 "Metallic materials-Tensile testing-Part 2: High temperature testing methods", and corrosion test according to GB / T 10125-2012 "Artificial atmosphere corrosion test-Salt spray test", and the results are shown in Table 1.

[0063] Table 1

[0064]

[0065] As shown in the results of Table 1, the wear amount of the valve core prepared in Comparative Example 1 is significantly increased compared with Examples 1, 2 and 3, and the results show that the nitride layer formed by ion nitriding is the key to improve the wear resistance of the valve core, and the surface of the valve core without ion nitriding treatment is prone to adhesive wear and fatigue spalling, and the wear resistance is decreased. Compared with Examples 1, 2 and 3, the number and average length of thermal fatigue cracks of the valve core prepared in Comparative Example 2 are significantly increased, and the results show that the gradient hardening layer formed by laser quenching can relieve thermal stress, and the subsurface softening of the valve core without laser quenching treatment is prone to cause thermal fatigue cracks, and the thermal impact resistance is decreased. Compared with Examples 1, 2 and 3, the corrosion rate of the valve core prepared in Comparative Example 3 is significantly increased, and the results show that the Ni-3 alloy layer formed by plasma spraying can provide a dense corrosion barrier, and the valve core without plasma spraying is directly exposed to the corrosion environment, and the corrosion resistance is decreased.

[0066] The above are only specific embodiments of the present application, but the technical features of the present application are not limited thereto. Any simple change, equivalent replacement or modification made on the basis of the present application to solve the basically same technical problem and realize the basically same technical effect is covered in the protection scope of the present application.

Claims

1. A surface treatment process for a valve trim, characterized by, The method comprises the following steps: Step 1: cleaning: the valve core is placed in an ultrasonic cleaning tank containing a metal oil stain cleaning agent, and ultrasonic cleaning is performed for 15-30 min, and then the valve core surface is rinsed with deionized water to obtain a cleaned valve core; Step 2: sand blasting: the cleaned valve core surface is sand blasted using brown corundum sand with a particle size of 80-120 mesh, and after sand blasting, the sand particles on the valve core surface are blown clean under a pressure of 0.4-0.6 MPa to obtain a pretreated valve core; Step 3: ion nitriding treatment: the pretreated valve core is placed in an ion nitriding furnace, and a mixed gas of nitrogen and hydrogen with a volume ratio of 7:2 is introduced, and ion nitriding treatment is performed at a flow rate of 3-6 L / min for 4-6 hours to obtain an ion nitriding treated valve core; Step 4: laser quenching treatment: the ion nitriding treated valve core is taken out and cooled, and then the valve core surface is scanned using a laser quenching device to obtain a laser quenching treated valve core; Step 5: plasma spraying: 60-70 parts by weight of tungsten carbide powder, 20-30 parts by weight of nickel-based alloy powder and 5-10 parts by weight of alumina powder are uniformly mixed and fed into the powder feeder of the plasma spraying equipment, argon gas with a flow rate of 30-50 L / min and hydrogen gas with a flow rate of 5-10 L / min are introduced, and the valve core surface is plasma sprayed for 15-45 min to obtain a plasma sprayed valve core; Step 6: grinding and polishing: the valve core surface after plasma spraying is ground and polished using diamond grinding paste for 30-60 min to make the valve core surface roughness reach Ra0.2-Ra0.5 μm, and a surface treated valve core is obtained.

2. A valve trim surface treatment process in accordance with claim 1, characterized by, The ultrasonic cleaning temperature in step 1 is 50-70℃, and the ultrasonic frequency is 20-40 kHz.

3. The valve trim surface treatment process of claim 1 wherein, The sand blasting pressure in step 2 is 0.4-0.6 MPa, the sand blasting angle is 75°-90°, and the sand blasting distance is 100-150 mm.

4. The valve trim surface treatment process of claim 1 wherein, The furnace pressure of the ion nitriding furnace in step 3 is 200-400 Pa, and the temperature is 500-550℃.

5. The valve trim surface treatment process of claim 1 wherein, The laser quenching treatment in step 4 has a laser power of 1500-2000 W, a scanning speed of 5-10 mm / s, a spot diameter of 2-4 mm, and a cooling temperature of 25-35℃.

6. The valve trim surface treatment process of claim 1 wherein, The plasma spraying treatment in step 5 has a spraying current of 500-600 A, a spraying voltage of 50-60 V, a powder feeding rate of 20-30 g / min, and a spraying thickness of 0.2-0.5 mm.

7. The valve trim surface treatment process of claim 1 wherein, The grinding pressure in the grinding and polishing treatment in step 6 is 0.5-1 MPa.

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