Corrosion-resistant alloy steel valve body and preparation method thereof

Abstract

The invention discloses a corrosion-resistant alloy steel valve body and a preparation method, and belongs to the technical field of valve bodies, a valve body blank is subjected to normalizing, quenching and tempering treatment to obtain a valve body semi-finished product, and then the valve body semi-finished product is sequentially etched by using a picosecond laser and a nano laser to obtain the corrosion-resistant alloy steel valve body. A porous and uniform oxidation layer is formed after anodic oxidation treatment, a uniform vanadium carbide and titanium carbide coating is formed on the surface in a laser cladding mode, the porous structure of an oxidation film can improve the adhesive force of the subsequent coating, a composite protection system of the oxidation film and the coating is formed, the corrosion resistance of the corrosion-resistant alloy steel valve body is improved, and the service life of the corrosion-resistant alloy steel valve body is prolonged. And the service life of the corrosion-resistant alloy steel valve body in the slurry pump is prolonged.

Description

Technical Field

[0001] The present invention belongs to the technical field of valve bodies, and specifically relates to a corrosion-resistant alloy steel valve body and a preparation method thereof. Background Art

[0002] As the core component of a fluid control system, the valve body is long-term exposed to high temperature, high pressure and corrosive media (such as acidic oil and gas, seawater containing chlorine, chemical solutions, etc.). The corrosion resistance, mechanical strength and stability of its materials directly determine the service life and safety of the valve. Although traditional valve body materials (such as 304 / 316 austenitic stainless steel, duplex steel 2205) have certain corrosion resistance, they still face problems such as pitting corrosion, stress corrosion cracking (SCC) and intergranular corrosion under extreme working conditions. In deep-sea oil and gas exploitation, the high-concentration Cl- environment is prone to cause the rupture of the stainless steel passivation film, resulting in a sharp increase in the local corrosion rate; while in the high-temperature sulfide medium in the refining industry, ordinary alloy steel is prone to hydrogen sulfide stress corrosion failure, causing valve leakage and even system paralysis.

[0003] Chinese patent application with publication number CN117867413A discloses a valve body and its preparation process. The method includes casting the valve body, heating and forging the annealed valve body, normalizing the forging, quenching the normalized forging, tempering the quenched forging, and surface-treating the tempered forging to obtain the valve body, which improves the service life of the valve body from the selection of raw materials and the process method, improves the overall progress of on-site drilling and production operations, and reduces maintenance costs.

[0004] However, when the valve body is applied to a mud pump, the mud usually contains high-concentration corrosive media (such as Cl - , H2S, CO2 and acidic dissolved substances). These components can directly cause chemical or electrochemical corrosion on the metal surface. At the same time, the hard particles (quartz sand, cuttings) in the mud impact the surface of the valve body of the valve body with high-speed fluid, causing corrosive damage, continuously exposing the fresh metal matrix to the corrosive medium, forming a "wear-corrosion synergistic effect", further aggravating the corrosion of the valve body, and ultimately leading to seal failure. Summary of the Invention

[0005] The purpose of the present invention is to provide a corrosion-resistant alloy steel valve body and a preparation method thereof. By laser etching on the surface of the valve body semi-finished product to form uniformly distributed grooves with a U-shaped cross-section, and then through anodic oxidation treatment, and finally forming a coating by laser cladding to obtain the corrosion-resistant alloy steel valve body, the problem of easy corrosion of the valve body in the mud pump is solved, and the effect of improving the corrosion resistance of the valve body while also improving the strength and adhesion of the coating is achieved.

[0006] The purpose of the present invention can be achieved by the following technical solutions:

[0007] A preparation method of a corrosion-resistant alloy steel valve body, the preparation method comprising: heat-treating a valve body blank to obtain a valve body semi-finished product, and then performing surface treatment, and the specific steps of the surface treatment are as follows:

[0008] Step 1: Treat the valve body semi-finished product by a secondary laser etching process to etch uniformly distributed grooves with a U-shaped cross-section on the surface of the valve body semi-finished product to obtain a porous valve body semi-finished product.

[0009] Step 2: Perform anodic oxidation treatment on the porous valve body semi-finished product to form a uniformly porous oxide film on the surface to obtain an anodized porous valve body semi-finished product.

[0010] Step 3: Mix 12CrNi2 powder, graphite powder, vanadium powder and titanium powder by ball milling to obtain a mixed powder, and coat the mixed powder on the surface of the anodized porous valve body semi-finished product by laser cladding to obtain a corrosion-resistant alloy steel valve body.

[0011] Further, the preparation process of the valve body blank in Step 1 is as follows:

[0012] Melt a pure iron rod, low-carbon ferrochrome, nickel sheet and threaded steel bar at 1500 - 1600 °C under argon protection, then add low-carbon ferrosilicon, low-carbon ferromanganese, high-purity aluminum pellets, phosphorus iron powder, copper pellets and antimony pellets, stir for 3 - 5 min after melting, add basic slag-making materials, keep warm for 2 - 3 h, skim off the floating slag, cool down to 1440 - 1450 °C, cast and form, heat and forge at 900 - 1000 °C, and air-cool to room temperature after rolling to obtain a valve body blank.

[0013] Further, the secondary laser etching process in Step 1 includes the following steps:

[0014] First, use a picosecond laser for etching. When etching with the picosecond laser, the parameters are set as follows: power is 15 W, scanning speed is 300 - 350 mm / s, scanning times are 100 - 120 times. Then, use a nanosecond laser for etching. When etching with the nanosecond laser, the parameters are set as follows: power is 7.5 W, scanning speed is 300 - 350 mm / s, scanning times are 5 - 10 times, defocus amount is +50 μm, and dust removal and air blowing treatments are carried out synchronously during etching.

[0015] Further, the depth of the grooves in Step 1 is 80 - 120 μm, the diameter is 50 - 80 μm, and the gap between adjacent grooves is 200 - 300 μm.

[0016] Further, the preparation process of the anodized porous valve body semi-finished product in Step 2 is as follows:

[0017] Using graphite as the cathode, the semi-finished porous valve body as the anode, and sulfuric acid solution as the electrolyte for anodic oxidation treatment. React for 9 - 12 min under the conditions of 20 - 25 °C and 100 - 200 r / min. The distance between the graphite and the semi-finished porous valve body is 6 - 8 cm, and the anodic oxidation voltage is 50 V. Wash to obtain the semi-finished anodized porous valve body.

[0018] Further, the mass ratio of 12CrNi2 powder, graphite powder, vanadium powder, and titanium powder in step three is 5 - 7:1 - 2:3 - 4.5:2 - 3.

[0019] Further, the coating thickness of laser cladding in step three is 700 - 800 μm.

[0020] Further, the heat treatment includes normalizing, quenching, and tempering.

[0021] A corrosion-resistant alloy steel valve body. The alloy steel valve body blank includes the following elements in weight percentages: C: 0.1 - 0.2%, Si: 0.25 - 0.35%, V: 0.05 - 0.1%, P: 0.08 - 0.12%, Mn: 0.5 - 1%, Al: 0.4 - 0.6%, Ti: 0.02 - 0.04%, Ni: 1.6 - 1.9%, Cr: 0.7 - 1%, Cu: 0.25 - 0.4%, Sb: 0.15 - 0.2%, and the balance is Fe and other impurities.

[0022] The beneficial effects of the present invention:

[0023] 1. The corrosion-resistant alloy steel valve body in the present invention is first obtained by normalizing, quenching, and tempering the valve body blank to obtain a semi-finished valve body, and then the semi-finished valve body is etched successively using a picosecond laser and a nanosecond laser. After anodic oxidation treatment, a porous and uniform oxide layer is formed. A uniform vanadium carbide and titanium carbide coating is formed on the surface by laser cladding. The porous structure of the oxide film can improve the adhesion of the subsequent coating, forming a composite protection system of the oxide film plus the coating, increasing the corrosion resistance of the corrosion-resistant alloy steel valve body, and extending the service life of the corrosion-resistant alloy steel valve body in the mud pump.

[0024] 2. The porous valve body finished product in the present invention is obtained by first etching uniformly distributed pores on the surface of the valve body semi-finished product through a picosecond laser, and then using a nanosecond laser to deepen the original pores through defocus modification, remelting the disordered protrusions at the bottom of the micro-grooves, regularizing the bottom of the irregular micro-grooves, and obtaining grooves with good forming quality. The cross-section of the grooves is U-shaped, with a depth of 80 - 120 μm and a diameter of 50 - 80 μm. It can form a physical lock with the subsequent clad coating material, improving the bonding force of the coating. In addition, the arc-shaped bottom of the U-shaped groove can disperse the thermal stress during the cladding process, reducing the risk of coating cracking, and can also reduce the thermal stress between the valve body and the mud pump during the use of the valve body.

[0025] 3. The anodized porous valve body semi-finished product in the present invention is subjected to anodizing treatment on the basis of the porous valve body semi-finished product, so that a corrosion-resistant oxide film is evenly coated on its surface, delaying the corrosion rate of the alloy steel valve body in the mud pump. In addition, the oxide film has a porous structure, which can increase the adhesion of the coating in the subsequent laser cladding process, thereby improving the strength of the coating, playing a synergistic role with the grooves, and the porous structure has a certain hydrophobicity, which can reduce the penetration of acidic substances in the mud into the valve body, further improving the corrosion resistance of the valve body. Specific embodiments

[0026] The following will clearly and completely describe the technical solutions in the embodiments of the present invention in conjunction with the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative efforts shall fall within the protection scope of the present invention.

[0027] Example 1: This example provides a corrosion-resistant alloy steel valve body, which is prepared by the following steps:

[0028] S1: Add pure iron rods, low-carbon ferrochromium, nickel sheets, and HRB400 threaded steel bars into a pit furnace, keep warm at 475 °C for 35 min, then transfer to an intermediate frequency induction furnace, and melt under the conditions of 1550 °C and argon protection. After melting, add low-carbon ferrosilicon and low-carbon ferromanganese, stir for 4 min after melting, then add high-purity aluminum grains for deoxidation alloying. After skimming the floating slag, add ferrophosphorus powder, copper grains, and antimony grains, stir for 4 min after melting, add basic slag-making materials (the mass ratio of calcium oxide, aluminum oxide, and calcium fluoride is 9:3:1), keep warm for 2.5 h, skim the floating slag, cool down to 1445 °C, cast, and form by casting. Take it out after air-cooling to room temperature, heat and forge at 950 °C, and air-cool to room temperature after rolling to obtain the valve body blank.

[0029] The Sb2O3 oxide layer formed by the oxidation of Sb has a low solubility in weak acids, which helps to improve the corrosion resistance of the valve body blank. At the same time, doping Sb can reduce pitting corrosion on the surface of the valve body blank, inhibit the chemical reaction between chloride ions and iron, thereby reducing the formation of iron-containing chlorides, and can also promote the formation of copper-containing compounds with high corrosion inhibition, further inhibiting anodic and cathodic reactions.

[0030] The valve body blank comprises the following elements by weight percentage: C: 0.15%, Si: 0.3%, V: 0.07%, P: 0.1%, Mn: 0.7%, Al: 0.5%, Ti: 0.03%, Ni: 1.7%, Cr: 0.8%, Cu: 0.3%, Sb: 0.17%, and the balance is Fe and other impurities.

[0031] S2: Rapidly transfer the valve body blank into a heating furnace at 550 °C, raise the temperature to 775 °C within 2.5 h for uniform annealing, then directly raise the temperature to 1025 °C for normalizing. After normalizing, put the valve body blank into a quenching pool. After the surface temperature drops to 310 °C, take it out and let it return to 405 °C, then put it into the quenching pool again. When the surface temperature drops to 260 °C, take it out and let it return to 310 °C. Then put it into the quenching pool again. When the surface temperature drops to 150 °C, take it out and cool it to room temperature. Then put the valve body blank into a tempering furnace, raise the temperature from 325 °C to 550 °C, hold for 30 min, and cool to room temperature. After surface treatment, a valve body semi-finished product is obtained.

[0032] S3: Use a picosecond composite laser processing device to etch the surface of the valve body semi-finished product. The wavelength of the picosecond composite laser processing device is 355 nm. During the processing, first use a picosecond laser for etching. The parameters set for the picosecond laser etching are: power 15 W, scanning speed 325 mm / s, scanning times 110 times. Then use a nanosecond laser for etching. The parameters set for the nanosecond laser etching are: power 7.5 W, scanning speed 325 mm / s, scanning times 7 times, defocus amount +50 μm. During the etching process, dust removal and gas blowing treatments are carried out synchronously to prevent the splashes generated by laser ablation from falling back into the ablation pits again, resulting in an irregular ablation morphology. A groove with good forming quality and a U-shaped cross-section is obtained. The depth of the U-shaped groove is 100 μm, the diameter is 65 μm, and the gap between adjacent U-shaped grooves is 250 μm. They are evenly distributed in an annular array around the center line of the valve body semi-finished product, and a porous valve body semi-finished product is obtained.

[0033] S4: Using graphite as the cathode, the semi-finished porous valve body as the anode, and a sulfuric acid solution with a mass concentration of 15% as the electrolyte, anodic oxidation treatment is carried out. The reaction is carried out for 10 min at 22 °C and 150 r / min. The distance between the graphite and the semi-finished porous valve body is 7 cm, and the reaction area ratio is maintained at 2:1. After applying an electric current, the anodic oxidation voltage is 50 V, and a uniform porous oxide film is formed on the surface of the semi-finished porous valve body. Then, the semi-finished porous valve body is washed with deionized water until neutral to obtain the anodic oxidation semi-finished porous valve body.

[0034] S5: Mix 6 g of 12CrNi2 powder (≥99.5% purity) with a particle size of 50 - 60 μm, 1.5 g of graphite powder with a particle size of 4 - 6 μm, 3.7 g of vanadium powder (≥99.5% purity) with a particle size of 2 - 8 μm, and 2 - 3 g of titanium powder (≥99.5% purity) with a particle size of 4 - 10 μm, and then add them to a ball mill. Ball mill for 2.5 h at 350 r / min, and then uniformly coat it on the anodic oxidation semi-finished porous valve body using sodium silicate water glass as a binder. Then, a continuous coating of VC (vanadium carbide) and TiC (titanium carbide) is formed on the anodic oxidation semi-finished porous valve body by laser cladding. The coating thickness is 750 μm to obtain the corrosion-resistant alloy steel valve body.

[0035] The parameters of laser cladding are: defocus amount is 160 mm, current is 175 A, laser duration is 6.0 ms, frequency is 5 Hz, laser input energy density is 82.5 J / cm 2 , the scanning speed is 3 mm / s, the overlap rate is 9%, and during preparation, argon is used to protect at a flow rate of 17 L / min. The vanadium powder, titanium powder, and graphite powder in-situ synthesize nano-scale VC particles and nano-scale TiC particles under laser irradiation, which have the characteristics of high strength and corrosion resistance and can form a uniform coating on the surface of the corrosion-resistant alloy steel valve body.

[0036] Example 2: This example provides a corrosion-resistant alloy steel valve body, which is prepared through the following steps:

[0037] S1: Add a pure iron rod, low-carbon ferrochrome, nickel sheet, and HRB400 threaded steel bar into a pit furnace, keep it warm at 450 °C for 30 min, and then transfer it to an intermediate frequency induction furnace. Carry out melting under the conditions of 1500 °C and argon protection. After melting is complete, add low-carbon ferrosilicon and low-carbon ferromanganese, stir for 3 min after melting, then add high-purity aluminum pellets for deoxidation alloying. After skimming off the floating slag, add phosphorus iron powder, copper pellets, and antimony pellets, stir for 3 min after melting, add basic slag-making materials (the mass ratio of calcium oxide, aluminum oxide, and calcium fluoride is 9:3:1), keep it warm for 2 h, skim off the floating slag, cool down to 1440 °C, pour, and cast into shape. Take it out after air cooling to room temperature, heat and forge at 900 °C, and air cool to room temperature after rolling to obtain the valve body blank.

[0038] The valve body blank contains the following elements by weight percentage: C: 0.1%, Si: 0.25%, V: 0.05%, P: 0.08%, Mn: 0.5%, Al: 0.4%, Ti: 0.02%, Ni: 1.6%, Cr: 0.7%, Cu: 0.25%, Sb: 0.15%, and the balance is Fe and other impurities.

[0039] S2: Rapidly transfer the valve body blank into a heating furnace at 500°C, raise the temperature to 750°C within 2 h, perform soaking annealing, then directly raise the temperature to 1000°C for normalizing. After normalizing, place the valve body blank in a quenching bath. After the surface temperature drops to 300°C, take it out and let it return to 400°C, then put it back into the quenching bath. When the surface temperature drops to 250°C, take it out and let it return to 300°C, and then put it into the quenching bath again. When the surface temperature drops to 150°C, take it out and cool it to room temperature. Then put the valve body blank into a tempering furnace, raise the temperature from 300°C to 500°C, hold for 30 min, cool to room temperature, and obtain a valve body semi-finished product after surface treatment.

[0040] S3: Use a nanosecond composite laser processing device to etch the surface of the valve body semi-finished product. The wavelength of the nanosecond composite laser processing device is 355 nm. During the processing, first use a picosecond laser for etching. The parameters set for picosecond laser etching are: power of 15 W, scanning speed of 300 mm / s, and scanning times of 100 times. Then use a nanosecond laser for etching. The parameters set for nanosecond laser etching are: power of 7.5 W, scanning speed of 300 mm / s, scanning times of 5 times, and defocus amount of +50 μm. During the etching process, dust removal and air blowing treatments are carried out synchronously to prevent the spatter generated by laser ablation from falling back into the ablation pit again, resulting in an irregular ablation morphology. Obtain a groove with good forming quality and a U-shaped cross-section. The depth of the U-shaped groove is 80 μm, the diameter is 50 μm, the gap between adjacent U-shaped grooves is 200 μm, and they are evenly distributed in an annular array around the center line of the valve body semi-finished product to obtain a porous valve body semi-finished product.

[0041] S4: Use graphite as the cathode, the porous valve body semi-finished product as the anode, and a sulfuric acid solution with a mass concentration of 15% as the electrolyte for anodic oxidation treatment. React for 9 min under the conditions of 20°C and 100 r / min. The distance between the graphite and the porous valve body semi-finished product is 6 cm, and the reaction area ratio is maintained at 2:1. Apply current, and the anodic oxidation voltage is 50 V. A uniform porous oxide film is formed on the surface of the porous valve body semi-finished product. Then wash the porous valve body semi-finished product with deionized water until it is neutral to obtain an anodized porous valve body semi-finished product.

[0042] S5: Mix 12CrNi2 powder (≥99.5% purity) with a particle size of 50 - 60 μm and a weight of 5 g, 1 g of graphite powder with a particle size of 4 - 6 μm, 3 g of vanadium powder (≥99.5% purity) with a particle size of 2 - 8 μm, and 2 g of titanium powder (≥99.5% purity) with a particle size of 4 - 10 μm. After mixing, add them to a ball mill and ball mill for 2 h under the condition of 300 r / min. Then, uniformly coat the semi-finished anodized porous valve body with sodium silicate water glass as the binder, and then form a continuous coating of VC (vanadium carbide) and TiC (titanium carbide) on the semi-finished anodized porous valve body by laser cladding. The coating thickness is 700 μm to obtain a corrosion-resistant alloy steel valve body.

[0043] The parameters of laser cladding are: defocus amount is 160 mm, current is 170 A, laser duration is 6.0 ms, frequency is 5 Hz, laser input energy density is 80 J / cm 2 , the scanning speed is 2 mm / s, the overlapping rate is 8%, and during preparation, it is protected by argon with a flow rate of 15 L / min. Nanoscale VC particles and nanoscale TiC particles are in-situ synthesized from vanadium powder, titanium powder, and graphite powder under laser irradiation, which have the characteristics of high strength and corrosion resistance and can form a uniform coating on the surface of the corrosion-resistant alloy steel valve body.

[0044] Example 3: This example provides a corrosion-resistant alloy steel valve body, which is prepared through the following steps:

[0045] S1: Add pure iron rod, low-carbon ferrochrome, nickel sheet, and HRB400 threaded steel bar into a pit furnace, keep it warm at 500 °C for 40 min, then transfer it to an intermediate frequency induction furnace, and carry out melting under the conditions of 1600 °C and argon protection. After melting, add low-carbon ferrosilicon and low-carbon ferromanganese, stir for 5 min after melting, then add high-purity aluminum particles for deoxidation alloying. After skimming off the floating slag, add ferrophosphorus powder, copper particles, and antimony particles, stir for 5 min after melting, add basic slag-making materials (the mass ratio of calcium oxide, aluminum oxide, and calcium fluoride is 9:3:1), keep it warm for 3 h, skim off the floating slag, cool down to 1450 °C, pour, cast and form, take it out after air cooling to room temperature, heat and forge at 1000 °C, and air cool to room temperature after rolling to obtain a valve body blank.

[0046] The valve body blank includes the following elements in weight percentages: C: 0.2%, Si: 0.35%, V: 0.1%, P: 0.12%, Mn: 1%, Al: 0.6%, Ti: 0.04%, Ni: 1.9%, Cr: 1%, Cu: 0.4%, Sb: 0.2%, and the balance is Fe and other impurities.

[0047] S2: Rapidly transfer the valve body blank into a heating furnace at 600 °C, raise the temperature to 800 °C within 3 h, perform soaking annealing, then directly raise the temperature to 1050 °C for normalizing. Place the valve body blank after normalizing treatment into a quenching bath. After the surface temperature drops to 320 °C, take it out and let it return to 410 °C, then put it back into the quenching bath. When the surface temperature drops to 270 °C, take it out and let it return to 320 °C. Then put it into the quenching bath again. When the surface temperature drops to 150 °C, take it out and cool it to room temperature. Then put the valve body blank into a tempering furnace, raise the temperature from 350 °C to 600 °C, hold for 30 min, cool to room temperature, and obtain a valve body semi-finished product after surface treatment.

[0048] S3: Use a nanosecond composite laser processing equipment to etch the surface of the valve body semi-finished product. The wavelength of the nanosecond composite laser processing equipment is 355 nm. During the processing, first use a picosecond laser to etch. The parameters set for the picosecond laser etching are: power is 15 W, scanning speed is 350 mm / s, and the number of scanning times is 120 times. Then use a nanosecond laser to etch. The parameters set for the nanosecond laser etching are: power is 7.5 W, scanning speed is 350 mm / s, the number of scanning times is 10 times, and the defocus amount is +50 μm. During the etching process, dust removal and air blowing treatments are carried out simultaneously to prevent the spatter generated by laser ablation from falling back into the ablation pit again, resulting in an irregular ablation morphology. Obtain a groove with good forming quality and a U-shaped cross-section. The depth of the U-shaped groove is 120 μm, the diameter is 80 μm, and the gap between adjacent U-shaped grooves is 300 μm. It is evenly distributed in an annular array around the center line of the valve body semi-finished product to obtain a porous valve body semi-finished product.

[0049] S4: Use graphite as the cathode, the porous valve body semi-finished product as the anode, and a sulfuric acid solution with a mass concentration of 15% as the electrolyte for anodic oxidation treatment. React for 12 min under the conditions of 25 °C and 200 r / min. The distance between the graphite and the porous valve body semi-finished product is 8 cm, and the reaction area ratio is maintained at 2:1. Apply current, and the anodic oxidation voltage is 50 V. A uniform porous oxide film is formed on the surface of the porous valve body semi-finished product. Then wash the porous valve body semi-finished product with deionized water until it is neutral to obtain an anodized porous valve body semi-finished product.

[0050] S5: Mix 7 g of 12CrNi2 powder (≥99.5% purity) with a particle size of 50 - 60 μm, 2 g of graphite powder with a particle size of 4 - 6 μm, 4.5 g of vanadium powder (≥99.5% purity) with a particle size of 2 - 8 μm, and 3 g of titanium powder (≥99.5% purity) with a particle size of 4 - 10 μm. After mixing, add them to a ball mill and ball mill for 3 h under the condition of 400 r / min. Then, uniformly coat the semi-finished anodized porous valve body with sodium silicate water glass as the binder, and then form a continuous coating of VC (vanadium carbide) and TiC (titanium carbide) on the semi-finished anodized porous valve body by laser cladding. The coating thickness is 800 μm to obtain a corrosion-resistant alloy steel valve body.

[0051] The parameters of laser cladding are: defocus amount is 160 mm, current is 180 A, laser duration is 6.0 ms, frequency is 5 Hz, laser input energy density is 85 J / cm 2 , scanning speed is 4 mm / s, overlap rate is 10%, and during preparation, it is protected with argon at a flow rate of 20 L / min. Nanoscale VC particles and nanoscale TiC particles are in-situ synthesized from vanadium powder, titanium powder, and graphite powder under laser irradiation, which have the characteristics of high strength and corrosion resistance and can form a uniform coating on the surface of the corrosion-resistant alloy steel valve body.

[0052] The intermediate frequency induction furnace in Examples 1 - 3: The model is LSW - 35KW, purchased from Zhengzhou Lanshuo Electronics Co., Ltd., and the others are all commercially available products.

[0053] Comparative Example 1: On the basis of Example 1, in step S5, use the semi-finished porous valve body prepared in step S3 to replace the semi-finished anodized porous valve body, and keep the other steps unchanged to obtain a corrosion-resistant alloy steel valve body.

[0054] Comparative Example 2: On the basis of Example 1, only use a picosecond laser for etching in step S3. The obtained groove depth is 10 - 20 μm, and the diameter is 5 - 10 μm. Keep the other steps unchanged to obtain a corrosion-resistant alloy steel valve body.

[0055] Comparative Example 3: On the basis of Example 1, when etching with a nanosecond laser in step S3, the parameter settings are: power is 7.5 W, scanning speed is 325 mm / s, scanning times are 50 - 100 times, and defocus amount is +50 μm. The obtained groove depth is 200 - 300 μm, and the diameter is 100 - 150 μm. Keep the other steps unchanged to obtain a corrosion-resistant alloy steel valve body.

[0056] Set a blank control group ck, and the corrosion-resistant alloy steel valve body of ck is the semi-finished valve body prepared in step S2.

[0057] Perform performance tests on the corrosion-resistant alloy steel valve bodies in Examples 1-3, Comparative Examples 1-3, and the CK group:

[0058] Corrosion resistance: Design an accelerated corrosion test with a neutral salt spray test (NSS) according to GB / T 10125-2021 "Artificial Atmosphere Corrosion Test - Salt Spray Test". Use a ZK-60K full-automatic salt spray test machine to conduct a neutral salt spray accelerated corrosion test. Before the test, clean the surface with deionized water and absolute ethanol, then ultrasonically clean in acetone, and then dry in an oven at 50°C for 2 h. After cooling, weigh with an electronic balance, retaining 2 significant figures after the decimal point. Measure three times and take the average value to reduce errors. Use a NaCl solution with a mass fraction of 5% and a pH value of 6.5-7.2. The test period is 72 h, the temperature of the salt spray chamber is set at 45±2°C, the spray pressure is 0.1 MPa, and replenish the NaCl solution every 24 h. Do not open the salt spray chamber during the experiment, and minimize test interruptions. If the salt spray chamber is opened due to special circumstances, the total daily time should not exceed 10 min. After the test is completed, take out the test specimens. To reduce the shedding of corrosion products, place the test specimens in the room to dry naturally for 0.5 h-1 h before cleaning, and then gently clean with deionized water at a temperature not higher than 40°C to remove the residual salt spray solution on the surface of the test specimens, and dry at low temperature in a drying oven.

[0059] Strength performance: Design tensile specimens according to the national standard GB / T228.1-2010 "Metallic materials - Tensile testing - Part 1: Method of test at room temperature". Use a DDL200 universal material testing machine to conduct mechanical property tests on the corrosion-resistant alloy steel valve bodies. Use a 50 kN sensor, and set the tensile rate to 2 mm / min. Test each corrosion-resistant alloy steel valve body three times and take the average value to calculate the tensile strength and yield strength.

[0060] Impact toughness test: Prepare standard V-notch Charpy impact specimens according to the provisions of GB / T229-2007 "Metallic materials - Charpy pendulum impact test method". To ensure the reliability of the experimental results, there are 6 specimens in each group. The impact test equipment is a pendulum impact testing machine (model: PIT452D-4, manufactured by China Kehua Testing Machine Co., Ltd.). The impact test parameters are: voltage 380 V, impact energy 450 J, power 37 KW.

[0061] The test results of each performance are as follows:

[0062] Table 1 Summary of sample performance tests

[0063]

[0064]

[0065] As can be seen from Table 1, the average corrosion rates in Examples 1-3 are lower than those in Comparative Example 1, while the average corrosion rate of the ck group is the highest. In Comparative Example 1, a porous valve body semi-finished product is used to replace the anodized porous valve body semi-finished product, and the ck group does not perform steps such as laser etching, anodizing, and laser cladding. This shows that anodizing and laser etching have a certain synergistic effect in improving the corrosion-resistant alloy steel valve body. The corrosion-resistant effect of single laser etching is limited. The groove depth of the corrosion-resistant alloy steel valve body in Comparative Example 2 is 10-20 μm, and the diameter is 5-10 μm. The groove depth of the corrosion-resistant alloy steel valve body in Comparative Example 3 is 200-300 μm, and the diameter is 100-150 μm. Their corrosion-resistant effects are lower than those in Examples 1-3, indicating that when the groove depth is 80-120 μm and the diameter is 50-80 μm, the corrosion-resistant effect is the best.

[0066] The tensile strength and yield strength in Examples 1-3 and Comparative Examples 1-3 are higher than those of the ck group, indicating that the corrosion-resistant alloy steel valve body after laser etching, anodizing, and laser cladding treatment has been improved in terms of mechanical properties, and the overall strength is better.

[0067] The impact energy in Examples 1-3 is higher than that in Comparative Example 1. In Comparative Example 1, a porous valve body semi-finished product is used to replace the anodized porous valve body semi-finished product, indicating that the surface energy of the alloy steel valve body after anodizing can provide better adhesion for the coating. The impact energy in Comparative Examples 2-3 is lower than that in Examples 1-3, indicating that when the groove depth is 80-120 μm and the diameter is 50-80 μm, the adhesion of the coating is the highest. The impact energy of the ck group is the lowest, indicating that the corrosion-resistant alloy steel valve body after laser etching, anodizing, and laser cladding treatment has better impact resistance. The porous structure of the oxide film can improve the adhesion of the coating, which can not only firmly attach the coating to the surface of the corrosion-resistant alloy steel valve body, but also improve the corrosion-resistant performance of the corrosion-resistant alloy steel valve body together with the coating.

[0068] It should be noted that in this article, terms such as "including", "comprising", or any other variant thereof are intended to cover non-exclusive inclusion, so that a process, method, article, or device including a series of elements not only includes those elements, but also includes other elements not explicitly listed, or elements inherent to such a process, method, article, or device.

[0069] Although the embodiments of the present invention have been shown and described, for those of ordinary skill in the art, it can be understood that various changes, modifications, substitutions, and variations can be made to these embodiments without departing from the principles and spirit of the present invention.

Claims

1. A preparation method of a corrosion-resistant alloy steel valve body, the preparation method comprising: The valve body blank is heat-treated to obtain a semi-finished valve body, and then surface treatment is carried out. It is characterized in that the specific steps of the surface treatment are as follows: Step 1: The semi-finished valve body is processed by a secondary laser etching process to etch grooves with a uniform distribution and a U-shaped cross-section on the surface of the semi-finished valve body, obtaining a porous semi-finished valve body; Step 2: An anodic oxidation treatment is carried out on the porous semi-finished valve body to form a uniformly porous oxide film on the surface, obtaining an anodized porous semi-finished valve body; Step 3: 12CrNi2 powder, graphite powder, vanadium powder and titanium powder are ball-milled and mixed to obtain a mixed powder, and the mixed powder is coated on the surface of the anodized porous semi-finished valve body by laser cladding, obtaining a corrosion-resistant alloy steel valve body.

2. The preparation method of a corrosion-resistant alloy steel valve body according to claim 1, characterized in that, The specific steps of the secondary laser etching process in Step 1 are as follows: First, etching is carried out using a picosecond laser, and then etching is carried out using a nanosecond laser. During etching, dust removal and air blowing treatments are carried out synchronously.

3. The preparation method of a corrosion-resistant alloy steel valve body according to claim 2, characterized in that, When etching with the picosecond laser, the parameter settings are: power is 15W, scanning speed is 300 - 350mm / s, and the number of scanning times is 100 - 120 times; when etching with the nanosecond laser, the parameter settings are: power is 7.5W, scanning speed is 300 - 350mm / s, the number of scanning times is 5 - 10 times, and the defocus amount is +50μm.

4. The preparation method of a corrosion-resistant alloy steel valve body according to claim 1, characterized in that, In Step 1, the depth of the groove is 80 - 120μm, the diameter is 50 - 80μm, and the gap between adjacent grooves is 200 - 300μm.

5. The preparation method of a corrosion-resistant alloy steel valve body according to claim 1, characterized in that, The specific steps of the anodic oxidation treatment in Step 2 are as follows: Using graphite as the cathode, the porous semi-finished valve body as the anode, and a sulfuric acid solution as the electrolyte for anodic oxidation treatment, reacting under the conditions of 20 - 25°C and 100 - 200r / min for 9 - 12min, the distance between the graphite and the porous semi-finished valve body is 6 - 8cm, the anodic oxidation voltage is 50V, washing, obtaining the anodized porous semi-finished valve body.

6. The preparation method of a corrosion-resistant alloy steel valve body according to claim 1, characterized in that, In Step 3, the mass ratio of 12CrNi2 powder, graphite powder, vanadium powder and titanium powder is 5 - 7:1 - 2:3 - 4.5:2 - 3.

7. The preparation method of a corrosion-resistant alloy steel valve body according to claim 1, characterized in that, In Step 3, the coating thickness of the laser cladding is 700 - 800μm.

8. The preparation method of a corrosion-resistant alloy steel valve body according to claim 1, characterized in that, The preparation process of the valve body blank is as follows: A pure iron rod, low-carbon ferrochrome, nickel sheet and threaded steel bar are melted under the conditions of 1500 - 1600°C and argon protection, and then low-carbon ferrosilicon, low-carbon ferromanganese, high-purity aluminum particles, phosphorus iron powder, copper particles and antimony particles are added. After melting, stirring is carried out for 3 - 5min, basic slag-making materials are added, heat preservation is carried out for 2 - 3h, the floating slag is removed, the temperature is lowered to 1440 - 1450°C, casting is carried out, and heating for forging is carried out under the conditions of 900 - 1000°C, and air cooling is carried out after rolling to room temperature, obtaining the valve body blank.

9. The preparation method of a corrosion-resistant alloy steel valve body according to claim 8, characterized in that, The alloy steel valve body blank comprises elements in the following weight percentages: C: 0.1-0.2%, Si: 0.25-0.35%, V: 0.05-0.1%, P: 0.08-0.12%, Mn: 0.5-1%, Al: 0.4-0.6%, Ti: 0.02-0.04%, Ni: 1.6-1.9%, Cr: 0.7-1%, Cu: 0.25-0.4%, Sb: 0.15-0.2%, and the balance is Fe and other impurities.

10. A corrosion-resistant alloy steel valve body, characterized in that, It is prepared by the preparation method of a corrosion-resistant alloy steel valve body according to any one of claims 1-9.

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