Salt-fog-resistant steel material, preparation method and application thereof

Abstract

The application provides a salt mist resistant steel material, a preparation method and application thereof. The salt mist resistant steel material comprises, from inside to outside, an alloy base, a permeation layer and an anticorrosive coating layer; the alloy base comprises an Fe element; the permeation layer comprises Fe, N and O elements; and the anticorrosive coating layer covers at least a surface of the permeation layer. The steel material has high strength and salt mist resistance, the bonding force between the coating layer and the base is good, the thickness of the anticorrosive coating layer is greatly reduced under the anticorrosive requirement of CX grade, the workpiece machinability is effectively improved, and the adverse effects such as poor surface uniformity caused by poor workpiece clamping force and thick coating layer are avoided.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of metal building materials, in particular to a salt mist resistant steel material, a preparation method and application thereof. BACKGROUND

[0002] Steel is the first choice of material for national infrastructure and mechanical equipment production due to its advantages of rich raw materials, good processability, various performance, high strength, economy and practicality. However, the service environment of large steel structures and steel components often has corrosion factors, which easily causes corrosion damage, resulting in huge economic losses and personal safety accidents. Therefore, it is of great necessity to provide long-term, stable and efficient corrosion protection measures for steel.

[0003] At present, in the extreme environment of high humidity and high salinity in coastal areas, offshore platforms, etc., the national standard requires a corrosion protection level of C5 or CX. The neutral salt spray of C5 level is not less than 2000h, and the neutral salt spray of CX level is not less than 4000h. Common steel corrosion prevention treatment prevents steel corrosion by using alloy coating spraying, so that the coating provides protection for steel in seawater, soil and other strong corrosive application environments. Among them, Zn-Al binary alloy coating has a wide range of applications and good corrosion resistance. However, to achieve C5 level corrosion protection, the thickness of the zinc-aluminum coating needs to be between 80 to 120 microns; to meet the CX level corrosion protection requirement, the thickness of the zinc-aluminum coating is as high as 150 microns. Due to the thick coating, the coating and the substrate are prone to peeling, the workpiece has poor bite force, and the coating surface is uneven. SUMMARY

[0004] To solve the above problems, the present application provides a salt mist resistant steel material, a preparation method and application thereof. The steel material has high strength and salt mist resistance, good bonding force between the coating and the substrate, greatly reduces the thickness of the corrosion resistant coating under the condition of meeting the CX level corrosion protection requirement, effectively improves the processability of the workpiece, and avoids the problems of poor bite force of the workpiece and uneven surface caused by thick coating.

[0005] Therefore, the first object of the present application is to provide a salt mist resistant steel material.

[0006] The second object of the present application is to provide a preparation method of a salt mist resistant steel material.

[0007] The third object of the present application is to provide an application of a salt mist resistant steel material.

[0008] To achieve the first object of the present application, the technical scheme of the present application provides a salt mist resistant steel material, which comprises, from inside to outside, an alloy base, a permeation layer and a corrosion resistant coating; the alloy base comprises Fe element; the permeation layer comprises Fe, N and O elements; and the corrosion resistant coating covers at least the surface of the permeation layer.

[0009] Compared with the prior art, the technical scheme has the following technical effects: the salt mist resistant steel material has a composite layered structure of the alloy base, the permeation layer and the corrosion resistant coating; the surface of the alloy base absorbs N element and O element to form the permeation layer which is dense and has excellent corrosion resistance and wear resistance; and the corrosion resistant coating and the permeation layer work together to further improve the corrosion resistance and the interlayer adhesion of the steel material.

[0010] In one technical scheme of the present application, the alloy base comprises, by mass percentage, C: 0.30%-0.35%; Si: 0.60%-0.80%; Mn: 1.00%-1.20%; S: ≤0.03%; P: ≤0.03%; Ni: 0.3%-0.5%; Mo: 0.05%-0.10%; V: 0.03%-0.05%; O: ≤20ppm; N: ≤30ppm; and the balance of Fe and inevitable impurities.

[0011] Further, the alloy base comprises, by mass percentage, C: 0.30%-0.32%; Si: 0.60%-0.70%; Mn: 1.00%-1.10%; S: ≤0.02%; P: ≤0.02%; Ni: 0.3%-0.4%; Mo: 0.05%-0.10%; V: 0.03%-0.04%; O: ≤20ppm; N: ≤30ppm; and the balance of Fe and inevitable impurities.

[0012] Compared with the prior art, the technical effects reached by adopting the technical scheme are as follows: the alloy base formula design aims to realize excellent mechanical properties, corrosion resistance and processing performance by precisely controlling the chemical composition and impurity level, and the cost and production feasibility are considered, and the corrosion-resistant coating further improves the surface performance of the salt mist resistant steel. The carbon content is between 0.30%-0.35%, which can ensure that the steel has sufficient strength and hardness, while maintaining a certain toughness; the silicon content is between 0.60%-0.80%, which helps to improve the elasticity and wear resistance of the steel; the manganese content is between 1.00%-1.20%, which helps to improve the strength, hardness and hardenability of the steel; the addition of appropriate Ni elements and Mo elements can significantly improve the corrosion resistance, weather resistance and stability of the steel; the addition of a small amount of V elements helps to refine the grains and further improve the strength and corrosion resistance of the material; the content of sulfur and phosphorus is strictly controlled to be ≤0.03%, which helps to reduce the material embrittlement and improve the overall quality of the steel; the content of oxygen and nitrogen is controlled to be less than 20ppm and 30ppm respectively, which helps to avoid the formation of bubbles and inclusions, and ensures the cleanliness and consistency of the material; the formula design of the alloy base considers the convenience of processing, ensures that the material can be processed by conventional metal processing technology without losing its performance, and provides the best performance under the premise of controllable cost.

[0013] In one technical scheme of the present application, the corrosion-resistant coating is Cu(OH)2, SiC composite material and Zn-Al corrosion-resistant coating.

[0014] Compared with the prior art, the technical effects reached by adopting the technical scheme are as follows: the copper hydroxide in the corrosion-resistant coating can effectively inhibit the adhesion and growth of organisms, thereby slowing down the corrosion of the organisms to the material; the SiC composite material has excellent mechanical properties and chemical stability, which not only improves the hardness and wear resistance of the coating, but also significantly improves the corrosion resistance of the base; zinc has a low electrode potential and can be sacrificial anode protection, that is, zinc will corrode preferentially to the steel base, thereby protecting the base from corrosion, and aluminum forms a dense aluminum oxide film on its surface, which can effectively isolate the corrosion medium and prolong the service life of the coating, and the tight accumulation layer formed by the Zn-Al coating on the surface of the alloy base can effectively block the direct contact of corrosion media such as water and oxygen with the base, thereby slowing down the corrosion process.

[0015] In one technical scheme of the present application, the thickness of the corrosion-resistant coating is 3-5 microns.

[0016] Compared with the prior art, the technical effects achieved by the technical scheme are as follows: the thickness of the anticorrosive coating is controlled to achieve the best anticorrosion effect and economy. When the coating thickness is less than 3 microns, the anticorrosion effect is poor; when the coating thickness is greater than 5 microns, the coating is prone to peeling off, and the cost is high. The appropriate coating thickness can ensure that the coating provides sufficient isolation and protection in the corrosion environment, thereby prolonging the service life of the metal substrate.

[0017] To achieve the second object of the present application, the technical scheme of the present application provides a preparation method of a salt mist resistant steel material, comprising: S100, subjecting an alloy base body to nitrocarburizing treatment to obtain a steel material blank; S200, applying an anticorrosive coating on any surface of the steel material blank to obtain a salt mist resistant steel material; wherein the steel material blank is an alloy structure in which a permeation layer covers at least a surface of the alloy base body.

[0018] Compared with the prior art, the technical effects achieved by the technical scheme are as follows: the salt mist resistant steel material of the present application absorbs N element and O element on the surface of the alloy base body through nitrocarburizing treatment of the alloy base body to form a dense permeation layer, thereby significantly improving the hardness and surface strength of the material, and the permeation layer can effectively isolate moisture and salt; then an anticorrosive coating is applied on any surface of the steel material blank to form a salt mist resistant steel material with a composite layered structure of alloy base body, permeation layer and anticorrosive coating. The preparation method of the salt mist resistant steel material of the present application is simple in process, saves anticorrosive coating resources, effectively reduces the production cost of high anticorrosion grade workpieces, and has great significance for the wide application of steel materials.

[0019] In one technical scheme of the present application, S100 specifically comprises: S110, subjecting an alloy raw material to quenching treatment in a protective atmosphere to obtain an alloy blank; S120, subjecting the alloy blank to tempering treatment in a controllable atmosphere to obtain an alloy base body; S130, subjecting the alloy base body to nitrocarburizing treatment in a controllable atmosphere to obtain a steel material blank.

[0020] Compared with the prior art, the technical effects achieved by the technical scheme are as follows: the preparation of the alloy raw material is carried out according to the alloy base body raw material ratio of the technical scheme of the present application. In the preparation process of the salt mist resistant steel material, hydrogen absorption phenomenon exists during quenching heating, and the preparation method of the salt mist resistant steel material of the present application can effectively dehydrogenate through the tempering process, basically maintain the hydrogen content level of the blank, and effectively avoid the hydrogen embrittlement phenomenon; the controllable atmosphere nitrocarburizing treatment utilizes the chemical reaction of gaseous reactants on the solid surface to generate solid deposits to form a dense permeation layer as the temperature rises, which helps to increase the alloy strength, hardness and salt mist resistance, and effectively isolates moisture and salt, which is of great significance for the corrosion protection of marine steel materials.

[0021] In one technical solution of the present application, in S110, the temperature of the quenching treatment is 850-870 DEG C; and / or in S110, the holding time of the quenching treatment is 20-30 min.

[0022] Further, the protective atmosphere is at least one of inert gas.

[0023] Compared with the prior art, the technical effects achieved by adopting the technical solution are as follows: the present application controls the protective atmosphere, temperature and time of the quenching treatment, which can effectively improve the overall performance of the steel after quenching. The temperature of the quenching treatment changes the microstructure of the steel, so that the steel reaches the ideal hardness and uniform organization. Too high heating temperature may lead to coarse grains, thereby reducing the toughness and impact strength of the material. Too small heating temperature affects the formation degree of the metallographic structure and the uniformity of the composition. The protective atmosphere of the quenching treatment can prevent oxidation and decarburization, maintain the surface quality of the steel, and also reduce the evaporation of alloying elements, ensuring the stability of the chemical composition and performance of the steel. The length of the time of the quenching treatment determines the uniformity of the distribution of carbon and other alloying elements in the metallographic structure. Insufficient holding time will lead to uneven composition distribution, affecting the subsequent quenching effect. Too long holding time may lead to surface decarburization, which will reduce the hardness and wear resistance of the steel surface. Long holding time may also lead to the growth of the metallographic structure grains, affecting the performance of the steel after quenching.

[0024] In one technical solution of the present application, in S120, the controllable atmosphere is water vapor, air and ammonia, and the water vapor, air and ammonia are in a volume ratio of (1-2):(3-7):(2-3); and / or in S120, the temperature of the tempering treatment is 550-600 DEG C; and / or in S120, the time of the tempering treatment is 40-80 min.

[0025] Compared with the prior art, the technical effects achieved by adopting the technical solution are as follows: the present application precisely controls the controllable atmosphere, temperature and time of the tempering treatment, prevents oxidation of the alloy matrix, effectively removes hydrogen, significantly improves the toughness and mechanical properties of the material, reduces internal stress, and thus ensures the reliability and stability of the salt spray resistant steel in harsh environments.

[0026] In one technical solution of the present application, in S130, the temperature of the nitriding and oxidizing treatment is 600-650 DEG C; and / or in S130, the time of the nitriding and oxidizing treatment is 40-80 min.

[0027] Compared with the prior art, the technical effects reached by adopting the technical scheme are as follows: by controlling the amount of N element and O element absorbed by the surface of the alloy base through the controllable atmosphere, temperature and time of the nitro-oxidation treatment, the thickness of the moderate permeation layer and the surface quality are formed, so that the hardness, wear resistance and corrosion resistance of the material are improved, and the bonding force with the corrosion-resistant coating is improved.

[0028] To achieve the third object of the present application, the technical scheme of the present application provides an application of the salt-fog-resistant steel material, and the salt-fog-resistant steel material obtained by any of the above preparation methods is used in a scaffold structural member.

[0029] Compared with the prior art, the technical effects reached by adopting the technical scheme are as follows: the scaffold structural member of the present application comprises the salt-fog-resistant steel material or the preparation method of any of the technical schemes of the present application, and thus has all the beneficial effects of the salt-fog-resistant steel material or the preparation method of any of the technical schemes of the present application, which will not be described here. BRIEF DESCRIPTION OF DRAWINGS

[0030] Figure 1 The metallographic structure diagram of the salt-fog-resistant steel material provided by the first embodiment of the present application;

[0031] The reference signs are explained as follows:

[0032] 100-alloy base; 200-permeation layer; 300-corrosion-resistant coating. DETAILED DESCRIPTION

[0033] To make the above objects, features and advantages of the present application more obvious and easy to understand, the specific embodiments of the present application are described in detail below with reference to the drawings. It should be noted that the embodiments of the present application and the features in the embodiments can be combined with each other without conflict. In the following description, a large number of specific details are set forth in order to facilitate a full understanding of the present application, however, the present application can also be implemented in other ways different from those described herein, therefore, the protection scope of the present application is not limited by the specific embodiments disclosed below.

[0034] The technical scheme of some embodiments of the present application is described below with reference to Figure 1

[0035] With reference to Figure 1 It is shown that the embodiments of the present application provide a salt-fog-resistant steel material, which comprises, from inside to outside, an alloy base 100, a permeation layer 200 and a corrosion-resistant coating 300; the alloy base 100 comprises Fe element; the permeation layer 200 comprises Fe, N and O elements; and the corrosion-resistant coating 300 covers at least the surface of the permeation layer.

[0036] Figure 1 ​The metallographic structure diagram of the salt mist resistant steel material provided in the first embodiment of the present application is shown in the figure, the dark part at the top of the figure is the anticorrosive coating 100, the middle part is the transition layer, which is the permeation layer 200, and the uniform part at the bottom of the figure is the alloy matrix 300, wherein the side of the permeation layer 200 close to the anticorrosive coating 300 is Fe-N-O compound, and the side of the permeation layer 200 close to the alloy matrix 100 is the diffusion of Fe (N, O).

[0037] The embodiment of the present application provides a preparation method of a salt mist resistant steel material, which comprises the following steps: S100, subjecting an alloy matrix to nitroxycarburizing treatment to obtain a steel material blank; and S200, applying anticorrosive paint on any surface of the steel material blank to obtain the salt mist resistant steel material; wherein the steel material blank is an alloy structure in which a permeation layer covers at least a surface of an alloy matrix.

[0038] In an embodiment of the present application, S100 specifically comprises the following steps: S110, subjecting an alloy raw material to quenching treatment in a protective atmosphere to obtain an alloy blank; S120, subjecting the alloy blank to tempering treatment in a controllable atmosphere to obtain an alloy matrix; and S130, subjecting the alloy matrix to nitroxycarburizing treatment in the controllable atmosphere to obtain the steel material blank.

[0039] For example, the temperature of the controllable atmosphere is 400 DEG C.

[0040] In an embodiment of the present application, when the anticorrosive coating of the salt mist resistant steel material comprises SiC composite material, in S200, the preparation method of the paint comprises the following steps: uniformly mixing SiC, silane coupling agent and silicone resin, treating the mixture in an inert gas atmosphere at 800 DEG C-900 DEG C for 15 min-30 min to obtain the SiC composite material.

[0041] For example, the silane coupling agent is modified aminosilane coupling agent, and the silicone resin is polymethyl silicone resin.

[0042] For example, the adding amount of SiC, silane coupling agent and silicone resin is 1g-5g SiC: 5mL-25mL silane coupling agent: 1.25mol silicone resin.

[0043] The SiC composite material coating of the present application not only has the protection function of ordinary organic coating, but also can make the whole salt mist resistant steel material maintain its performance for a long time in harsh environment due to the high stability and corrosion resistance of SiC. SiC itself has excellent wear resistance, high temperature resistance and corrosion resistance, and in the anticorrosive coating of the salt mist resistant steel material, SiC provides a solid protective layer to effectively block the invasion of external corrosive medium; the silane coupling agent improves the bonding force between SiC and silicone resin, and improves the overall stability and adhesion of the coating; and the silicone resin as the binder of the paint provides the basic forming properties of the coating and endows the coating with good elasticity and chemical resistance.

[0044] In one embodiment of the present application, S110 specifically comprises: quenching the alloy blank, water cooling to 300 DEG C, and then air cooling to room temperature, and then sequentially performing shot peening treatment and tempering treatment in a controllable atmosphere, and air cooling to room temperature.

[0045] Water cooling is a key step in the quenching process. By rapidly cooling the high-temperature alloy blank, the effect of solid solution treatment is achieved, that is, the strengthening phase in the alloy is fully dissolved to form a supersaturated solid solution, thereby preparing for subsequent aging and precipitation hardening. Water cooling to 300 DEG C can effectively control the cooling speed of the alloy, prevent deformation or cracking of the alloy due to excessive cooling speed, and also ensure the mechanical properties and hardness of the alloy. After water cooling to 300 DEG C, the alloy blank needs to be slowly cooled to room temperature by air cooling. This step aims to reduce the thermal stress inside the alloy, avoid residual stress caused by rapid cooling, and promote the precipitation and transformation of certain phases in the alloy. The air cooling process helps to stabilize the microstructure of the alloy, reduce internal defects, and improve the toughness and fatigue life of the alloy. Shot peening is a surface strengthening process. By high-speed jetting of shot particles to impact the alloy surface, plastic deformation of the surface is generated, a compressive stress layer is formed, the hardness and fatigue strength of the alloy surface can be effectively improved, the surface oxide scale and small defects can be removed, and the introduced compressive stress helps to offset the tensile stress caused by external load, thereby improving the fatigue resistance of the alloy.

[0046] The embodiment of the present application provides an application of the salt mist resistant steel material. The salt mist resistant steel material obtained by any of the above preparation methods is used in a scaffold structural member.

[0047] For example, the salt mist resistant steel material can be in the shape of a scaffold structural member, and can include at least one of a steel plate, a nut, a screw, a connecting piece, a steel pipe, and a plug.

[0048] For example, the salt mist resistant steel material can also be applied to fasteners, automobile parts, and highway guardrail accessories.

[0049] The scaffold structural member of the present embodiment includes the salt mist resistant steel material or the preparation method of any of the embodiments of the present application, and thus has all the beneficial effects of the salt mist resistant steel material or the preparation method of any of the embodiments of the present application, which will not be repeated here.

[0050]

Embodiment 1

[0051] The present embodiment provides a salt mist resistant steel material and a preparation method thereof, which comprises:

[0052] S100, the alloy base material according to the percentage of quality includes: carbon: 0.30%; silicon: 0.60%; manganese: 1.00%; sulfur: 0.03%; phosphorus: 0.03%; Ni: 0.3%; Mo: 0.05%; V: 0.05%; O: 20ppm; N: 30ppm; the balance is Fe and inevitable impurities, the alloy blank is prepared, the alloy blank is quenched in a protective atmosphere, and is sequentially subjected to tempering treatment and nitroxenation treatment in a controllable atmosphere, the thickness of the permeated layer is 2μm, and the steel blank is obtained;

[0053] S200, the alloy base material is coated with a coating material mixed by copper hydroxide and SiC composite material at a mass ratio of 1:1 on any surface of the alloy base material, the thickness of the corrosion-resistant coating is controlled to be 3μm, and the salt spray resistant steel is obtained after drying treatment at 300℃ for 30min after coating.

[0054] Wherein, the quenching heating temperature is 850℃, the holding time is 20min, the water cooling is to 300℃, the air cooling is to room temperature, and then the surface is subjected to shot blasting treatment and tempering treatment, the tempering treatment temperature is 600℃, the tempering treatment time is 60min, the controllable atmosphere is water vapor: air: ammonia = 1:3:2 by volume ratio; the nitroxenation treatment temperature is 600℃, and the holding time is 40min.

[0055]

Example 2

[0056] The embodiment provides a salt spray resistant steel, and specifically refers to example 1, and the difference from example 1 is that in S100, the alloy base material according to the percentage of quality includes: carbon: 0.32%; silicon: 0.70%; manganese: 1.10%; sulfur: 0.02%; phosphorus: 0.03%; Ni: 0.4%; Mo: 0.08%; V: 0.04%; O: 20ppm; N: 30ppm; the balance is Fe and inevitable impurities; the controllable atmosphere of nitroxenation treatment is water vapor: air: ammonia = 1:7:3 by volume ratio; the nitroxenation treatment temperature is 600℃, the holding time is 80min, and the thickness of the permeated layer is 60μm.

[0057]

Example 3

[0058] The embodiment provides a salt mist resistant steel material, and the difference between the embodiment and the embodiment 1 is that in the S100, the alloy base material comprises, according to the mass percentage: carbon: 0.35%; silicon: 0.80%; manganese: 1.20%; sulfur: 0.03%; phosphorus: 0.03%; Ni: 0.5%; Mo: 0.10%; V: 0.05%; O: 10ppm; N: 20ppm; the balance is Fe and inevitable impurities; the controllable atmosphere of the nitriding and oxidizing treatment is water vapor: air: ammonia gas = 2:4:2 in volume ratio; the temperature of the nitriding and oxidizing treatment is 550 DEG C, the holding time is 60min, and the thickness of the permeated layer is 30um.

[0059] Embodiment 4

[0060] The embodiment provides a salt mist resistant steel material, and the difference between the embodiment and the embodiment 1 is that the controllable atmosphere is water vapor: air: ammonia gas = 2:5:2 in volume ratio; in the S200, the copper hydroxide and the SiC composite material are mixed according to the mass ratio of 1:2.

[0061] Embodiment 5

[0062] The embodiment provides a salt mist resistant steel material, and the difference between the embodiment and the embodiment 1 is that the controllable atmosphere is water vapor: air: ammonia gas = 1:5:2 in volume ratio; in the S200, the copper hydroxide and the SiC composite material are mixed according to the mass ratio of 1:2, and the thickness of the corrosion-resistant coating is controlled to be 4um.

[0063] Embodiment 6

[0064] The embodiment provides a salt mist resistant steel material, and the difference between the embodiment and the embodiment 1 is that the controllable atmosphere is water vapor: air: ammonia gas = 2:7:2 in volume ratio; in the S200, the copper hydroxide and the SiC composite material are mixed according to the mass ratio of 1:2, and the thickness of the corrosion-resistant coating is controlled to be 5um.

[0065] Embodiment 7

[0066] The embodiment provides a salt mist resistant steel material, and the difference between the embodiment and the embodiment 1 is that in the S200, the coating is Zn-Al paint.

[0067] Embodiment 8

[0068] The embodiment provides a salt mist resistant steel material, and the difference between the embodiment and the embodiment 1 is that in the S200, the coating is Zn-Al paint.

[0069] Embodiment 9

[0070] The embodiment provides a salt mist resistant steel material, with reference to the embodiment 7, and the difference from the embodiment 7 is that in S100, the alloy base is 42CrMo steel.

[0071] Embodiment 10

[0072] The embodiment provides a salt mist resistant steel material, with reference to the embodiment 7, and the difference from the embodiment 7 is that in S100, the alloy base is 42CrMo steel.

[0073] Embodiment 11

[0074] The embodiment provides a salt mist resistant steel material, with reference to the embodiment 1, and the difference from the embodiment 1 is that the step S200 is not performed.

[0075] Comparative Example 1

[0076] The embodiment provides a salt mist resistant steel material, with reference to the embodiment 1, and the difference from the embodiment 1 is that the step S200 is not performed.

[0077] Comparative Example 2

[0078] The embodiment provides a salt mist resistant steel material, with reference to the embodiment 8, and the difference from the embodiment 8 is that in S100, the nitrocarburizing treatment is not performed.

[0079] Comparative Example 3

[0080] The embodiment provides a salt mist resistant steel material, with reference to the comparative example 2, and the difference from the comparative example 2 is that in S100, the nitrocarburizing treatment is not performed, and in S200, the thickness of the corrosion resistant coating is 100 microns.

[0081] Comparative Example 4

[0082] The embodiment provides a salt mist resistant steel material, with reference to the comparative example 2, and the difference from the comparative example 2 is that in S200, the thickness of the corrosion resistant coating is 150 microns.

[0083] Comparative Example 5

[0084] The embodiment provides a salt mist resistant steel material, with reference to the embodiment 3, and the difference from the embodiment 3 is that the thickness of the permeation layer is 61 microns.

[0085] Comparative Example 6

[0086] The embodiment provides a salt mist resistant steel material, with reference to the embodiment 3, and the difference from the embodiment 3 is that the thickness of the corrosion resistant coating is 6 microns.

[0087] Performance test, detection method reference: GB / T10125-2012 artificial gas corrosion test-salt spray test; GB / T6461-2002 metal substrate on metal and other inorganic coating layer-after corrosion test of sample and test piece rating.

[0088] Table 1

[0089] Conclusion: In the performance test of Table 1, it can be seen from the comparison of Examples 1-10 and Comparative Examples 1-2 that the surface hardness, hardening layer depth, salt spray resistance time and corrosion resistance grade of the steel material treated by the nitro-oxidation process of the application are significantly improved; Example 11 shows that the salt spray resistant steel material with a penetration layer of the application has good corrosion resistance grade even without corrosion protection, and for the same reason, if the corrosion resistant coating of the salt spray resistant steel material of the application is damaged, it also has a certain corrosion resistance to protect the alloy substrate and reduce losses; in Comparative Examples 3-4, by increasing the thickness of the corrosion resistant coating, a salt spray resistance time of 4000 hours and a certain corrosion resistance grade can also be achieved, but due to the thick corrosion resistant coating, the mechanical properties are not good; by comparing the test data of Examples 1-3 and Comparative Examples 5-6, it can be seen that appropriately increasing the thickness of the penetration layer and the corrosion resistant coating has a positive effect on the surface hardness, hardening layer depth, salt spray resistance time and corrosion resistance grade, but when the thickness of the penetration layer and the corrosion resistant coating is too high, the adhesion of the two is affected, which adversely affects the mechanical properties.

[0090] In the description of the present specification, the description of the terms "one embodiment", "some embodiments", "a specific embodiment" and the like means that the specific features, structures, materials or characteristics described in connection with the embodiment or example are included in at least one embodiment or example of the present application. In the present specification, the illustrative description of the above terms does not necessarily refer to the same embodiment or example. Moreover, the described specific features, structures, materials or characteristics can be combined in any one or more embodiments or examples in a suitable manner.

[0091] In the present specification, the writing manner of "S100" and "S200" and the like is to facilitate the description of the embodiments of the present application, and the present application can also be implemented in other ways different from the description herein, therefore, the protection scope of the present application is not limited by the order of the specific embodiments of the above writing manner.

[0092] Although the present application is disclosed as above, the present application is not limited thereto. Any person skilled in the art can make various changes and modifications without departing from the spirit and scope of the present application, therefore, the protection scope of the present application should be limited by the scope defined in the claims.

Claims

1. A method for producing a salt-fog-resistant steel material, characterized by comprising: The method comprises the following steps: ​ S100, nitriding and oxidizing the alloy base to obtain a steel blank, the steel blank being an alloy structure with a nitriding layer covering at least a surface of the alloy base, the nitriding layer comprising Fe, N and O elements; S200, applying a corrosion-resistant coating on any surface of the steel blank to obtain the salt mist resistant steel, the steel comprising the alloy base, the nitriding layer and the corrosion-resistant coating in sequence from inside to outside, the corrosion-resistant coating covering at least a surface of the nitriding layer; wherein the alloy base comprises, by mass percentage, C: 0.30%-0.35%; Si: 0.60%-0.80%; Mn: 1.00%-1.20%; S: ≤0.03%; P: ≤0.03%; Ni: 0.3%-0.5%; Mo: 0.05%-0.10%; V: 0.03%-0.05%; O: ≤20ppm; N: ≤30ppm; and the balance being Fe and inevitable impurities; The S100 specifically comprises: S110, quenching the alloy raw material in a protective atmosphere to obtain an alloy blank; S120, tempering the alloy blank in a controllable atmosphere to obtain the alloy base; S130, nitriding and oxidizing the alloy base in the controllable atmosphere to obtain the steel blank; In S120, the controllable atmosphere is water vapor, air and ammonia, and the water vapor, air and ammonia are in a volume ratio of (1-2):(3-7):(2-3); In S120, the tempering temperature is 550-600°C; In S120, the tempering time is 40-80 min; In S130, the nitriding and oxidizing temperature is 600-650°C; In S130, the nitriding and oxidizing time is 40-80 min.

2. The method according to claim 1, wherein In S110, the quenching temperature is 850-870°C; and / or In S110, the quenching holding time is 20-30 min.

3. Use of a salt spray resistant steel material, characterized in that The salt mist resistant steel prepared by the method of any one of claims 1-2 is used in a scaffold structure.

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