CN112760591B - High-corrosion-resistance stainless steel and preparation method thereof - Google Patents

Abstract

The invention belongs to the technical field of stainless steel surface modification, in particular to high corrosion resistance stainless steel and a preparation method thereof, and the method comprises the following steps: s1: placing the stainless steel ingot in a high-temperature smelting furnace, heating to 1600 ℃ for high-temperature smelting for 30-40min, heating to 1700 ℃ for heat preservation smelting for 10-15min, continuously carrying out slag skimming treatment in the smelting process, and obtaining refined steel after smelting is completed; s2: fine polishing the surface of the steel product subjected to refining in the step S1 by using 500-mesh fine sand paper, sequentially carrying out oil removal, primary water washing, acid washing and ultrasonic vibration water washing on the steel product after polishing treatment, introducing the steel product into a dryer, and preheating the steel product to 50-60 ℃ in the process of drying treatment; s3: placing the rare earth alloy material into an ethanol solution, introducing the ethanol solution into a planetary ball mill, controlling the rotating speed of the planetary ball mill to be 500-600r/min for high-speed grinding, introducing the ground rare earth alloy material into a molecular sieve for filtering, controlling the pore diameter of the molecular sieve to be 350-500 meshes, and filtering to obtain catalyst powder.

Description

High-corrosion-resistance stainless steel and preparation method thereof

Technical Field

The invention belongs to the technical field of stainless steel surface modification, and particularly relates to high-corrosion-resistance stainless steel and a preparation method thereof.

Background

In the prior art, the surface of the steel is easy to be corroded by environment in the long-time use process, so that the steel is corroded, the strength of the steel is reduced, and the steel is further broken and damaged, therefore, the corrosion resistance of the stainless steel is extremely important, the corrosion resistance of the surface of the stainless steel is improved, most of the surface of the stainless steel is subjected to corrosion resistance treatment, the nitriding technology is a high-quality modification method for the surface of the steel, but the nitriding technology is carried out at a higher temperature, the permeation efficiency of nitrogen element is slower, the nitriding technology is lower, the permeation efficiency of nitrogen element is further improved, the stainless steel is coated with a rare earth alloy catalyst, the permeation efficiency of nitrogen element is further accelerated, but part of rare earth alloy catalyst can be coated on the surface of the steel although the rare earth alloy catalyst has certain magnetism, but the utilization degree of the rare earth alloy catalyst is reduced due to the fact that part of rare earth alloy catalyst is subjected to the magnetic fading phenomenon at a high temperature, the rare earth alloy is directly adhered to the surface of the steel at a high temperature, and the separation of a catalyst layer and the stainless steel is not convenient after the nitriding treatment.

Nitriding method disclosed in China patent publication, application number: 2012102414905A catalyst is prepared first and is preset on the clean surface of a workpiece, then the workpiece is treated for 5 to 50 hours at 300 to 700 ℃ in a nitrogen-containing atmosphere, and finally the catalyst attached to the surface of the workpiece is cleaned and recovered.

In view of the above, the present invention has developed a highly corrosion-resistant stainless steel and a method for preparing the same for solving the above-mentioned technical problems.

Disclosure of Invention

In order to overcome the defects of the prior art, the problems that the connectivity between a rare earth catalyst and a workpiece is poor and the uniformity degree is insufficient when the rare earth catalyst is coated on the surface of the workpiece in the prior art, the nitriding is easy to carry out unevenly, and simultaneously, the catalyst falls off from the surface of the workpiece along with the continuous action of high temperature, so that the nitriding rate is easy to continuously slow down, and the nitriding process efficiency is not facilitated are solved.

The technical scheme adopted for solving the technical problems is as follows: the invention relates to a preparation method of high corrosion-resistant stainless steel, which comprises the following steps:

s1: placing the stainless steel ingot in a high-temperature smelting furnace, heating to 1600 ℃ for high-temperature smelting for 30-40min, heating to 1700 ℃ for heat preservation smelting for 10-15min, continuously carrying out slag skimming treatment in the smelting process, and obtaining refined steel after smelting is completed;

s2: fine polishing the surface of the steel product subjected to refining in the step S1 by using 500-mesh fine sand paper, sequentially carrying out oil removal, primary water washing, acid washing and ultrasonic vibration water washing on the steel product after polishing treatment, introducing the steel product into a dryer, and preheating the steel product to 50-60 ℃ in the process of drying treatment;

s3: placing the rare earth alloy material into an ethanol solution, introducing the ethanol solution into a planetary ball mill, controlling the rotating speed of the planetary ball mill to be 500-600r/min for high-speed grinding, introducing the ground rare earth alloy material into a molecular sieve for filtering, controlling the pore diameter of the molecular sieve to be 350-500 meshes, and filtering to obtain catalyst powder;

s4: mixing and stirring the prepared catalyst powder, clay and deionized water according to the proportion of 3:1:3, stirring until the mixture is in a viscous paste shape to prepare a catalyst coating, uniformly coating the catalyst coating on the surface of the steel preheated in the step S2, and sending the steel into a nitriding kettle;

s5: introducing nitrogen or ammonia gas serving as a nitrogen source into a nitriding kettle, controlling the temperature in the nitriding kettle to be constant at 350-400 ℃ and the air pressure to be 1.5-2MPa, performing 8-20H nitriding treatment, placing steel into deionized water for flushing after the nitriding treatment is finished, removing a surface catalyst layer to obtain high corrosion resistant stainless steel, and simultaneously performing carbon dioxide impact on flushing liquid and concentration to obtain a catalyst coating;

in the prior art, the surface of the steel is easy to be corroded by environment in the long-time use process, so that the steel is corroded, the strength of the steel is reduced, and the steel member is broken and damaged, therefore, the corrosion resistance of the stainless steel is extremely important, the corrosion resistance of the surface of the stainless steel is improved, most of the surface of the stainless steel is subjected to corrosion resistance treatment, the nitriding technology is a high-quality modification method for the surface of the steel, but the nitriding technology is carried out at a higher temperature, the permeation efficiency of nitrogen element is slower, the nitriding technology is lower, the permeation efficiency of nitrogen element is further improved, the stainless steel is coated with a rare earth alloy catalyst, the permeation efficiency of nitrogen element is further accelerated, but part of rare earth alloy catalyst can be coated on the surface of the steel although the rare earth alloy catalyst has certain magnetism, but the utilization degree of the rare earth alloy catalyst is reduced due to the fact that part of rare earth alloy catalyst is subjected to the magnetic fading phenomenon at a high temperature, the rare earth alloy is directly adhered to the surface of the steel at a high temperature, and the separation of a catalyst layer and the stainless steel is not convenient after the nitriding treatment;

when the stainless steel is in operation, the stainless steel ingot is purified in a high-temperature molten state, low-temperature impurities contained in the stainless steel are removed, the surface of the stainless steel is polished by sand paper, so that the surface of the stainless steel is separated out in a high-temperature and cooling process and oxidized impurities generated by reaction with oxygen are removed, the stainless steel is preheated while being subjected to degreasing, primary washing, acid washing and ultrasonic vibration washing, and further, when the surface of the steel is coated with a catalyst, the catalyst can be quickly combined with the surface of the stainless steel, clay and rare earth alloy powder are simultaneously used for mixing, rare earth alloy powder is coated by slurry formed by clay and deionized water, the rare earth alloy powder is further dispersed more uniformly, when the mixture formed by blending the rare earth alloy powder and the clay is contacted with the surface of the stainless steel, the catalyst can be uniformly dispersed on the surface of the stainless steel by using the high-quality adhesion and fluidity of the clay slurry, the catalyst is further, after the stainless steel coated with the catalyst is introduced into a nitriding kettle, the catalyst can be quickly combined with the surface of the stainless steel under the high-temperature effect, the rare earth alloy powder is further, the rare earth alloy powder is quickly separated from the surface by the moisture and the moisture of the clay, and the rare earth alloy powder is further, and the rare earth alloy particles are further adsorbed on the surface of the stainless steel by the stainless steel, and the surface is further, and the rare earth alloy particles can be quickly absorbed by the moisture and can be quickly absorbed by the stainless steel surface layer by the rare earth alloy powder and the rare earth alloy powder due to the high-temperature-nitrogen alloy powder, the method has the advantages that the problem that the combination surface of rare earth alloy powder and stainless steel is gradually reduced along with the nitriding reaction is effectively avoided, the nitriding reaction rate is effectively kept all the time, the nitriding reaction on the surface of the stainless steel is effectively promoted, meanwhile, after the nitriding process is completed, water flow is utilized, as the clay has water absorbability, the catalytic layer condensed on the surface of the stainless steel is separated out under the high-temperature action, water absorption expansion is achieved, and then water flow impact is matched, the catalytic layer is quickly separated from the surface of the stainless steel, compared with the prior art, the catalytic layer is separated from the stainless steel through polishing, the damage to the nitriding layer on the surface of the stainless steel is effectively avoided, meanwhile, the catalyst can be effectively collected, the loss degree of the catalyst is effectively reduced, the cost of the nitriding process is effectively reduced, the catalyst itself has viscosity due to the addition of the clay, and the catalyst and the stainless steel material can be directly combined through the viscosity of the clay when the stainless steel material which is not provided with ferromagnetism in part is coated, and the application range of the catalyst is wider.

Preferably, the clay in S4 is modified clay prepared by montmorillonite powder and gum arabic according to a ratio of 3:1; the montmorillonite powder is montmorillonite powder clay with the thickness of less than 0.005 mm;

during operation, the clay prepared from montmorillonite powder and Arabic gum is mixed to prepare modified clay, on one hand, the clay prepared from montmorillonite powder clay has the characteristics of strong viscosity and good high temperature resistance, meanwhile, arabic gum has certain thickening property and thickening property, arabic gum and montmorillonite powder are mixed to prepare clay, so that the clay has better viscosity in aqueous solution, meanwhile, the prepared catalyst has better fluidity due to smaller particle size, the catalyst has better fluidity when being coated on the surface of stainless steel, the combination of the catalyst and the surface of stainless steel is further more compact, and meanwhile, covering effect can be formed on finer pore diameter and concave of a stainless steel member, the coverage of the nitriding process on the surface modification of the stainless steel is more careful, and the modifying effect of the nitriding process on the surface of the stainless steel is enhanced.

Preferably, the preparation method of the rare earth alloy material in the step S3 comprises the following steps:

i: dissolving an aluminum alloy ingot in a high-temperature smelting furnace flushed with inert protective gas, controlling the temperature of the high-temperature smelting furnace to be increased to 900-1200 ℃ for high-temperature smelting, continuously carrying out slag skimming treatment in the smelting process, and controlling the smelting and slag skimming treatment for 30-35min; smelting an aluminum alloy ingot at a high temperature, and then effectively removing oxidized impurities contained in the aluminum alloy ingot, so that the impurity content in the finally prepared rare earth alloy is reduced, the reduction of the absorption capacity of a catalyst on nitrogen particles is avoided, and the promotion effect of the catalyst on a nitriding process is reduced;

II: introducing rare earth powder with 15-20% of the mass of the aluminum alloy liquid into a high-temperature furnace filled with inert gas, controlling the temperature in the high-temperature furnace to rise to 200-300 ℃, heating the rare earth powder for 15-20min, and introducing the rare earth powder into the aluminum alloy liquid in step I after the rare earth powder is magnetically cooled; the method comprises the steps of carrying out demagnetizing treatment on the rare earth powder at high temperature, so that the dispersing effect of the rare earth powder in the aluminum alloy liquid is better, the content of rare earth elements in the prepared rare earth alloy powder is more uniform, the modification of the surface of the stainless steel by the nitriding process is more compact, and the situation that a certain gap exists in the prepared nitriding layer, so that the corrosion resistance enhancement effect on the surface of the stainless steel is reduced is avoided;

III: stirring an aluminum alloy liquid added with rare earth powder, rapidly cooling the aluminum alloy liquid through a powder metallurgy technology to obtain a powder rare earth alloy, placing the powder rare earth alloy in a magnetic field formed by a coil filled with direct current, carrying out magnetizing treatment, and controlling the magnetizing time to be 15-20min to obtain a rare earth alloy material; the prepared powder rare earth alloy is magnetized in the magnetic field of the energizing coil, so that the magnetism of the rare earth alloy is recovered under the action of high temperature by utilizing the characteristics of ferromagnetism and magnetic force of the rare earth powder, so that the rare earth alloy material has certain magnetism, the prepared catalyst and stainless steel have adsorption effect, and the adsorption effect of the catalyst on the surface of the stainless steel is effectively enhanced.

Preferably, the steel in the S4 is electrified and magnetized before being coated with the catalyst coating, and the magnetic force on the surface of the magnetized steel is controlled to be 0.3-0.5N;

during operation, through carrying out the circular telegram magnetization to stainless steel surface, make the steel temporarily possess certain magnetism, and then in the coating process of catalyst, make the catalyst on stainless steel surface's bonding effect better, and then make the catalyst layer that the catalyst formed on stainless steel surface more even effectively, the stainless steel surface carries out circular telegram magnetization simultaneously can also effectually make stainless steel surface's hole, the magnetism of depressed part and the magnetism on level surface have certain difference, and then make the catalyst can assemble in the depressed part effectively, and cladding makes the nitriding carry out more meticulously.

Preferably, the clay also contains alkaline particles of which the total mass is 15-18 percent and sodium bicarbonate and sodium carbonate are mixed according to the proportion of 5:1; during operation, adding sodium bicarbonate and sodium carbonate powder into clay, after the catalyst finishes coating on the surface of stainless steel, introducing the stainless steel into a nitriding kettle, decomposing sodium bicarbonate in the heating process to form fine carbon dioxide bubbles, and allowing the carbon dioxide bubbles to overflow outwards, so that fine pores are formed on the surface of the catalyst, the contact area between a catalyst layer and a nitrogen atmosphere is effectively large, the rate of the nitriding process is effectively promoted, and meanwhile, the alkaline environment formed by sodium bicarbonate and sodium carbonate can also effectively inhibit rare earth alloy oxidation, and meanwhile, the alkaline environment is also favorable for continuous use of clay.

Preferably, the concentration in S5 is performed by adopting a low-temperature drying technology, and the drying temperature is controlled to be maintained at 5-8 ℃; during operation, the low-temperature drying technology can effectively prevent the magnetic formation damage of rare earth alloy, and simultaneously can effectively reduce the solubility of clay in water, so as to effectively avoid the loss of viscosity of clay in the long-time use process, form invalid clay and negatively affect the overall performance of the catalyst.

The high corrosion resistant stainless steel comprises the following elements in proportion:

0.03-0.05% of Mn, 0.01-0.015% of Cr, 0.08-0.1% of Ti, 0.15-0.2% of Nb, 0.1-0.3% of S, 0.2-0.4% of Ni and the balance of Fe.

The beneficial effects of the invention are as follows:

1. according to the high corrosion resistance stainless steel and the preparation method thereof, adhesion of clay is utilized to effectively prevent the demagnetized rare earth alloy powder from separating from the surface of the stainless steel, so that the catalyst layer is always and tightly attached to the stainless steel layer, the gradual reduction of the bonding surface of the rare earth alloy powder and the stainless steel along with the nitriding reaction is effectively avoided, the nitriding reaction rate is always and effectively maintained, the nitriding reaction of the surface of the stainless steel is effectively promoted, meanwhile, after the nitriding process is finished, the impact of water flow is utilized, and the clay has water absorption, so that the catalytic layer precipitated and condensed on the surface of the stainless steel under the high temperature effect is expanded by water absorption, and is further matched with the water flow impact, so that the catalytic layer is separated from the surface of the stainless steel rapidly.

2. According to the high corrosion resistance stainless steel and the preparation method thereof, a certain amount of sodium bicarbonate and sodium carbonate powder is added into clay, after the catalyst is coated on the surface of the stainless steel, the stainless steel is introduced into a nitriding kettle, in the heating process, sodium bicarbonate is decomposed to form fine carbon dioxide bubbles, and the carbon dioxide bubbles overflow outwards, so that fine pores are formed on the surface of the catalyst, the contact area between a catalyst layer and a nitrogen atmosphere is effectively increased, and the proceeding rate of a nitriding process is effectively promoted.

Drawings

The invention is further described below with reference to the accompanying drawings.

FIG. 1 is a process flow diagram of a method of making a highly corrosion resistant stainless steel;

FIG. 2 is a process flow diagram of a method of preparing a rare earth alloy material;

Detailed Description

The invention is further described in connection with the following detailed description in order to make the technical means, the creation characteristics, the achievement of the purpose and the effect of the invention easy to understand.

As shown in fig. 1 to 2, the preparation method of the high corrosion-resistant stainless steel comprises the following steps:

s1: placing the stainless steel ingot in a high-temperature smelting furnace, heating to 1600 ℃ for high-temperature smelting for 30-40min, heating to 1700 ℃ for heat preservation smelting for 10-15min, continuously carrying out slag skimming treatment in the smelting process, and obtaining refined steel after smelting is completed;

s2: fine polishing the surface of the steel product subjected to refining in the step S1 by using 500-mesh fine sand paper, sequentially carrying out oil removal, primary water washing, acid washing and ultrasonic vibration water washing on the steel product after polishing treatment, introducing the steel product into a dryer, and preheating the steel product to 50-60 ℃ in the process of drying treatment;

s3: placing the rare earth alloy material into an ethanol solution, introducing the ethanol solution into a planetary ball mill, controlling the rotating speed of the planetary ball mill to be 500-600r/min for high-speed grinding, introducing the ground rare earth alloy material into a molecular sieve for filtering, controlling the pore diameter of the molecular sieve to be 350-500 meshes, and filtering to obtain catalyst powder;

s4: mixing and stirring the prepared catalyst powder, clay and deionized water according to the proportion of 3:1:3, stirring until the mixture is in a viscous paste shape to prepare a catalyst coating, uniformly coating the catalyst coating on the surface of the steel preheated in the step S2, and sending the steel into a nitriding kettle;

s5: introducing nitrogen or ammonia gas serving as a nitrogen source into a nitriding kettle, controlling the temperature in the nitriding kettle to be constant at 350-400 ℃ and the air pressure to be 1.5-2MPa, performing 8-20H nitriding treatment, placing steel into deionized water for flushing after the nitriding treatment is finished, removing a surface catalyst layer to obtain high corrosion resistant stainless steel, and simultaneously performing carbon dioxide impact on flushing liquid and concentration to obtain a catalyst coating;

in the prior art, the surface of the steel is easy to be corroded by environment in the long-time use process, so that the steel is corroded, the strength of the steel is reduced, and the steel member is broken and damaged, therefore, the corrosion resistance of the stainless steel is extremely important, the corrosion resistance of the surface of the stainless steel is improved, most of the surface of the stainless steel is subjected to corrosion resistance treatment, the nitriding technology is a high-quality modification method for the surface of the steel, but the nitriding technology is carried out at a higher temperature, the permeation efficiency of nitrogen element is slower, the nitriding technology is lower, the permeation efficiency of nitrogen element is further improved, the stainless steel is coated with a rare earth alloy catalyst, the permeation efficiency of nitrogen element is further accelerated, but part of rare earth alloy catalyst can be coated on the surface of the steel although the rare earth alloy catalyst has certain magnetism, but the utilization degree of the rare earth alloy catalyst is reduced due to the fact that part of rare earth alloy catalyst is subjected to the magnetic fading phenomenon at a high temperature, the rare earth alloy is directly adhered to the surface of the steel at a high temperature, and the separation of a catalyst layer and the stainless steel is not convenient after the nitriding treatment;

when the stainless steel is in operation, the stainless steel ingot is purified in a high-temperature molten state, low-temperature impurities contained in the stainless steel are removed, the surface of the stainless steel is polished by sand paper, so that the surface of the stainless steel is separated out in a high-temperature and cooling process and oxidized impurities generated by reaction with oxygen are removed, the stainless steel is preheated while being subjected to degreasing, primary washing, acid washing and ultrasonic vibration washing, and further, when the surface of the steel is coated with a catalyst, the catalyst can be quickly combined with the surface of the stainless steel, clay and rare earth alloy powder are simultaneously used for mixing, rare earth alloy powder is coated by slurry formed by clay and deionized water, the rare earth alloy powder is further dispersed more uniformly, when the mixture formed by blending the rare earth alloy powder and the clay is contacted with the surface of the stainless steel, the catalyst can be uniformly dispersed on the surface of the stainless steel by using the high-quality adhesion and fluidity of the clay slurry, the catalyst is further, after the stainless steel coated with the catalyst is introduced into a nitriding kettle, the catalyst can be quickly combined with the surface of the stainless steel under the high-temperature effect, the rare earth alloy powder is further, the rare earth alloy powder is quickly separated from the surface by the moisture and the moisture of the clay, and the rare earth alloy powder is further, and the rare earth alloy particles are further adsorbed on the surface of the stainless steel by the stainless steel, and the surface is further, and the rare earth alloy particles can be quickly absorbed by the moisture and can be quickly absorbed by the stainless steel surface layer by the rare earth alloy powder and the rare earth alloy powder due to the high-temperature-nitrogen alloy powder, the method has the advantages that the problem that the combination surface of rare earth alloy powder and stainless steel is gradually reduced along with the nitriding reaction is effectively avoided, the nitriding reaction rate is effectively kept all the time, the nitriding reaction on the surface of the stainless steel is effectively promoted, meanwhile, after the nitriding process is completed, water flow is utilized, as the clay has water absorbability, the catalytic layer condensed on the surface of the stainless steel is separated out under the high-temperature action, water absorption expansion is achieved, and then water flow impact is matched, the catalytic layer is quickly separated from the surface of the stainless steel, compared with the prior art, the catalytic layer is separated from the stainless steel through polishing, the damage to the nitriding layer on the surface of the stainless steel is effectively avoided, meanwhile, the catalyst can be effectively collected, the loss degree of the catalyst is effectively reduced, the cost of the nitriding process is effectively reduced, the catalyst itself has viscosity due to the addition of the clay, and the catalyst and the stainless steel material can be directly combined through the viscosity of the clay when the stainless steel material which is not provided with ferromagnetism in part is coated, and the application range of the catalyst is wider.

As an embodiment of the present invention, wherein the clay in S4 is a modified clay prepared by mixing montmorillonite powder and gum arabic in a ratio of 3:1; the montmorillonite powder is montmorillonite powder clay with the thickness of less than 0.005 mm;

during operation, the clay prepared from montmorillonite powder and Arabic gum is mixed to prepare modified clay, on one hand, the clay prepared from montmorillonite powder clay has the characteristics of strong viscosity and good high temperature resistance, meanwhile, arabic gum has certain thickening property and thickening property, arabic gum and montmorillonite powder are mixed to prepare clay, so that the clay has better viscosity in aqueous solution, meanwhile, the prepared catalyst has better fluidity due to smaller particle size, the catalyst has better fluidity when being coated on the surface of stainless steel, the combination of the catalyst and the surface of stainless steel is further more compact, and meanwhile, covering effect can be formed on finer pore diameter and concave of a stainless steel member, the coverage of the nitriding process on the surface modification of the stainless steel is more careful, and the modifying effect of the nitriding process on the surface of the stainless steel is enhanced.

As an embodiment of the present invention, the preparation method of the rare earth alloy material in S3 includes the following steps:

i: dissolving an aluminum alloy ingot in a high-temperature smelting furnace flushed with inert protective gas, controlling the temperature of the high-temperature smelting furnace to be increased to 900-1200 ℃ for high-temperature smelting, continuously carrying out slag skimming treatment in the smelting process, and controlling the smelting and slag skimming treatment for 30-35min; smelting an aluminum alloy ingot at a high temperature, and then effectively removing oxidized impurities contained in the aluminum alloy ingot, so that the impurity content in the finally prepared rare earth alloy is reduced, the reduction of the absorption capacity of a catalyst on nitrogen particles is avoided, and the promotion effect of the catalyst on a nitriding process is reduced;

II: introducing rare earth powder with 15-20% of the mass of the aluminum alloy liquid into a high-temperature furnace filled with inert gas, controlling the temperature in the high-temperature furnace to rise to 200-300 ℃, heating the rare earth powder for 15-20min, and introducing the rare earth powder into the aluminum alloy liquid in step I after the rare earth powder is magnetically cooled; the method comprises the steps of carrying out demagnetizing treatment on the rare earth powder at high temperature, so that the dispersing effect of the rare earth powder in the aluminum alloy liquid is better, the content of rare earth elements in the prepared rare earth alloy powder is more uniform, the modification of the surface of the stainless steel by the nitriding process is more compact, and the situation that a certain gap exists in the prepared nitriding layer, so that the corrosion resistance enhancement effect on the surface of the stainless steel is reduced is avoided;

III: stirring an aluminum alloy liquid added with rare earth powder, rapidly cooling the aluminum alloy liquid through a powder metallurgy technology to obtain a powder rare earth alloy, placing the powder rare earth alloy in a magnetic field formed by a coil filled with direct current, carrying out magnetizing treatment, and controlling the magnetizing time to be 15-20min to obtain a rare earth alloy material; the prepared powder rare earth alloy is magnetized in the magnetic field of the energizing coil, so that the magnetism of the rare earth alloy is recovered under the action of high temperature by utilizing the characteristics of ferromagnetism and magnetic force of the rare earth powder, so that the rare earth alloy material has certain magnetism, the prepared catalyst and stainless steel have adsorption effect, and the adsorption effect of the catalyst on the surface of the stainless steel is effectively enhanced.

As one embodiment of the invention, the steel in the S4 is electrified and magnetized before being coated with the catalyst coating, and the magnetic force of the magnetized steel surface is controlled to be 0.3-0.5N;

during operation, through carrying out the circular telegram magnetization to stainless steel surface, make the steel temporarily possess certain magnetism, and then in the coating process of catalyst, make the catalyst on stainless steel surface's bonding effect better, and then make the catalyst layer that the catalyst formed on stainless steel surface more even effectively, the stainless steel surface carries out circular telegram magnetization simultaneously can also effectually make stainless steel surface's hole, the magnetism of depressed part and the magnetism on level surface have certain difference, and then make the catalyst can assemble in the depressed part effectively, and cladding makes the nitriding carry out more meticulously.

As an embodiment of the invention, the clay also contains alkaline particles of which the total mass is 15-18% of the mixture of sodium bicarbonate and sodium carbonate according to the proportion of 5:1; during operation, adding sodium bicarbonate and sodium carbonate powder into clay, after the catalyst finishes coating on the surface of stainless steel, introducing the stainless steel into a nitriding kettle, decomposing sodium bicarbonate in the heating process to form fine carbon dioxide bubbles, and allowing the carbon dioxide bubbles to overflow outwards, so that fine pores are formed on the surface of the catalyst, the contact area between a catalyst layer and a nitrogen atmosphere is effectively large, the rate of the nitriding process is effectively promoted, and meanwhile, the alkaline environment formed by sodium bicarbonate and sodium carbonate can also effectively inhibit rare earth alloy oxidation, and meanwhile, the alkaline environment is also favorable for continuous use of clay.

As an embodiment of the present invention, wherein the concentration in S5 is performed using a low temperature drying technique, and the drying temperature is controlled to be maintained at 5-8 ℃; during operation, the low-temperature drying technology can effectively prevent the magnetic formation damage of rare earth alloy, and simultaneously can effectively reduce the solubility of clay in water, so as to effectively avoid the loss of viscosity of clay in the long-time use process, form invalid clay and negatively affect the overall performance of the catalyst.

The high corrosion resistant stainless steel comprises the following elements in proportion: 0.03-0.05% of Mn, 0.01-0.015% of Cr, 0.08-0.1% of Ti, 0.15-0.2% of Nb, 0.1-0.3% of S, 0.2-0.4% of Ni and the balance of Fe.

The specific implementation flow is as follows:

during operation, through purifying the stainless steel ingot in a high-temperature molten state, remove the low-temperature impurity contained in the stainless steel, the stainless steel surface is polished by sand paper, and then the surface of the steel is separated out in the high-temperature and cooling process and is removed by oxidizing impurities generated by the reaction with oxygen, and the stainless steel is preheated while being subjected to degreasing, primary water washing, acid washing, ultrasonic vibration water washing and drying, and then the catalyst can be quickly combined with the surface of the stainless steel when the surface of the steel is coated with the catalyst, meanwhile clay and rare earth alloy powder are used for mixing, the rare earth alloy powder is coated by slurry formed by clay and deionized water, so that the rare earth alloy powder is more uniformly dispersed, when the mixture formed by blending the rare earth alloy powder and the clay is contacted with the surface of the stainless steel, the catalyst can be uniformly dispersed on the surface of the stainless steel by using the high-quality adhesion property and fluidity of the clay slurry, after the stainless steel coated with the catalyst is put into a nitriding kettle, the catalyst is gradually evaporated in the high-temperature condition, the rare earth alloy powder is gradually separated from the surface of the stainless steel by the evaporation catalyst, and the rare earth alloy powder is effectively separated from the surface of the stainless steel by the moisture, and the rare earth alloy powder is effectively absorbed by the stainless steel surface, and the rare earth alloy powder is prevented from being closely adhered to the surface by the surface of the stainless steel, and the surface of the stainless steel is further reduced by the high-temperature alloy powder, and the magnetic particle is effectively absorbed by the rare earth alloy powder and the surface is gradually separated from the surface by the surface of the stainless steel surface, the rate of nitriding reaction is further kept always and effectively, the nitriding reaction on the surface of the stainless steel is further promoted effectively, meanwhile, after the nitriding process is finished, water flow is utilized to impact at the moment, as clay has water absorbability, the catalytic layer precipitated and condensed on the surface of the stainless steel is further caused to absorb water and expand under the high temperature effect, and then the catalytic layer is separated from the surface of the stainless steel rapidly due to the cooperation of water flow impact.

In order to verify the strength of the catalyst prepared by the method of the present invention in promoting effect on the nitriding process of stainless steel, examples 1 to 2 were specially set up;

example 1

Respectively selecting three stainless steel ingots with the same weight and 5cm x 2cm, numbering A, B and C, and sequentially polishing, degreasing, primary washing, pickling, ultrasonic oscillation washing and drying the three stainless steel ingots for later use;

(1) Weighing 30g of LaFe 11 Si 2, ceFe 11 Ti and PrFe 4 Al 8 mixed rare earth powder according to a ratio of 1:1:1 by using an electronic balance scale, uniformly mixing, adding the mixture into a high-temperature smelting kettle containing 70g of aluminum alloy liquid, controlling the temperature in the high-temperature smelting kettle to be 950 ℃, stirring at a speed of 60-80r/min, uniformly stirring for 10-15min, preparing an alloy solution into rare earth alloy powder with a particle size of 0.1-0.2mm by a powder metallurgy technology after stirring, mixing the rare earth alloy powder with ethanol and ethylene glycol according to a ratio of 3:3:2, preparing catalyst slurry, and uniformly coating the catalyst slurry on the surface of a stainless steel ingot with the number of A for later use;

(2) Weighing 30g of LaFe 11 Si 2, ceFe 11 Ti and PrFe 4 Al 8 mixed rare earth powder according to a ratio of 1:1:1 by using an electronic balance scale, uniformly mixing the rare earth powder, adding the mixture into a high-temperature smelting kettle containing 70g of aluminum alloy liquid, controlling the temperature in the high-temperature smelting kettle to be 950 ℃, stirring at a speed of 60-80r/min, uniformly stirring for 10-15min, preparing an alloy solution into rare earth alloy powder with a particle size of 0.1-0.2mm by using a powder metallurgy technology after stirring, mixing the rare earth alloy powder, gum arabic, sodium bicarbonate and sodium carbonate according to a ratio of 3:1:0.64:0.16 to prepare clay, uniformly mixing the rare earth alloy powder, the clay and deionized water according to a ratio of 3:2:3 to prepare catalyst slurry, and uniformly coating the catalyst slurry on the surface of a stainless steel ingot with a number of B for later use;

(3) Weighing 30g of LaFe 11 Si 2, ceFe 11 Ti and PrFe 4 Al 8 mixed rare earth powder according to a ratio of 1:1:1 by using an electronic balance scale, calcining the mixed rare earth alloy powder in a high-temperature furnace at 260 ℃ for 15-20min, adding the mixed rare earth alloy powder into a high-temperature smelting kettle containing 70g of aluminum alloy liquid, controlling the temperature in the high-temperature smelting kettle to be 950 ℃ and the stirring speed to be 60-80r/min, uniformly stirring for 10-15min, preparing an alloy solution into rare earth alloy powder with a particle size of 0.1-0.2mm by using a powder metallurgy technology after stirring, mixing montmorillonite powder, gum arabic, sodium bicarbonate and sodium carbonate according to a ratio of 3:1:0.64:0.16 to prepare clay, mixing the rare earth alloy powder with clay and deionized water according to a ratio of 3:2:3 to prepare catalyst slurry, and uniformly coating the catalyst slurry on the surface of a stainless steel ingot with the number of C for standby;

(4) Introducing nitrogen into a nitriding kettle which uses nitrogen as a nitrogen source, controlling the temperature in the nitriding kettle to be 350-400 ℃ and the air pressure to be 1.5-2MPa, nitriding, taking out stainless steel ingots respectively after nitriding, cutting along the axis of the stainless steel by using a laser cutting technology, selecting the same 5-point position of the section of the stainless steel, detecting the thickness of the nitriding layer generated on the surface of the stainless steel by using a laser range finder, averaging the thickness of the 5-point nitriding layer on the section of the same stainless steel, and outputting experimental data;

table 1 (nitriding layer thickness)

Example 2

Respectively selecting three stainless steel ingots with the same components, the same volume and the mass of 1kg, numbering A, B and C, and sequentially polishing, degreasing, washing with water, pickling, oscillating with ultrasonic waves, washing with water and drying for later use;

(1) Weighing 30g of LaFe 11 Si 2, ceFe 11 Ti and PrFe 4 Al 8 mixed rare earth powder according to a ratio of 1:1:1 by using an electronic balance scale, uniformly mixing, adding the mixture into a high-temperature smelting kettle containing 70g of aluminum alloy liquid, controlling the temperature in the high-temperature smelting kettle to be 950 ℃, stirring at a speed of 60-80r/min, uniformly stirring for 10-15min, preparing an alloy solution into rare earth alloy powder with a particle size of 0.1-0.2mm by using a powder metallurgy technology after stirring, mixing the rare earth alloy powder with ethanol and ethylene glycol according to a ratio of 3:3:2 to prepare catalyst slurry, uniformly coating the catalyst slurry on the surface of a stainless steel ingot with the number of A, introducing nitrogen into a nitriding kettle with nitrogen as a nitrogen source, the temperature in the nitriding kettle is controlled to be constant at 350-400 ℃ and the air pressure is controlled to be 1.5-2MPa, nitriding treatment is carried out for 15H, sand paper is used for polishing the surface of a stainless steel ingot after the nitriding treatment is finished, deionized water is used for cleaning the surface of the stainless steel ingot after the polishing is finished, the polished product and the cleaned water slurry are magnetically separated to obtain 91.5g of a magnetic separation product, the washed stainless steel ingot is placed in 0.5mol/LHCL solution for soaking for 24H, the stainless steel is weighed for 993.25g by an electronic balance after the soaking is finished, and the data is calculated by using a formula (weight after 1-weight after test/weight after test), so that the catalyst loss rate and the stainless steel loss rate are output;

(2) Weighing 30g of LaFe 11 Si 2, ceFe 11 Ti and PrFe 4 Al 8 mixed rare earth powder according to a ratio of 1:1:1 by using an electronic balance scale, uniformly mixing, adding the mixture into a high-temperature smelting kettle containing 70g of aluminum alloy liquid, controlling the temperature in the high-temperature smelting kettle to be 950 ℃, stirring at a speed of 60-80r/min, uniformly stirring for 10-15min, preparing the alloy solution into rare earth alloy powder with a particle size of 0.1-0.2mm by using a powder metallurgy technology after stirring, mixing the rare earth alloy powder, the gum arabic, sodium bicarbonate and sodium carbonate according to a ratio of 3:1:0.64:0.16 to prepare clay, mixing the rare earth alloy powder, the clay and deionized water according to a ratio of 3:2:3 to prepare catalyst slurry, uniformly coating catalyst slurry on the surface of a stainless steel ingot with the number of B, introducing the stainless steel ingot into a nitriding kettle using nitrogen as a nitrogen source, controlling the temperature in the nitriding kettle to be constant at 350-400 ℃ and the air pressure to be 1.5-2MPa, carrying out nitriding treatment for 15H, flushing the surface of the stainless steel by using deionized water after the nitriding treatment is finished, carrying out magnetic separation on flushing liquid to obtain 96.4g of magnetic separation product, soaking the flushed stainless steel ingot in 0.5mol/LHCL solution for 24H, washing and drying the stainless steel after soaking, weighing the stainless steel by using an electronic balance scale for 995.45g, applying the data to a formula (weight after 1-test/weight after test) for calculation, and further outputting the catalyst loss rate and the stainless steel loss rate;

(3) Weighing 30g of LaFe 11 Si 2, ceFe 11 Ti and PrFe 4 Al 8 mixed rare earth powder according to a ratio of 1:1:1 by using an electronic balance scale, calcining the mixed rare earth alloy powder in a high-temperature furnace at 260 ℃ for 15-20min, adding the mixed rare earth alloy powder into a high-temperature smelting kettle containing 70g of aluminum alloy liquid, controlling the temperature in the high-temperature smelting kettle to be 950 ℃ and the stirring speed to be 60-80r/min, uniformly stirring for 10-15min, preparing the alloy solution into rare earth alloy powder with a particle size of 0.1-0.2mm by using a powder metallurgy technology after stirring, mixing montmorillonite powder, gum arabic, sodium bicarbonate and sodium carbonate according to a ratio of 3:1:0.64:0.16 to prepare clay, mixing the rare earth alloy powder with clay and deionized water according to a ratio of 3:2:3, preparing catalyst slurry, uniformly coating the catalyst slurry on the surface of a stainless steel ingot with the number of B, introducing the stainless steel ingot into a nitriding kettle using nitrogen as a nitrogen source, controlling the temperature in the nitriding kettle to be constant at 350-400 ℃ and the air pressure to be 1.5-2MPa, nitriding 15H, flushing the surface of the stainless steel by using deionized water after the nitriding treatment is finished, magnetically separating flushing liquid to obtain 97.2g of a magnetic separation product, immersing the flushed stainless steel ingot in 0.5mol/LHCL solution for 24H, washing and drying the stainless steel after the immersing is finished, weighing the stainless steel with an electronic balance with the weight of 996.80g, calculating the data by using a formula (weight after 1-test/weight after test), and outputting the catalyst loss rate and the stainless steel loss rate;

TABLE 2 loss rate of catalyst and stainless steel

According to the three groups of comparison tests in the table 1, the catalyst prepared by the method can effectively accelerate nitriding rate and maintain good catalytic effect with time by coating according to the method, meanwhile, according to the experimental data in the table 2, the loss rate of the catalyst before and after the catalyst is used can be effectively reduced, the cost of the catalyst is effectively saved, and meanwhile, the corrosion resistance of the stainless steel by using the catalyst and the coating method is obviously improved.

The foregoing has shown and described the basic principles, principal features and advantages of the invention. It will be understood by those skilled in the art that the present invention is not limited to the embodiments described above, and that the above embodiments and descriptions are merely illustrative of the principles of the present invention, and various changes and modifications may be made without departing from the spirit and scope of the invention, which is defined in the appended claims. The scope of the invention is defined by the appended claims and equivalents thereof.

Claims (5)

1. A preparation method of high corrosion resistance stainless steel is characterized in that: the preparation method of the high corrosion resistance stainless steel comprises the following steps:

s1: placing the stainless steel ingot in a high-temperature smelting furnace, heating to 1600 ℃ for high-temperature smelting for 30-40min, heating to 1700 ℃ for heat preservation smelting for 10-15min, continuously carrying out slag skimming treatment in the smelting process, and obtaining refined steel after smelting is completed;

s2: fine polishing the surface of the steel product subjected to refining in the step S1 by using 500-mesh fine sand paper, sequentially carrying out oil removal, primary water washing, acid washing and ultrasonic vibration water washing on the steel product after polishing treatment, introducing the steel product into a dryer, and preheating the steel product to 50-60 ℃ in the process of drying treatment;

s3: placing rare earth alloy materials into an ethanol solution, introducing the ethanol solution into a planetary ball mill, controlling the rotating speed of the planetary ball mill to be 500-600r/min for high-speed grinding, introducing the ground rare earth alloy materials into a molecular sieve for filtering, controlling the pore diameter of the molecular sieve to be 350-500 meshes, and filtering to obtain catalyst powder;

s4: mixing and stirring the prepared catalyst powder, clay and deionized water according to the proportion of 3:2:3, stirring until the mixture is in a viscous paste shape to prepare a catalyst coating, uniformly coating the catalyst coating on the surface of the steel preheated in the step S2, and sending the steel into a nitriding kettle;

s5: introducing nitrogen or ammonia gas serving as a nitrogen source into a nitriding kettle, controlling the temperature in the nitriding kettle to be constant at 350-400 ℃ and the air pressure to be 1.5-2MPa, nitriding for 8-10 hours, placing steel into deionized water for flushing after the nitriding treatment is finished, removing a surface catalyst layer to obtain high corrosion resistant stainless steel, and simultaneously performing carbon dioxide impact on flushing liquid and concentration to obtain a catalyst coating;

the preparation method of the rare earth alloy material in the S3 comprises the following steps:

i: dissolving an aluminum alloy ingot in a high-temperature smelting furnace filled with inert protective gas, controlling the temperature of the high-temperature smelting furnace to be increased to 900-1200 ℃ for high-temperature smelting, continuously carrying out slag skimming treatment in the smelting process, and controlling the smelting and slag skimming treatment for 30-35min;

II: introducing rare earth powder with 15-20% of the mass of the aluminum alloy liquid into a high-temperature furnace filled with inert gas, controlling the temperature in the high-temperature furnace to rise to 200-300 ℃, heating the rare earth powder for 15-20min, and introducing the rare earth powder into the aluminum alloy liquid in step I after the rare earth powder is magnetically cooled;

III: stirring an aluminum alloy liquid added with rare earth powder, rapidly cooling the aluminum alloy liquid through a powder metallurgy technology to obtain a powder rare earth alloy, placing the powder rare earth alloy in a magnetic field formed by a coil filled with direct current, carrying out magnetizing treatment, and controlling the magnetizing time to be 15-20min to obtain a rare earth alloy material;

wherein the steel in S4 is electrified and magnetized before being coated with the catalyst coating, and the magnetic force on the surface of the magnetized steel is controlled to be 0.3-0.5N;

the rare earth alloy is rare earth powder prepared by mixing LaFe 11 Si 2, ceFe 11 Ti and PrFe 4 Al 8 which are rare earth compound magnetic materials according to a ratio of 1:1:1.

2. The method for preparing the high corrosion resistant stainless steel according to claim 1, wherein the method comprises the following steps: wherein the clay in S4 is modified clay prepared from montmorillonite powder and gum arabic according to a ratio of 3:1; the montmorillonite powder is montmorillonite powder clay with a diameter of less than 0.005 mm.

3. The method for preparing the high corrosion resistant stainless steel according to claim 2, wherein the method comprises the following steps: the clay also contains alkaline particles with 15-18% of total mass of sodium bicarbonate and sodium carbonate mixed according to a ratio of 5:1.

4. The method for preparing the high corrosion resistant stainless steel according to claim 1, wherein the method comprises the following steps: wherein the concentration in S5 is carried out by adopting a low-temperature drying technology, and the drying temperature is controlled to be maintained at 5-8 ℃.

5. A highly corrosion resistant stainless steel, characterized by: the high corrosion resistant stainless steel is suitable for the preparation method of the high corrosion resistant stainless steel according to any one of the claims 1 to 4; the high corrosion resistance stainless steel comprises the following elements in proportion:

0.03-0.05% of Mn, 0.01-0.015% of Cr, 0.08-0.1% of Ti, 0.15-0.2% of Nb, 0.1-0.3% of S, 0.2-0.4% of Ni and the balance of Fe.

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