CN111676478A - A kind of preparation method of corrosion-resistant alloy layer on the surface of GCr15 steel - Google Patents

Abstract

The invention relates to a preparation method of a GCr15 steel surface corrosion-resistant alloy layer, which uses B₄C and Cr powder are taken as coating materials to be coated on the surface of the pretreated GCr15 steel matrix material, and the coating materials are metallurgically bonded with the matrix through laser heating, so that the corrosion-resistant alloy layer is obtained. The GCr15 steel prepared by the method has a smooth surface of the alloying layer, has no defects such as cracks and air holes, and has greatly improved hardness and corrosion resistance compared with a matrix.

Description

A kind of preparation method of corrosion-resistant alloy layer on the surface of GCr15 steel

technical field

The invention belongs to the technical field of material surface modification, in particular to a preparation method of a corrosion-resistant alloy layer on the surface of GCr15 steel.

Background technique

GCrl5 steel is one of the most widely used bearing steels. It has high hardness and wear resistance, and has important applications in high-tech fields such as aerospace, rail transit, and nuclear industry. However, GCr15 steel has poor corrosion resistance. Under harsh environmental conditions, key components of bearings made of GCr15 steel often suffer early fatigue failure due to corrosion, especially when serving in marine equipment, due to the action of corrosive ions such as chloride ions. Short service life. Therefore, improving the corrosion resistance of key components of bearings made of GCr15 steel is of great significance to improve bearing life and reliability.

In order to solve the above problems, researchers have tried to use plasma spraying, heat treatment, ion implantation and other methods to modify the surface of GCr15 steel, which has effectively improved its surface corrosion resistance to a certain extent. In the prior art, the Chinese patent document with the application number of 200710193136.9 reported a kind of ion implantation process for surface strengthening of GCr15 bearing steel balls, selecting nitrogen and titanium two kinds of implantation elements, using the implantation energy of 100keV, first implanting titanium and then implanting nitrogen, The dosage is controlled at 2.0～3.0×10 ¹⁷ Ti+2.0～3.0×10 ¹⁷ N, so as to obtain higher hardness and better wear and corrosion resistance; Chinese patent document with application number 201110317942.9 reported that the surface-modified GCr15 compressor blade and its preparation process, after the overall heat treatment (quenching + low temperature tempering) of GCr15 bearing steel blade, PVD is used to deposit Cr-Al-N film on the surface to improve the wear resistance and corrosion resistance of the blade. However, the above technologies have disadvantages such as complex process, low efficiency, high cost, and inability to perform local strengthening.

Therefore, the present invention provides a method for improving the surface corrosion resistance of GCr15 steel. The method of the invention utilizes a laser to prepare a corrosion-resistant alloy layer on the surface of GCr15 steel. Compared with ion implantation, PVD and other technologies, the method of the present invention has simple operation, high efficiency, easy automatic control, and can realize local strengthening and the like. Therefore, the corrosion resistance of the key components of the bearing made of GCr15 steel can be improved by the method of the present invention.

SUMMARY OF THE INVENTION

In view of the above-mentioned problems existing in the prior art, the purpose of the present invention is to provide a preparation method of a corrosion-resistant alloy layer on the surface of GCr15 steel, improve its corrosion resistance under a certain hardness, and prevent GCr15 steel from being in service in a marine environment. Early failure problems caused by corrosion.

The method for preparing a corrosion-resistant alloy layer on the surface of GCr15 steel is characterized in that the GCr15 steel is used as the base material, and the B ₄ C powder for improving the surface wear resistance of the material and the Cr powder for improving the surface corrosion resistance are The composite coating material is coated on the GCr15 steel, and the composite coating material is alloyed with the base material by laser heating to obtain a corrosion-resistant alloy layer on the surface of the GCr15 steel.

The preparation method of the corrosion-resistant alloy layer on the surface of the GCr15 steel is characterized in that it comprises the following steps:

S1. Grind the surface of the base material GCr15 steel, clean it, dry it, and set it aside for use;

S2. Mix the B ₄ C powder and the Cr powder according to the mass ratio and ball-mill until the mixed powder is uniform to obtain the composite coating powder;

S3. Use a binder to adjust the ball-milled composite coating powder into a uniform paste, coat it on the surface of the base material GCr15 steel, keep the coating thickness uniform, and air dry it naturally to obtain a preset powder layer;

S4. Use a fiber laser to scan the sample, and the composite coating material is laser alloyed on the surface of the base material to obtain a corrosion-resistant alloy layer on the surface of GCr15 steel. The working parameters of the laser scanning include: the laser power is 800-1200W, and the scanning speed is 5~20mm/s, the spot diameter is kept at 4mm, the overlap rate is 30~60%, and argon is blown during the laser beam scanning process, and the gas flow is 15~20L/min.

The method for preparing a corrosion-resistant alloy layer on the surface of GCr15 steel is characterized in that in the composite coating material, the mass percentages of the two components are: B ₄ C powder 0%-12%, Cr powder 88%-100% %, preferably B ₄ C powder 5.88% and Cr powder 94.12%.

The method for preparing a corrosion-resistant alloy layer on the surface of GCr15 steel is characterized in that the particle size of the B ₄ C powder is 90-110 nm, preferably 100 nm; the powder particle size of the Cr powder is 95-105 μm, preferably 100 μm, and the purity is greater than or equal to 100 μm. 99%.

The method for preparing a corrosion-resistant alloy layer on the surface of GCr15 steel is characterized in that in step S3, the binder is epoxy resin, and the quality of the binder and the coating powder of the composite coating is 1-3:5, preferably 2:5.

The method for preparing a corrosion-resistant alloy layer on the surface of GCr15 steel is characterized in that in step S3, the thickness of the resin coating is 0.1-0.3 mm.

The method for preparing a corrosion-resistant alloy layer on the surface of GCr15 steel is characterized in that in step S4, the working parameters of the fiber laser are: the laser power is 800W, the speed is 5mm/s, the lap rate is 60%, and the laser beam scans In the composition of the mass percentage of B ₄ C and Cr in the process, argon gas was blown, and the gas flow rate was 15 L/min.

By adopting the above-mentioned technology, compared with the prior art, the beneficial effects of the present invention are as follows:

The present invention utilizes B ₄ C powder and Cr powder as mixed coating materials, carries out laser alloying on the surface of GCr15 steel, and prepares a corrosion-resistant alloying layer with higher hardness under the process parameters defined in the present invention, which is combined with ion implantation, Compared with PVD and other technologies, the surface of the corrosion _- resistant alloy layer prepared by the method of the present invention is relatively smooth, and the alloy layer and the substrate have metallurgical bonding characteristics. Corrosion-resistant alloy layer, and the B ₄ C powder and Cr powder used in the method of the present invention are low in price, simple in process flow, convenient in operation, and high in efficiency, and can achieve local selective strengthening on the surface of parts, which can avoid GCr15 steel. Early failures caused by corrosion occur during service in marine environments, thereby increasing their service life.

Description of drawings

Figure 1 shows the microstructure and morphology of the laser alloy layer composed of B ₄ C powder 11.1% and Cr powder 88.9% by mass percentage of GCr15 steel surface coating;

Figure 2 shows the hardness distribution curve of the laser alloy layer with the composition of the surface coating mass percentage of GCr15 steel: B ₄ C powder 11.1% and Cr powder 88.9%;

Figure 3 shows the microstructure and morphology of the laser alloy layer with the mass percentage composition of B ₄ C powder 5.88% and Cr powder 94.12% on the surface of GCr15 steel;

Fig. 4 is the hardness distribution curve of the laser alloy layer composed of B ₄ C powder 5.88% and Cr powder 94.12% by mass percentage of GCr15 steel surface coating;

Figure 5 shows the microstructure and morphology of the laser alloy layer with the composition of the surface coating of GCr15 steel with a mass percentage of B ₄ C powder of 1.56% and Cr powder of 98.44%;

Figure 6 is a graph showing the hardness distribution of the laser alloy layer with the mass percentage composition of the surface coating of GCr15 steel: B ₄ C powder 1.56% and Cr powder 98.44%;

Fig. 7 is the microstructure and morphology of the laser alloy layer composed of B ₄ C powder 0% and Cr powder 100% by mass percentage of the surface coating of GCr15 steel;

Fig. 8 is a graph showing the hardness distribution of the laser alloy layer with the mass percentage composition of the surface coating of GCr15 steel: 0% of B ₄ C powder and 100% of Cr powder;

Fig. 9 is the microstructure and morphology of GCr15 steel matrix;

Figure 10 is a comparison diagram of polarization curves of GCr15 steel with different mass ratios and the matrix.

Detailed ways

The present invention will be further described below through specific embodiments, but the protection scope of the present invention is not limited thereto.

Example 1

Taking GCr15 steel as the base material, the mass composition of the used coating material is 11.1% of B ₄ C powder and 88.9% of Cr powder.

1) Grind the surface of the substrate with an angle grinder, clean it with anhydrous ethanol, dry it and set it aside for use;

2) Mix the above mass percentages of B ₄ C and Cr evenly with a ball mill, and use epoxy resin as a binder, with a mass ratio of 2:5 to the composite coating, uniformly coat it on the surface of the base metal, keep the thickness uniform, and let it dry. to be used later;

3) Scan the sample with a continuous laser, the power is 800W, the spot diameter is kept at 4mm, the scanning speed is 5mm/s, and argon gas is blown during the laser beam scanning process to protect the molten pool and the laser lens barrel, and the gas flow rate is 15L/ min.

4) Observing the prepared alloy layer, and performing hardness test and corrosion resistance test (obtain the self-corrosion potential and self-corrosion current density in the polarization curve from the analysis software).

5) Figure 1 shows the microstructure of the sample under the laser process of Example 1. The alloying layer is closely combined with the substrate.

6) Figure 2 shows the microhardness of the Cr alloyed coating on the laser surface. The highest hardness of the alloyed layer is 800HV _0.2 , which is much higher than the hardness of the substrate by 200-250HV _0.2 .

7) The polarization curve of the laser surface alloyed coating and the polarization curve of the substrate are shown in Figure 10. The self-corrosion potential of the substrate is -0.5773V, and the self-corrosion current density is 6.714×10 ^-6 A·cm ^-2 . After laser alloying, the self-corrosion potential shift was -0.5459V, which was 5.44% higher than that of the substrate. The self-corrosion current density decreased to 3.706×10 ^-6 A·cm ^-2 , and the self-corrosion current density decreased by 44.8%. Corrosion resistance is significantly improved after laser alloying.

Example 2

Taking GCr15 steel as the base material, the mass composition of the used coating material is 5.88% of B ₄ C powder and 94.12% of Cr powder.

1) Grind the surface of the substrate with an angle grinder, clean it with anhydrous ethanol, dry it and set it aside for use;

2) Mix the above mass percentages of B ₄ C and Cr evenly with a ball mill, and use epoxy resin as a binder, with a mass ratio of 2:5 to the composite coating, uniformly coat it on the surface of the base metal, keep the thickness uniform, and let it dry. to be used later;

3) Scan the sample with a continuous laser, the power is 800W, the spot diameter is kept at 4mm, the scanning speed is 5mm/s, and argon gas is blown during the laser beam scanning process to protect the molten pool and the laser lens barrel, and the gas flow rate is 15L/ min.

4) Observing the prepared alloy layer, and performing hardness test and corrosion resistance test (obtain the self-corrosion potential and self-corrosion current density in the polarization curve from the analysis software).

5) Figure 3 shows the microstructure of the sample under the laser process of Example 2. The alloying layer is closely combined with the substrate.

6) Figure 4 shows the microhardness of the Cr alloyed coating on the laser surface. The highest hardness of the alloyed layer is 642HV _0.2 , which is much higher than the hardness of the substrate by 200-250HV _0.2 .

7) The polarization curve of the laser surface alloyed coating and the polarization curve of the substrate are shown in Figure 10. The self-corrosion potential of the substrate is -0.5773V, and the self-corrosion current density is 6.714×10 ^-6 A·cm ^-2 . After laser alloying, the self-corrosion potential shift is -0.5378V, which is 6.9% higher than that of the substrate, the self-corrosion current density is reduced to 2.022×10 ^-6 A·cm ^-2 , and the self-corrosion current density is reduced by 70.9%.

Example 3

Taking GCr15 steel as the base material, the mass composition of the used coating material is 1.56% of B ₄ C powder and 98.44% of Cr powder.

1) Grind the surface of the substrate with an angle grinder, clean it with anhydrous ethanol, dry it and set it aside for use;

2) Mix the above mass percentages of B ₄ C and Cr evenly with a ball mill, and use epoxy resin as a binder, with a mass ratio of 2:5 to the composite coating, uniformly coat it on the surface of the base metal, keep the thickness uniform, and let it dry. to be used later;

3) Scan the sample with a continuous laser, the power is 800W, the spot diameter is kept at 4mm, the scanning speed is 5mm/s, and argon gas is blown during the laser beam scanning process to protect the molten pool and the laser lens barrel, and the gas flow rate is 15L/ min.

4) Observing the prepared alloy layer, and performing hardness test and corrosion resistance test (obtain the self-corrosion potential and self-corrosion current density in the polarization curve from the analysis software).

5) Figure 5 shows the microstructure of the sample under the laser process of Example 3. The alloying layer is closely combined with the substrate.

6) Figure 6 shows the microhardness of the Cr alloyed coating on the laser surface. The highest hardness of the alloyed layer is 586HV _0.2 , which is much higher than the hardness of the substrate by 200-250HV _0.2 .

7) The polarization curve of the laser surface alloyed coating and the polarization curve of the substrate are shown in Figure 10. The self-corrosion potential of the substrate is -0.5773V, and the self-corrosion current density is 6.714×10 ^-6 A·cm ^-2 . However, after laser alloying, the self-corrosion potential shift was -0.5675V, which was 1.69% higher than that of the substrate. The self-corrosion current density decreased to 3.022×10 ^-6 A·cm ^-2 , and the self-corrosion current density decreased by 54.9%.

Example 4

Taking GCr15 steel as the base material, the mass composition of the used coating material is 0% of B ₄ C powder and 100% of Cr powder.

1) Grind the surface of the substrate with an angle grinder, clean it with anhydrous ethanol, dry it and set it aside for use;

2) Mix the above mass percentages of B ₄ C and Cr evenly with a ball mill, and use epoxy resin as a binder, with a mass ratio of 2:5 to the composite coating, uniformly coat it on the surface of the base metal, keep the thickness uniform, and let it dry. to be used later;

3) Scan the sample with a continuous laser, the power is 800W, the spot diameter is kept at 4mm, the scanning speed is 5mm/s, argon gas is blown during the laser beam scanning process to protect the molten pool and the laser barrel, and the gas flow rate is 15L/ min.

4) Observing the prepared alloy layer, and performing hardness test and corrosion resistance test (obtain the self-corrosion potential and self-corrosion current density in the polarization curve from the analysis software).

5) Figure 7 shows the microstructure of the sample under the laser process of Example 4. The alloying layer is closely combined with the substrate.

6) Figure 8 shows the microhardness of the Cr alloyed coating on the laser surface. The highest hardness of the alloyed layer is 530HV _0.2 , which is much higher than that of the matrix by 200-250HV _0.2 .

7) The polarization curve of the laser surface alloyed coating and the polarization curve of the substrate are shown in Figure 10. The self-corrosion potential of the substrate is -0.5773V, and the self-corrosion current density is 6.714×10 ^-6 A·cm ^-2 . After alloying, the self-corrosion potential shift is -0.5655V, which is 2.04% higher than that of the substrate, the self-corrosion current density is reduced to 6.510×10 ^-6 A·cm ^-2 , and the self-corrosion current density is reduced by 3.31%.

Claims (7)

1. a preparation method of GCr15 steel surface corrosion-resistant alloy layer, it is characterized in that taking GCr15 steel as matrix material, the B ₄ C powder that is used to improve material surface wear resistance and the Cr powder that improves surface corrosion resistance are composite. The coating material is coated on the GCr15 steel, and the composite coating material is alloyed with the base material by laser heating to obtain a corrosion-resistant alloy layer on the surface of the GCr15 steel. 2. the preparation method of GCr15 steel surface corrosion-resistant alloy layer according to claim 1, is characterized in that comprising the steps: S1. Grind the surface of the base material GCr15 steel, clean it, dry it, and set it aside for use; S2. Mix the B ₄ C powder and the Cr powder according to the mass ratio and ball-mill until the mixed powder is uniform to obtain the composite coating powder; S3. Adjust the ball-milled composite coating powder into a uniform paste with a binder, coat it on the surface of the base material GCr15 steel, keep the coating thickness uniform, and air dry it naturally to obtain a preset powder layer; S4. Use a fiber laser to scan the sample, and the composite coating material is laser alloyed on the surface of the base material to obtain a corrosion-resistant alloy layer on the surface of GCr15 steel. The working parameters of the laser scanning include: the laser power is 800-1200W, and the scanning speed is 5~20mm/s, the spot diameter is kept at 4mm, the overlap rate is 30~60%, and argon is blown during the laser beam scanning process, and the gas flow is 15~20L/min. 3. The preparation method of a corrosion-resistant alloy layer on the surface of GCr15 steel according to claim 1 or 2, characterized in that in the composite coating material, the mass percentages of the two components are: B ₄ C powder 0% to 12% %, 88% to 100% of Cr powder, preferably 5.88% of B ₄ C powder and 94.12% of Cr powder. 4. The preparation method of a corrosion-resistant alloy layer on the surface of GCr15 steel according to claim 1, wherein the particle size of the B ₄ C powder is 90-110 nm, preferably 100 nm; the powder particle size of the Cr powder is 95-105 μm, It is preferably 100 μm, and the purity is ≥99%. 5. the preparation method of a kind of GCr15 steel surface anti-corrosion alloy layer according to claim 1, is characterized in that in step S3, adhesive is epoxy resin, and the quality of adhesive and composite coating coating is 1 -3:5, preferably 2:5. 6 . The method for preparing a corrosion-resistant alloy layer on the surface of GCr15 steel according to claim 1 , wherein in step S3 , the thickness of the resin coating is 0.1-0.3 mm. 7 . 7. the preparation method of a kind of GCr15 steel surface corrosion-resistant alloy layer according to claim 1, is characterized in that in step S4, the working parameter of fiber laser: laser power is 800W, and speed is 5mm/s, and the lap rate is 800W. 60%, the composition of the mass percentage of B ₄ C and Cr in the laser beam scanning process was blown with argon, and the gas flow was 15 L/min.

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