WO2018032887A1 - Steel surface-modified structure formed using zinc-nickel infiltration layer, and method for fabrication thereof - Google Patents

Abstract

Provided are a steel surface-modified structure formed using a zinc-nickel infiltration layer, and a corrosion-resistant alloy structure formed on the surface of a steel matrix; the steel surface-modified structure comprises an alloy deposition layer and a metal diffusion layer, formed sequentially from the surface to the interior; the steel matrix is a low-carbon steel or low-carbon alloy steel, the alloy deposition layer is a zinc-iron compound, and the diffusion layer comprises ferrite, pearlite and a quenched-tempered structure. Also provided is a method for fabricating a steel surface-modified structure formed using a zinc-nickel infiltration layer.

Description

Steel surface modification structure formed by zinc-nickel infiltration layer and preparation method thereof Technical field

The invention relates to a steel modified structure, in particular to a steel surface modification structure with high anti-corrosion performance by using zinc-nickel permeation technology and a preparation method thereof.

Background technique

Steel corrosion has caused huge losses to the world, according to relevant information. The annual steel materials scrapped by corrosion in the world are equivalent to more than 20% of annual production, and the loss value is about 700 billion US dollars. It far exceeds the sum of losses caused by natural disasters such as earthquakes, floods and typhoons. At present, there are a variety of anti-corrosion technologies, which have alleviated the corrosion problem of steel, but still can not meet the demand for anti-corrosion. The corrosion resistance of the anti-corrosion layer prepared by the current anti-corrosion technology cannot meet the requirements of anti-corrosion, and the hardness is relatively low. The workpiece treated by the zinc-nickel permeation technology has high corrosion resistance and high wear resistance and vibration resistance.

Therefore, it is necessary to provide a steel surface modification structure having high corrosion resistance formed by a zinc-nickel nitride layer.

Summary of the invention

In view of the above, it is necessary to provide a steel surface modification structure having high corrosion resistance formed by a zinc-nickel nitride layer.

A steel surface modification structure formed by using a zinc-nickel nitride layer, the steel surface modification structure is a corrosion-resistant alloy structure formed on a surface of a steel substrate, and the steel surface modification structure includes a surface formed from the surface to the inside. An alloy deposit layer, a metal diffusion layer, wherein the steel substrate is a low carbon steel or a low carbon alloy steel, the alloy deposit layer is a zinc iron compound, and the diffusion layer comprises ferrite, pearlite and quenched-tempered structure .

Further, the steel substrate is a non-quenched-tempered steel substrate, and the hardness of the metal diffusion layer is higher than the hardness of the steel substrate, wherein the steel matrix has a micro Vickers hardness of between 150 and 260. The metal diffusion layer has a micro Vickers hardness of between 200 and 400.

Further, the steel substrate is a quenched-tempered steel substrate formed after quenching-tempering, the hardness of the metal diffusion layer is not higher than the hardness of the steel substrate, the metal diffusion layer and the steel The micro Vickers hardness of the matrix is between 240-450.

Further, the pearlite color in the metal diffusion layer is lighter than the pearlite color in the steel matrix after etching for tens of seconds with a solution of 1-5% by volume of nitric acid.

Further, the metal diffusion layer of the surface modification material of the low carbon steel and the low carbon alloy steel is tempered sorbite and/or tempered torsite, and is immersed in a solution of 1-5% by volume of nitric acid. It is still white and bright after tens of seconds.

Further, the alloy deposited layer has a thickness of 60-110 micrometers, and the diffusion layer has a thickness of 30-120 micrometers.

Further, the steel substrate of the surface-modified steel material with high corrosion resistance is low carbon steel or low carbon alloy steel.

A method for preparing a steel surface modification structure with high corrosion resistance formed by using a zinc-nickel layer, comprising the following steps:

S1. Providing a steel substrate of low carbon steel or low carbon alloy steel;

S2, pretreatment of the surface of the steel substrate, the pretreatment comprises degreasing and shot blasting;

S3, configured with modified infiltrant, wherein the composition and mass of the infiltrant are uniformly mixed by the following powder components: Zn powder 15-20%, Ni powder 3-4%, Al powder 2-2.5%, Rare earth 2-3%, ammonium chloride 1-4%, the balance is Al ₂ O ₃ powder;

S4, performing surface modification treatment on the steel substrate, placing the steel substrate obtained in step S2 and the osmotic agent disposed in step S3 together in a closed steel container, and then heating the sealed steel container. The sealed steel container is rotated while being heated, and the infiltrant and the steel substrate are placed in a sealed steel container, and the container is heated while rotating, the rotation speed is 5-10 rpm, and the heating temperature is 370 ° C- 450 ° C;

S5, subsequent cleaning treatment.

DRAWINGS

1 is a schematic view showing the surface metallographic structure of a steel material with high corrosion resistance provided by the present invention;

2 is a metallographic cross-sectional view of the non-quenched-tempered Q235 steel provided by the present invention after surface modification;

3 is a metallographic cross-sectional view of the non-quenched-tempered 20 steel provided by the present invention after surface modification;

4 is a metallographic cross-sectional view of the quenched-tempered 20MnTiB steel provided by the present invention after surface modification;

Figure 5 is a metallographic cross-sectional view of the quenched-tempered 25CrMoV steel provided by the present invention after surface modification treatment;

detailed description

The technical solutions in the embodiments of the present invention are clearly and completely described below. It is obvious that the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without creative efforts are within the scope of the present invention.

The invention provides a special process for surface modification of steel materials with corrosion resistance formed by zinc-nickel permeable layer technology, which comprises the following steps:

S1. Providing a steel substrate of low carbon steel or low carbon alloy steel;

In this step, the steel substrate may be any one of Q235 steel, 20 steel, 20MnTiB steel, and 25CrMoV steel.

S2, pretreatment of the surface of the steel substrate;

In this step, the pretreatment of the surface of the steel substrate includes two processes of alkali washing (or ultrasonic cleaning, or low temperature heating) degreasing and shot blasting.

Alkali-eluting fat: refers to the cleaning of a steel substrate using an alkaline liquid. The main components of the alkaline liquid include alkaline or alkaline salts such as sodium hydroxide, sodium carbonate, sodium phosphate, sodium silicate, and sodium borate. Usually the alkaline liquid is a mixture containing two or more of the above components. In addition, the alkaline liquid also contains a steel chelating agent such as EDTA, sodium citrate or triethanolamine, and an organic additive such as ethylene glycol or ethylene glycol monoethyl ether, which has an effect of helping the alkali lotion to improve the cleaning effect.

Ultrasonic degreasing: Ultrasonic cleaning is the direct and indirect action of liquid and cavitation by the cavitation, acceleration and direct flow of ultrasonic waves in the liquid, so that the dirt layer is dispersed, emulsified and stripped to achieve cleaning purposes. It is necessary to prepare a suitable cleaning agent.

Low-temperature heating degreasing: When the temperature reaches the ignition point of the oil substance, the oil substance will burn, volatilize and carbonize to form ash.

Untreated steel substrates are usually coated with contaminants such as rolling oil, engine oil, powder and dust. If these contaminants are not cleaned, these contaminants are easily carbonized at high temperatures during surface modification. The carbon film not only affects the appearance but also seriously affects the surface modification effect. Degreasing can further remove surface contaminants and lay the foundation for subsequent processing.

Shot blasting refers to the further surface cleaning of the degreased steel substrate by shot blasting. The shot blasting process uses a blasting machine to project steel balls onto the surface of the degreased steel substrate, and the surface of the degreased steel substrate can be removed by a shot blasting process to remove contaminants such as surface rust and scale, thereby making the surface of the steel substrate The roughness and cleanliness achieved are achieved and ready for subsequent processes.

S3, configured with a modified infiltrant;

The surface modifying agent is disposed according to the type of the alloy and the anticorrosive effect that the alloy needs to achieve. The multi-permeation agent is powder-like as a whole, and its composition and composition are as follows; Zn powder 15-20%; Ni powder 3-4%, Al powder 2-2.5%, rare earth 2-3%, ammonium chloride 1~ 4%, the balance is Al ₂ O ₃ powder. The infiltrant can adjust the proportion of its parts according to different steel substrates or different uses.

S4, performing surface modification treatment on the steel substrate;

The steel substrate obtained in step S2 and the osmotic agent disposed in step S3 are placed together in a closed steel container, and then the closed steel container is heated, and the closed steel container is rotated while being heated. Through the heat conduction of the infiltrant, the infiltrant and the steel substrate can be at the same temperature, and at this temperature, the infiltration of the infiltrating steel into the surface of the steel substrate can be achieved to achieve the surface modification of the steel material. In the present invention, the closed steel vessel has a rotational speed of 5-10 rpm, so that the osmotic agent and the steel substrate are uniformly heated, thereby achieving uniform surface modification treatment on the steel substrate, and preparing the obtained Anti-corrosion properties of steel surface modification materials.

The steel substrate may be low carbon steel or low carbon alloy steel or the like.

In this step, the temperature at which the closed steel container is heated is between 370 ° C and 450 ° C. The temperature has an important influence on the surface modification process of steel. As the temperature increases, the diffusion rate of atoms in the infiltration agent to the steel matrix will increase sharply. Depending on the type of steel substrate or the different uses, the heating temperature of the closed steel container and the time of surface modification treatment at this temperature are also different. The surface modification treatment time is between 1-10h.

In this step, the steel substrate is directly mixed with the permeating agent at a normal temperature. The steel substrate and the osmotic agent are implemented in a process of heating the closed steel container.

S5, subsequent cleaning processing;

The steel substrate subjected to the S4 treatment is cooled in a natural state, and the surface of the steel piece is removed and washed with water to further remove the infiltrant powder or other impurities adhering to the surface.

After the steel substrate is subjected to the above steps, the modified steel surface modification material can be obtained. Please refer to FIG. 1 , which is a schematic diagram of the metallographic structure of the surface modified steel material provided by the present invention. The surface-modified steel material includes a deposition layer, a diffusion layer, and a steel matrix in order from the outside to the inside. Wherein the diffusion layer is a transition interval of a side of the steel substrate and the deposition layer near a side of the steel substrate. The surface-modified steel substrate has a micro Vickers hardness hardness of between 150 and 260 without undergoing a quenching-tempering process, and the metal diffusion layer has a micro Vickers hardness of 200- Between 400. After the quenching-tempering process, the steel matrix forms a quenched-tempered structure. The metal diffusion layer and the steel substrate have a micro Vickers hardness of between 260 and 450.

Embodiment 1

Please refer to FIG. 2 and FIG. 3 simultaneously, wherein FIG. 2 is a metallographic cross-sectional view of the non-quenched-tempered Q235 steel provided by the present invention after surface modification; FIG. 3 is a non-quenched-tempered 20 steel provided by the present invention. A metallographic cross-section after surface modification.

In this embodiment, the steel substrate is a low carbon steel. Specifically, the low carbon steel is Q235 steel or 20 steel, and the surface modification process of the two is as follows:

First, the surface of the steel substrate is pretreated, specifically comprising performing alkali elution grease and shot blasting on the steel substrate. The specific steps of the alkali eluting grease and the shot blasting have been described above and will not be described again here.

Then, the modified infiltrant is disposed. In the embodiment, the modified infiltrant is powder-like as a whole, and its composition and composition are as follows: Zn powder 15%, Ni powder 4%, Al powder 2%, rare earth 3%. Ammonium chloride 1%, the balance is Al ₂ O ₃ powder.

Furthermore, the steel substrate is subjected to surface modification treatment. Specifically, the steel substrate and the infiltrant are co-located in a closed steel container, and then the closed steel container is heated, and the sealed steel container is rotated while being heated, through the The heat transfer of the osmotic agent can achieve that the osmotic agent and the steel substrate are at the same temperature, and the surface modification treatment is achieved at the temperature. In the present invention, the closed steel vessel has a rotational speed of 5 rpm so that the osmotic agent and the steel substrate are uniformly heated, thereby effecting surface modification treatment of the steel. The surface modification treatment time was 1 h, the treatment temperature was 420 ° C, and a steel surface modification material having corrosion resistance was prepared.

In this embodiment, the Q235 steel and the 20 steel are not subjected to heat treatment during mixing with the infiltrant. That is, the two are directly mixed at ambient temperature and then co-heated in the steel vessel to complete the surface modification process.

In the present embodiment, the low carbon steel is Q235 steel or 20 steel: the modified steel of the steel base is Q235 steel, and the steel surface modification structure having high corrosion resistance formed on the surface of the steel substrate. The steel surface modification structure comprises two layers of metallographic structure, which are an alloy deposition layer and a metal diffusion layer in order from the surface to the inside. It can be understood that the innermost layer is a steel substrate.

The surface of the modified steel material with steel base of 20 steel also forms two layers of steel surface modification structure. The alloy deposit layer and the metal diffusion layer are in order from the surface to the inside. It can be understood that the innermost layer is also a steel matrix.

In the present embodiment, the steel substrate is subjected to a surface modification treatment in a non-quenched-tempered state. Specifically, when the steel substrate and the infiltrant are mixed, the steel substrate and the infiltrant are mixed at a normal temperature.

At this time, the metal diffusion layer of the steel material can be seen from both FIG. 2 and FIG. 3, in which the color of the pearlite in the metal diffusion layer is lighter than that of the pearlite in the steel matrix. The Vickers hardness of the metal diffusion layers of both is higher than the hardness of the respective steel substrates. The metal diffusion layer has a thickness of 30 to 80 μm.

Embodiment 2

Please refer to FIG. 4 and FIG. 5 at the same time, wherein FIG. 4 is a metallographic cross-sectional view of the quenched-tempered 20MnTiB steel provided by the present invention after surface modification treatment. Fig. 5 is a metallographic cross-sectional view of the quenched-tempered 25CrMoV steel provided by the present invention after surface modification treatment.

In this embodiment, the steel substrate is a low carbon alloy steel, and the low carbon alloy steel is 20MnTiB steel or 25CrMoV steel, and the surface modification process of the low carbon alloy steel is as follows:

The steel substrate is first subjected to a quenching-tempering treatment to form a quenched-tempered structure.

First, the surface of the steel substrate is pretreated, specifically comprising performing alkali elution grease and shot blasting on the steel substrate. The specific steps of the alkali eluting grease and the shot blasting have been described above and will not be described again here.

Then, the multi-osmotic agent is disposed. In the embodiment, the multi-permeation agent is powdered as a whole, and its composition and composition are as follows: Zn powder 20%, Ni powder 3%, Al powder 2.5%, rare earth 2%, chlorine Ammonium 4%, the balance is Al ₂ O ₃ powder.

Furthermore, the steel substrate is subjected to surface modification treatment. Specifically, the steel substrate and the infiltrant are co-located in a closed steel container.

And heating the closed steel container, rotating the closed steel container while heating, and the heat transfer of the infiltrant can achieve the same temperature of the infiltrant and the steel substrate, and The surface modification treatment is carried out at this temperature. In the present invention, the closed steel vessel has a rotational speed of 8 rpm so that the osmotic agent and the steel substrate are uniformly heated, thereby effecting surface modification treatment of the steel substrate. The surface modification treatment time was 10 h, and the treatment temperature was 370 °C.

In the present embodiment, the 20MnTiB steel and the 25CrMoV steel are not subjected to heat treatment during mixing with the infiltrant, that is, directly mixed at ambient temperature, and then heated in the steel vessel to complete the surface modification process.

In this embodiment, the low carbon alloy steel is 20MnTiB steel and 25CrMoV steel.

The surface structure of the surface of 20MnTiB steel and 25CrMoV steel also includes a two-layer structure formed on the surface of 20MnTiB steel and 25CrMoV steel, including alloy deposition layer and metal diffusion layer from surface to interior. It can be understood that the innermost layer For the steel matrix.

The quenched-tempered structure is formed after the steel substrate is subjected to quenching-tempering treatment. Specifically, in the present embodiment, the metal diffusion layer is a quenched-tempered structure, and specifically, the metal diffusion layer is tempered sorbite. In the present embodiment, when the 20MnTiB steel and the 25CrMoV steel are respectively mixed with the multi-permeability agent, they are mixed at a normal temperature.

Please refer to Fig. 4 and Fig. 5 again. At this time, after the steel matrix is 20MnTiB steel and 25CrMoV steel modified diffusion layer is etched in 1-5% nitric acid solution, it can be observed that the metal diffusion layer is still present. The white color is bright, indicating that both are not easily corroded. And the Vickers hardness of the metal diffusion layer is not higher than the hardness of the steel substrate. The thickness of the metal diffusion layer is 80-120 micrometers, and the hardness of the metal diffusion layer of the 20MnTiB steel and the 25CrMoV steel subjected to the surface modification treatment is not higher than the micro Vickers hardness of the steel substrate.

Compared with the prior art, the surface modification structure using the zinc-nickel permeation technology provided by the invention has a good anti-corrosion effect, and the loss due to steel corrosion can be greatly reduced. In addition, the surface protective layer of the material modified by the surface of the zinc-nickel layer has good wear resistance, has good impact resistance, and does not change the original mechanical properties of the product.

The above is only the embodiment of the present invention, and thus does not limit the scope of the patent of the present invention. Any equivalent structure or equivalent process transformation made by using the contents of the specification of the present invention, or directly or indirectly applied to other related technical fields, The same is included in the scope of patent protection of the present invention.

Claims (8)

1.  A steel surface modification structure formed by using a zinc-nickel nitride layer, the steel surface modification structure being a corrosion-resistant alloy structure formed on a surface of a steel substrate, characterized in that the steel surface modification structure includes a surface An alloy deposition layer, a metal diffusion layer formed in sequence internally, wherein the steel substrate is a low carbon steel or a low carbon alloy steel, the alloy deposition layer is a zinc iron compound, and the diffusion layer includes ferrite, pearlite, and Quenching-tempering structure.
2.  The steel surface modification structure formed by using a zinc-nickel nitride layer according to claim 1, wherein the steel substrate is a non-quenched-tempered steel substrate, and the hardness of the metal diffusion layer is higher than the steel substrate Hardness, wherein the steel matrix has a micro Vickers hardness of between 150 and 260, and the metal diffusion layer has a micro Vickers hardness of between 200 and 400.
3. The steel surface modification structure formed by using a zinc-nickel nitride layer according to claim 1, wherein the steel base body is a quenched-tempered steel base body formed after quenching-tempering treatment, the metal diffusion layer The hardness is not higher than the hardness of the steel substrate, and the micro-Vickers hardness of the metal diffusion layer and the steel substrate are between 240 and 450.
4. The steel surface modification structure formed by using a zinc-nickel nitride layer according to claim 2, wherein the pearlite color in the metal diffusion layer after etching for tens of seconds with a solution of 1-5% by volume of nitric acid It is lighter in color than pearlite in the steel matrix.
5.  The steel surface modification structure formed by using a zinc-nickel nitride layer according to claim 3, wherein the metal diffusion layer of the low carbon steel and low carbon alloy steel surface modification material is tempered sorbite and/or Or tempered tortuossite, and after a few ten seconds of immersion in a 1-5% volume fraction of nitric acid, it is still white and bright.
6.  The steel surface modification structure formed by using a zinc-nickel nitride layer according to any one of claims 1 to 5, wherein the alloy deposition layer has a thickness of 60 to 110 μm and the diffusion layer has a thickness of 30 -120 microns.
7. The steel surface modification structure formed by using a zinc-nickel nitride layer according to claim 6, wherein the steel substrate of the surface-modified steel material having high corrosion resistance is low carbon steel or low carbon alloy steel.
8. A method for preparing a steel surface modified structure formed by using a zinc-nickel layer comprises the following steps:

   S1. Providing a steel substrate of low carbon steel or low carbon alloy steel;

   S2, pretreatment of the surface of the steel substrate, the pretreatment comprises degreasing and shot blasting;

   S3, configured with modified infiltrant, wherein the composition and mass of the infiltrant are uniformly mixed by the following powder components: Zn powder 15-20%, Ni powder 3-4%, Al powder 2-2.5%, Rare earth 2-3%, ammonium chloride 1-4%, the balance is Al ₂ O ₃ powder;

   S4, performing surface modification treatment on the steel substrate, placing the steel substrate obtained in step S2 and the osmotic agent disposed in step S3 together in a closed steel container, and then heating the sealed steel container. The sealed steel container is rotated while being heated, and the infiltrant and the steel substrate are placed in a sealed steel container, and the container is heated while rotating, the rotation speed is 5-10 rpm, and the heating temperature is 370 ° C- 450 ° C;

   S5, subsequent cleaning treatment.

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