An Fe2B-reinforced iron-based metal powder for ultra-high-speed laser cladding, its preparation and application

Abstract

The present invention relates to the field of metal materials, and specifically relates to a Fe2B-reinforced iron-based metal powder for ultra-high-speed laser cladding, its preparation and application. The chemical composition and mass percentage of the powder used for ultra-high-speed laser cladding are as follows: C: 0.1-0.4%, Cr: 12-16%, Ni: 1-3%, B: 1.5-5%, Si: 0-1%, and the balance is Fe. The present invention adopts the concept of non-differentiated coating design, and for the first time attempts to use ultra-high-speed laser cladding technology in combination with powders of special components to prepare high-quality coatings without a transition layer. In the process of ultra-high-speed laser cladding, the present invention enhances the friction and wear properties of the iron-based cladding coating by in-situ synthesizing Fe2B intermetallic compounds. The component design of the present invention is reasonable, the preparation process is simple and controllable, and the obtained product has high hardness, low probability of crack generation, corrosion resistance, and is convenient for industrial application.

Description

Technical Field

[0001] The present invention relates to the field of metal materials, and particularly to a Fe2B-reinforced iron-based metal powder for ultra-high-speed laser cladding, its preparation and application. Background Art

[0002] The solubility of B element in α-Fe and γ-Fe is very low. When it exceeds the solubility, high-hardness network borides will precipitate at the grain boundaries of the steel, greatly improving the wear resistance of the steel, but also reducing the toughness of the steel to a certain extent. The most obvious is that cracks are extremely likely to appear. Among various borides, only FeB and Fe2B are stable phases, and the others are metastable phases. FeB has relatively large brittleness and is not suitable for practical applications. Therefore, in actual production, Fe2B has been widely used as an anti-wear phase in steel boronizing and boron-containing wear-resistant cast iron. Borides have high hardness, excellent wear resistance and corrosion resistance, low price, and wide sources, and have broad development prospects in the field of wear-resistant materials.

[0003] According to the currently disclosed information, the introduction of less than 0.3% boron can improve the toughness of steel or cast iron (such as patents 200810104993.1, JP3150334-A, JP93041691-B, CN1884605, CN1189542A). However, the introduction of a large amount of borides, especially on the basis of laser cladding technology, is very likely to cause cracks, thereby affecting the performance of the product. In response to this, people have tried to use a high-speed laser cladding + ultra-high-speed laser cladding process to avoid the generation of cracks as much as possible. Such as patent CN202211039363.7. In this patent, the process used is: using the first coating laser cladding composite powder on the surface of the part and using a high-speed laser cladding method to process the first coating; immediately after the first coating is clad, using the second coating laser cladding composite powder and using an ultra-high-speed laser cladding method to process the second coating. The optimized first coating laser cladding composite powder has the following components: C: ≤0.03wt%, Si: 0.80wt%~1.0wt%, Cr: 16.1wt%~18.6wt%, Ni: 9.8wt%~14.6wt%, Mn: 1.9wt%~2.1wt%, Mo: 2.0wt%~3.0wt%, and the balance is Fe; the second coating laser cladding composite powder has the following components: C: 0.15wt%~0.20wt%, B: 0.70wt%~0.90wt%, Si: 0.70wt%~0.90wt%, Cr: 16wt%~19wt%, Ni: 2.2wt%~3.0wt%, Mn: 0.3wt%~0.5wt%, Mo: 0.95wt%~1.2wt%, and the balance is Fe. Through the differentiated design of the thickness, hardness and material composition of the first coating and the second coating, it can effectively solve the problem of easy cracking of high-hardness corrosion-resistant coatings clad by high-speed laser cladding, and greatly improve the overall protective effect of the coating. Summary of the invention

[0004] In order to further simplify the coating and its preparation process, and to achieve ultra-high-speed laser cladding to prepare a wear-resistant and corrosion-resistant coating that can replace the electroplating coating; the present invention proposes a Fe2B-reinforced iron-based metal powder for ultra-high-speed laser cladding, and provides a preparation method and application of the powder. The composition design of the present invention improves the wear resistance and corrosion resistance of the coating while reducing the cost as much as possible, and is combined with the corresponding preparation process to finally obtain a cladding coating without macro defects such as cracks and holes.

[0005] The present invention adopts the concept of non-differentiated coating design and for the first time attempts to use ultra-high-speed laser cladding technology in combination with powders of special components to produce high-quality coatings that do not require a transition layer.

[0006] The present invention provides an Fe2B-reinforced iron-based metal powder for ultra-high speed laser cladding. The chemical composition and mass percentage of the powder used for ultra-high speed laser cladding are as follows: C: 0.1 - 0.4%, Cr: 12 - 16%, Ni: 1 - 3%, B: 1.5 - 5%, Si: 0 - 1%, and the balance is Fe.

[0007] The present invention provides an Fe2B-reinforced iron-based metal powder for ultra-high speed laser cladding. The powder raw materials used for ultra-high speed laser cladding include Fe-B alloy powder and iron-based metal powder.

[0008] In the present invention, when the B content in the powder used for ultra-high speed laser cladding is greater than 4.5 wt%, cracks are likely to appear in the coating, which will further affect the corrosion resistance of the product. Therefore, as a preferred solution:

[0009] An Fe2B-reinforced iron-based metal powder for ultra-high speed laser cladding according to the present invention, the mass percentage of its B element is 1 - 4%.

[0010] The content of each element and mass percentage of the iron-based metal powder is: C: 0.1 - 0.4%, Cr: 15 - 18%, Ni: 1 - 3%, B: 0 - 1%, Si: 0 - 1%, and the balance is Fe.

[0011] Preferably, the Fe-B alloy powder includes the following components by mass percentage: C: 0.25 - 0.3%, B: 15 - 16%, Si: 0.2 - 0.3%, and the balance is Fe.

[0012] Preferably; an Fe2B-reinforced iron-based metal powder for ultra-high speed laser cladding according to the present invention; in the powder used for ultra-high speed laser cladding, the preferred ranges of the following elements by mass percentage are:

[0013] B: 1.5 - 4%;

[0014] Cr: 13.5 - 16%;

[0015] Ni: 2 - 3%.

[0016] As a further preference; an Fe2B-reinforced iron-based metal powder for ultra-high speed laser cladding according to the present invention; in the powder used for ultra-high speed laser cladding, by mass percentage, B: 1.9 - 4%.

[0017] As a further more preferred; an Fe2B-reinforced iron-based metal powder for ultra-high speed laser cladding according to the present invention; in the powder used for ultra-high speed laser cladding, by mass percentage, B: 2.5 - 3.9%. Of course, 2.8 - 3.85% is also a further preferred range.

[0018] In an alternative scope of implementation, the Fe-B alloy powder has an irregular shape and a particle size distribution range of 38 - 48 μm. In an alternative scope of implementation, the sphericity of the iron-based metal powder is ≥ 90%, and the particle size distribution range is 48 - 75 μm.

[0019] A method for preparing Fe2B-reinforced iron-based metal powder for ultra-high speed laser cladding according to the present invention comprises the following specific steps:

[0020] Step 1: Weigh the iron-based metal powder and the Fe-B alloy powder in proportion, wherein the B element introduced by the Fe-B alloy powder accounts for 1 - 4% of the total mass of the mixed powder, preferably 1 - 3%;

[0021] Step 2: Place the prepared powders together in a ball mill for ball milling. The ball milling time of the mixed powder is 6 - 8 h, and the ball milling speed is 120 - 160 rpm;

[0022] Step 3: Screen the particle size of the ball-milled composite powder, and screen out the powder with a particle size of 38 - 75 μm to obtain the Fe2B-reinforced iron-based metal powder for ultra-high speed laser cladding.

[0023] The present invention also provides an application of the Fe2B-reinforced iron-based metal powder for ultra-high speed laser cladding, which comprises the following specific steps:

[0024] On a clean and dry substrate surface, using the obtained Fe2B-reinforced iron-based metal powder for ultra-high speed laser cladding as raw material; performing coating cladding using an ultra-high speed laser cladding system; obtaining an Fe2B-reinforced iron-based metal coating; the process parameters during the cladding process are: laser defocus amount is +1 mm, laser power is 2000 - 2600 W, laser scanning speed is 12 - 18 m / min, powder feeding speed is 20 - 24 g / min, and the overlap rate between adjacent tracks is 70% - 80%.

[0025] Preferably, the present invention also provides an application of the Fe2B-reinforced iron-based metal powder for ultra-high speed laser cladding, which comprises the following specific steps:

[0026] On a clean and dry substrate surface, using the obtained Fe2B-reinforced iron-based metal powder for ultra-high speed laser cladding as raw material; performing coating cladding using an ultra-high speed laser cladding system; obtaining an Fe2B-reinforced iron-based metal coating; the process parameters during the cladding process are: laser defocus amount is +1 mm, laser power is 2300 - 2600 W, laser scanning speed is 15 - 18 m / min, powder feeding speed is 20 - 24 g / min, and the overlap rate between adjacent tracks is 70% - 75%.

[0027] In order to pursue higher performance and avoid crack generation as much as possible, during industrial application, the laser power is 2300 - 2400W, the laser scanning speed is 15 - 16m / min, the powder feeding speed is 23 - 24g / min, and the overlap rate between tracks is 70% - 72%.

[0028] During industrial application, the surface of the substrate can be machined first; then impurities such as grease are removed; and finally, it is dried and reserved for use after drying.

[0029] The thickness of the obtained coating is 240 - 300μm. The surface roughness of the obtained coating after grinding is R a = 0.7 - 1.2μm. Before grinding, the surface roughness of the obtained coating is R a = 10.4 - 12μm.

[0030] After optimization, for the coating prepared by the process of the present invention, the self - corrosion voltage of the coating is - 0.5V to - 0.575V; and the hardness of the coating is 700 - 900HV 0.2 .

[0031] In the present invention, the introduction of element B is achieved by doping Fe - B alloy, which can avoid the burning loss of B during cladding when added alone, facilitating the formation of Fe2B phase. During the ultra - high - speed laser cladding process, the friction and wear properties of the iron - based cladding coating are enhanced by in - situ synthesizing Fe2B intermetallic compounds. On the premise of ensuring the corrosion resistance of the coating, the hardness of the coating is greatly increased, and a wear - resistant and corrosion - resistant coating reinforced with hard particles is obtained. The obtained coating is metallurgically bonded to the substrate, with a low dilution rate, a low probability of pores and cracks (even cracking can be avoided), and can be used for the surface strengthening and repair of shaft - type parts. Selecting an iron - based powder system with physical properties similar to those of the substrate helps to prepare a defect - free cladding layer and provides the possibility for in - situ synthesizing Fe2B hard phase, greatly reducing the powder raw material cost and thus reducing the production cost.

[0032] The beneficial effects of the present invention are as follows:

[0033] (1) After the Fe2B - enhanced iron - based metal powder designed in the present invention is cladded to form a cladding layer, it has excellent wear - resistant and corrosion - resistant properties. The synergistic effect of the tough matrix and Fe2B hard particles greatly improves the wear - resistant performance of the coating. By controlling the contents of Cr: 13.5 - 16% and Ni: 2 - 3% in the Fe2B - enhanced iron - based metal powder for ultra - high - speed laser cladding, the electrochemical potential of the substrate can be increased, thereby improving the corrosion resistance. And Ni, as an austenite - forming element, will promote martensite transformation in the substrate under the condition of rapid cooling during ultra - high - speed laser cladding, increasing the hardness of the substrate.

[0034] (2) The present invention uses Fe-B alloy powder to add a large amount of appropriate B element, which can not only prevent the burning loss of elemental B under the direct action of laser during the high-speed laser cladding process, but also facilitate the precipitation of Fe2B phase.

[0035] (3) The raw material costs of the Fe2B-reinforced iron-based metal powder designed by the present invention are all relatively low. On the premise of controlling costs as much as possible, the cladding coating still has good wear resistance and corrosion resistance. By using the ultra-high-speed laser cladding process with appropriate parameters, a cladding layer with low surface roughness and no defects such as pores and cracks can be obtained, which can replace electroplating in the surface strengthening and repair of shaft parts.

[0036] (4) The present invention also realizes the introduction of as much B element as possible while avoiding the generation of coating cracks as much as possible. Even when the B content is 2.8 - 2.9%, the coating does not generate cracks. Description of the Drawings

[0037] Figure 1 is the macroscopic view of the ultra-high-speed laser cladding Fe2B-reinforced iron-based coating for Example 3 and Example 4;

[0038] Figure 2 is the cross-sectional micrograph of the ultra-high-speed laser cladding Fe2B-reinforced iron-based coating for Example 4 (magnification: 100X);

[0039] Figure 3 is the cross-sectional micrograph of the ultra-high-speed laser cladding Fe2B-reinforced iron-based coating for Example 4 (magnification: 200X);

[0040] Figure 4 is the curve of the friction coefficient varying with time for Comparative Example 1, Example 3, Example 4, Example 7 and the substrate 45 steel. Detailed Embodiments

[0041] Example 1

[0042] Weigh a certain amount of iron-based metal powder. The mass percentages of each element in the iron-based powder are: C: 0.4%, Cr: 16%, Ni: 2%, B: 1%, Si: 1%, and the balance is Fe.

[0043] According to the weighed amount of FeB alloy powder, the introduced B element accounts for 1% of the total mass of the mixed powder. The element composition and mass percentage content of the FeB alloy powder are: C: 0.29%, B: 15.8%, Si: 0.25%, and the balance is Fe.

[0044] The sphericity of the iron-based metal powder ≥ 90%, and the particle size distribution range is 48 - 75 μm. The FeB alloy powder is irregular in shape, and the particle size distribution range is 38 - 48 μm.

[0045] Put the weighed mixed powder into a planetary ball mill. The ball-to-powder ratio is selected as 2:1, the ball milling time is 6 h, and the ball milling speed is 120 rpm.

[0046] The mass percentages of the elements in the mixed powder are: C: 0.393%, Cr: 14.987%, Ni: 1.873%, B: 1.937%, Si: 0.953%, and the balance is Fe.

[0047] Screen the ball-milled composite powder to select the composite powder with a particle size range of 38 - 75 μm.

[0048] Use the above Fe2B-reinforced iron-based metal powder for ultra-high-speed laser cladding to strengthen and repair the surface of the substrate. The specific steps are as follows:

[0049] Machine the surface of the substrate to remove the surface oxide film;

[0050] Wipe the surface of the substrate with anhydrous ethanol to remove the residual surface grease after machining;

[0051] Dry the powder, control the temperature at 100 °C for 1 h;

[0052] Perform ultra-high-speed laser cladding. The cladding process parameters are: laser defocus amount is +1 mm, laser power is 2600 W, laser scanning speed is 18 m / min, powder feeding speed is 20 g / min, and the overlap rate between tracks is 70%.

[0053] The thickness of the obtained coating is 255 μm.

[0054] Use a micro-Vickers hardness tester to measure the hardness of the coating, and the average hardness can reach 700 HV 0.2 . Measure the self-corrosion voltage as -0.53 V and the self-corrosion current as 6.135 μA using an electrochemical workstation.

[0055] The Vickers hardness of the substrate 45 steel is 320 HV 0.2 , the self-corrosion voltage is -0.612 V, and the self-corrosion current is 26.749 μA. The coating performance is significantly better than that of the substrate.

[0056] Metallographic microscopic observation shows that there are no macroscopic cracks, pores and other defects in the coating. The surface quality of the product obtained in this example is good. After slight grinding, it can be comparable to the surface quality of electroplated products, but the hardness of the product still needs to be improved. The surface roughness of the coating after slight grinding is R a = 1.0 μm. Before grinding, the roughness of the coating is R a = 10.8 μm.

[0057] Example 2

[0058] Weigh a certain amount of iron-based metal powder. The mass percentages of each element in the iron-based powder are: C: 0.4%, Cr: 16%, Ni: 2%, B: 1%, Si: 1%, and the balance is Fe.

[0059] According to weighing a certain amount of FeB alloy powder, the introduced B element accounts for 4% of the total mass of the mixed powder. The element composition and mass percentage content of the FeB alloy powder are: C: 0.29%, B: 15.8%, Si: 0.25%, and the balance is Fe.

[0060] The sphericity of the iron-based metal powder is ≥90%, and the particle size distribution range is 48 - 75 μm. The FeB alloy powder is irregular in shape, and the particle size distribution range is 38 - 48 μm.

[0061] Put the weighed mixed powder into a planetary ball mill. The ball-to-powder ratio is selected as 2:1, the ball milling time is 6 h, and the ball milling speed is 120 rpm.

[0062] Screen the ball-milled composite powder, and select the composite powder with a particle size range of 38 - 75 μm.

[0063] The mass percentages of each element in the mixed powder are: C: 0.372%, Cr: 11.95%, Ni: 1.494%, B: 4.747%, Si: 0.810%, and the balance is Fe.

[0064] Use the above Fe₂B-reinforced iron-based metal powder for ultra-high-speed laser cladding to strengthen and repair the surface of the substrate. The specific steps are as follows:

[0065] Machine the surface of the substrate to remove the surface oxide film;

[0066] Wipe the surface of the substrate with anhydrous ethanol to remove the surface grease remaining after machining;

[0067] Dry the powder, control the temperature at 100 °C, and the time at 1 h;

[0068] Carry out ultra-high-speed laser cladding. The cladding process parameters are: laser defocus amount is +1 mm, laser power is 2600 W, laser scanning speed is 15 m / min, powder feeding speed is 20 g / min, and the overlap rate between tracks is 70%.

[0069] The thickness of the obtained coating is 300 μm.

[0070] Use a micro-Vickers hardness tester to detect the hardness of the coating, and the average hardness can reach 1200 HV 0.2 . The self-corrosion voltage measured by an electrochemical workstation is -0.647 V, and the self-corrosion current is 4.784 μA.

[0071] The Vickers hardness of the substrate 45 steel is 320 HV0.2 The self-corrosion voltage is -0.612 V and the self-corrosion current is 26.749 μA. The hardness value of the coating is significantly greater than that of the substrate. Although the corrosion resistance decreases to some extent due to the presence of cracks, it is still better than that of the substrate.

[0072] Metallographic microscopy observation reveals that there are a large number of cracks in the coating. The hardness of the product obtained in this example is extremely high, but

[0073] the surface quality is basically unqualified. Under the condition of slight grinding in Example 1, the surface roughness of the coating after grinding is R a = 3.5 μm. Before grinding, the roughness of the coating is R a = 11.8 μm.

[0074] Comparative Example 1

[0075] Weigh a certain amount of iron-based metal powder. The mass percentages of each element in the iron-based powder are: C: 0.2%, Cr: 17%, Ni: 2.5%, B: 1%, Si: 0.6%, and the balance is Fe.

[0076] Use the above iron-based metal powder for ultra-high-speed laser cladding to strengthen and repair the surface of the substrate. The specific steps are as follows:

[0077] Machine-process the surface of the substrate to remove the surface oxide film;

[0078] Wipe the surface of the substrate with anhydrous ethanol to remove the residual surface grease after machining;

[0079] Dry the powder, control the temperature at 100 °C for 1 h;

[0080] Conduct ultra-high-speed laser cladding. The cladding process parameters are: laser defocus amount is +1 mm, laser power is 2300 W, laser scanning speed is 15 m / min, powder feeding speed is 20 g / min, and the overlap rate between tracks is 70%.

[0081] The thickness of the obtained coating is 240 μm.

[0082] Use a micro-Vickers hardness tester to measure the hardness of the coating, and the average hardness reaches 680 HV 0.2 . Use an electrochemical workstation to measure the self-corrosion voltage as -0.459 V and the self-corrosion current as 4.853 μA.

[0083] Conduct a reciprocating friction and wear experiment on the surface of the coating with a chromium steel ball. The load is 30 N, the friction sliding distance is 10 mm, and the time is 40 min. Its friction coefficient is as Figure 4 shown, and the volumetric wear amount is 7.592×10 -3 mm 3The volume wear of the substrate 45 steel is 5.552×10 -2 mm 3 The volume wear of the coating is 13.67% of the volume wear of the substrate.

[0084] Metallographic microscopic observation shows that there are no macroscopic cracks, pores and other defects in the coating. The hardness of the product obtained in this comparative example still needs to be improved.

[0085] Example 3

[0086] Weigh a certain amount of iron-based metal powder. The mass percentages of each element in the iron-based powder are: C: 0.2%, Cr: 17%, Ni: 2.5%, B: 1%, Si: 0.6%, and the balance is Fe.

[0087] According to the weighed amount of FeB alloy powder, the introduced B element accounts for 1% of the total mass of the mixed powder. The element composition and mass percentage content of the FeB alloy powder are: C: 0.29%, B: 15.8%, Si: 0.25%, and the balance is Fe.

[0088] The sphericity of the iron-based metal powder is ≥90%, and the particle size distribution range is 48 - 75μm. The FeB alloy powder is irregular in shape, and the particle size distribution range is 38 - 48μm.

[0089] Put the weighed mixed powder into a planetary ball mill. The ball-to-material ratio is selected as 2:1, the ball milling time is 6h, and the ball milling speed is 120rpm.

[0090] Screen the ball-milled composite powder, and select the composite powder with a particle size range of 38 - 75μm.

[0091] The mass percentages of each element in the mixed powder are: C: 0.206%, Cr: 15.924%, Ni: 2.342%, B: 1.937%, Si: 0.578%, and the balance is Fe.

[0092] Use the above Fe2B-reinforced iron-based metal powder for ultra-high speed laser cladding to strengthen and repair the substrate surface. The specific steps are as follows:

[0093] Machine-process the substrate surface to remove the surface oxide film;

[0094] Wipe the substrate surface with anhydrous ethanol to remove the residual surface grease after machining;

[0095] Dry the powder, control the temperature at 100°C, and the time at 1h;

[0096] Ultra-high speed laser cladding was carried out with the following cladding process parameters: laser defocusing amount was +1 mm, laser power was 2300 W, laser scanning speed was 18 m / min, powder feeding speed was 24 g / min, and the overlap rate between tracks was 70%.

[0097] The thickness of the obtained coating was 245 μm.

[0098] The hardness of the coating was measured using a micro-Vickers hardness tester, and the average hardness reached 710 HV 0.2 . The self-corrosion voltage was measured as -0.502 V and the self-corrosion current was 8.728 μA using an electrochemical workstation.

[0099] The Vickers hardness of the substrate 45 steel was 320 HV 0.2 , the self-corrosion voltage was -0.612 V, and the self-corrosion current was 26.749 μA. The coating performance was significantly better than that of the substrate.

[0100] A reciprocating friction and wear experiment was carried out on the coating surface using a chromium steel ball, with a load of 30 N, a friction sliding distance of 10 mm, and a time of 40 min. The friction coefficient was as Figure 4 shown, and the volumetric wear loss was 6.386×10 -3 mm 3 . The volumetric wear loss of the substrate 45 steel was 5.552×10 -2 mm 3 . The volumetric wear loss of the coating was 11.5% of that of the substrate.

[0101] Metallographic microscopy observation found that there were no macroscopic cracks, pores and other defects in the coating. The surface quality of the product obtained in this example was good. After slight grinding, it could be comparable to the surface quality of electroplated products, but the hardness of the product still needed to be improved. Under the condition of slight grinding in Example 1, the surface roughness of the coating after grinding was R a = 0.9 μm. Before grinding, the roughness of the coating was R a = 10.5 μm.

[0102] Example 4

[0103] A certain amount of iron-based metal powder was weighed. The mass percentages of each element in the iron-based powder were: C: 0.2%, Cr: 17%, Ni: 2.5%, B: 1%, Si: 0.6%, and the balance was Fe.

[0104] According to a certain amount of FeB alloy powder weighed, the introduced B element accounted for 2% of the total mass of the mixed powder. The element composition and mass percentage content of the FeB alloy powder were: C: 0.29%, B: 15.8%, Si: 0.25%, and the balance was Fe.

[0105] The sphericity of the iron-based metal powder is ≥90%, and the particle size distribution range is 48 - 75 μm. The FeB alloy powder is irregular in shape, and the particle size distribution range is 38 - 48 μm.

[0106] Put the weighed mixed powder into a planetary ball mill, select a ball-to-material ratio of 2:1, a ball milling time of 6 h, and a ball milling speed of 120 rpm.

[0107] Screen the ball-milled composite powder, and select the composite powder with a particle size range of 38 - 75 μm.

[0108] The mass percentages of the elements in the mixed powder are C: 0.211%, Cr: 14.848%, Ni: 2.184%, B: 2.873%, Si: 0.556%, and the balance is Fe.

[0109] Use the above Fe2B-reinforced iron-based metal powder for ultra-high-speed laser cladding to strengthen and repair the surface of the substrate. The specific steps are as follows:

[0110] Machine the surface of the substrate to remove the surface oxide film;

[0111] Wipe the surface of the substrate with anhydrous ethanol to remove the residual surface grease after machining;

[0112] Dry the powder, control the temperature at 100 °C, and the time at 1 h;

[0113] Carry out ultra-high-speed laser cladding. The cladding process parameters are: laser defocus amount is +1 mm, laser power is 2300 W, laser scanning speed is 15 m / min, powder feeding speed is 24 g / min, and the overlap rate between tracks is 70%.

[0114] The thickness of the obtained coating is 250 μm. The surface roughness of the obtained coating is R a = 10.4 μm.

[0115] Use a micro-Vickers hardness tester to measure the hardness of the coating, and the average hardness can reach 880 HV 0.2 . Use an electrochemical workstation to measure the self-corrosion voltage as -0.548 V and the self-corrosion current as 7.941 μA.

[0116] The Vickers hardness of the substrate 45 steel is 320 HV 0.2 , the self-corrosion voltage is -0.612 V, and the self-corrosion current is 26.749 μA. The hardness value of the coating is significantly greater than that of the substrate, and the corrosion resistance is also very excellent.

[0117] Carry out a reciprocating friction and wear experiment on the surface of the coating with a chrome steel ball. The load is 30 N, the friction sliding distance is 10 mm, and the time is 40 min. Its friction coefficient is as Figure 4As shown, the volumetric wear amount is 5.715×10 -3 mm 3 . The volumetric wear amount of the substrate 45 steel is 5.552×10 -2 mm 3 . The volumetric wear amount of the coating is 10.29% of that of the substrate.

[0118] No holes and cracks were found in the coating, and the cross-sectional micro-morphology is as shown in Figure 2 and Figure 3 . The surface quality of the product obtained in this example is excellent. After slight grinding, it can be made equal to the surface quality of the electroplated product, and the hardness of the product also meets the relevant requirements. Under the conditions of slight grinding in Example 1, the surface roughness of the coating after grinding is R a = 0.7μm. Before grinding, the roughness of the coating is R a = 10.4μm.

[0119] Example 5

[0120] Weigh a certain amount of iron-based metal powder. The mass percentages of each element in the iron-based powder are: C: 0.2%, Cr: 17%, Ni: 2.5%, B: 1%, Si: 0.6%, and the balance is Fe.

[0121] According to the weighed amount of FeB alloy powder, the introduced B element accounts for 2% of the total mass of the mixed powder. The element composition and mass percentage content of the FeB alloy powder are: C: 0.29%, B: 15.8%, Si: 0.25%, and the balance is Fe.

[0122] The sphericity of the iron-based metal powder is ≥90%, and the particle size distribution range is 48 - 75μm. The FeB alloy powder is irregular in shape, and the particle size distribution range is 38 - 48μm.

[0123] Put the weighed mixed powder into a planetary ball mill. The ball-to-material ratio is selected as 2:1, the ball milling time is 6h, and the ball milling speed is 120rpm.

[0124] Screen the ball-milled composite powder, and select the composite powder with a particle size range of 38 - 75μm.

[0125] The mass percentages of each element in the mixed powder are: C: 0.211%, Cr: 14.848%, Ni: 2.184%, B: 2.873%, Si: 0.556%, and the balance is Fe.

[0126] Use the above Fe2B-reinforced iron-based metal powder for ultra-high-speed laser cladding to strengthen and repair the surface of the substrate. The specific steps are as follows:

[0127] Machine-process the surface of the substrate to remove the surface oxide film;

[0128] Wipe the surface of the substrate with absolute ethanol to remove the surface grease remaining after machining;

[0129] Dry the powder, control the temperature at 100 °C for 1 h;

[0130] Perform ultra-high-speed laser cladding. The cladding process parameters are: laser defocus amount is +1 mm, laser power is 2300 W, laser scanning speed is 15 m / min, powder feeding speed is 20 g / min, and the overlap rate between tracks is 70%.

[0131] The thickness of the obtained coating is 240 μm.

[0132] Use a micro-Vickers hardness tester to measure the hardness of the coating, and the average hardness can reach 870 HV 0.2 . The self-corrosion voltage measured by an electrochemical workstation is -0.55 V, and the self-corrosion current is 8.603 μA.

[0133] The Vickers hardness of the substrate 45 steel is 320 HV0.2, the self-corrosion voltage is -0.612 V, and the self-corrosion current is 26.749 μA. The hardness value of the coating is significantly greater than that of the substrate, and the corrosion resistance is also very excellent.

[0134] Metallographic microscopy observation shows that there are a small number of cracks in the cross-section of the coating. The surface quality of the product obtained in this example is good. After slight polishing, it can be comparable to the surface quality of electroplated products, and the hardness of the product also meets the relevant requirements. Under the condition of slight polishing in Example 1, the surface roughness of the polished coating is R a = 1.0 μm. Before polishing, the roughness of the coating is R a = 10.7 μm.

[0135] Example 6

[0136] Weigh a certain amount of iron-based metal powder. The mass percentages of each element in the iron-based powder are: C: 0.2%, Cr: 17%, Ni: 2.5%, B: 1%, Si: 0.6%, and the balance is Fe.

[0137] According to weighing a certain amount of FeB alloy powder, the introduced B element accounts for 2% of the total mass of the mixed powder. The element composition and mass percentage content of the FeB alloy powder are: C: 0.29%, B: 15.8%, Si: 0.25%, and the balance is Fe.

[0138] The sphericity of the iron-based metal powder ≥ 90%, and the particle size distribution range is 48 - 75 μm. The FeB alloy powder is irregular in shape, and the particle size distribution range is 38 - 48 μm.

[0139] Put the weighed mixed powder into a planetary ball mill, with the ball-to-powder ratio selected as 2:1, the ball milling time being 6 h, and the ball milling speed being 120 rpm.

[0140] Sieve the ball-milled composite powder to select the composite powder with a particle size range of 38 - 75 μm.

[0141] The mass percentages of the elements in the mixed powder are: C: 0.211%, Cr: 14.848%, Ni: 2.184%, B: 2.873%, Si: 0.556%, and the balance is Fe.

[0142] Use the above Fe₂B-reinforced iron-based metal powder for ultra-high-speed laser cladding to strengthen and repair the substrate surface. The specific steps are as follows:

[0143] Machine the substrate surface to remove the surface oxide film;

[0144] Wipe the substrate surface with anhydrous ethanol to remove the residual surface grease after machining;

[0145] Dry the powder, control the temperature at 100 °C for 1 h;

[0146] Carry out ultra-high-speed laser cladding. The cladding process parameters are: laser defocus amount is +1 mm, laser power is 2300 W, laser scanning speed is 15 m / min, powder feeding speed is 24 g / min, and the overlap rate between tracks is 80%.

[0147] The thickness of the obtained coating is 320 μm.

[0148] Macroscopic observation shows that the surface quality of the coating is poor and uneven. Under the condition of slight grinding in Example 1, the surface roughness of the ground coating is R a = 4.0 μm. Before grinding, the roughness of the coating is R a = 12 μm.

[0149] Example 7 (with the same process parameters as Example 4 but different powder compositions)

[0150] Weigh a certain amount of iron-based metal powder. The mass percentages of the elements in the iron-based powder are: C: 0.2%, Cr: 17%, Ni: 2.5%, B: 1%, Si: 0.6%, and the balance is Fe.

[0151] According to the weighed amount of FeB alloy powder, the introduced B element accounts for 3% of the total mass of the mixed powder. The element composition and mass percentage content of the FeB alloy powder are: C: 0.29%, B: 15.8%, Si: 0.25%, and the balance is Fe.

[0152] The sphericity of the iron-based metal powder is ≥90%, and the particle size distribution range is 48 - 75 μm. The FeB alloy powder is irregular in shape, and the particle size distribution range is 38 - 48 μm.

[0153] Put the weighed mixed powder into a planetary ball mill, select a ball-to-material ratio of 2:1, a ball milling time of 6 h, and a ball milling speed of 120 rpm.

[0154] Screen the ball-milled composite powder, and select the composite powder with a particle size range of 38 - 75 μm.

[0155] The mass percentages of the elements in the mixed powder are C: 0.217%, Cr: 13.772%, Ni: 2.025%, B: 3.81%, Si: 0.534%, and the balance is Fe.

[0156] Use the above Fe2B-reinforced iron-based metal powder for ultra-high-speed laser cladding to strengthen and repair the surface of the substrate. The specific steps are as follows:

[0157] Machine the surface of the substrate to remove the surface oxide film;

[0158] Wipe the surface of the substrate with anhydrous ethanol to remove the residual surface grease after machining;

[0159] Dry the powder, control the temperature at 100 °C for 1 h;

[0160] Perform ultra-high-speed laser cladding. The cladding process parameters are: laser defocus amount is +1 mm, laser power is 2300 W, laser scanning speed is 15 m / min, powder feeding speed is 24 g / min, and the overlap rate between tracks is 70%.

[0161] The thickness of the obtained coating is 300 μm.

[0162] Use a micro-Vickers hardness tester to measure the hardness of the coating, and the average hardness can reach 900 HV0.2. The self-corrosion voltage measured by an electrochemical workstation is -0.575 V, and the self-corrosion current is 8.529 μA.

[0163] The Vickers hardness of the substrate 45 steel is 320 HV0.2, the self-corrosion voltage is -0.612 V, and the self-corrosion current is 26.749 μA. The hardness value of the coating is significantly greater than that of the substrate, and the corrosion resistance is also better than that of the substrate.

[0164] A reciprocating friction and wear experiment was carried out on the surface of the coating with a chromium steel ball. The load was 30 N, the friction sliding distance was 10 mm, and the time was 40 min. Its friction coefficient is as Figure 4 shown, and the volumetric wear amount is 5.392×10 -3 mm 3The volume wear of the substrate 45 steel is 5.552×10 -2 mm 3 . The volume wear of the coating is 9.71% of that of the substrate volume wear.

[0165] Metallographic microscopy observation shows that there are a small number of cracks in the cross-section of the coating. The surface quality of the product obtained in this example is good. After slight polishing, it can be comparable to the surface quality of the electroplated product, and the hardness of the product also meets the relevant requirements. Under the condition of slight polishing in Example 1, the surface roughness of the coating after polishing is R a = 1.2μm. Before polishing, the roughness of the coating is R a = 11.2μm.

Claims

1. Application of Fe2B-reinforced iron-based metal powder for ultra-high speed laser cladding, characterized in that; It includes the following steps: On a clean and dry substrate surface, using the obtained ultra-high speed laser cladding Fe2B-reinforced iron-based metal powder as raw material; adopting an ultra-high speed laser cladding system to perform coating cladding; obtaining an Fe2B-reinforced iron-based metal coating; the process parameters during the cladding process are: laser defocus amount is +1 mm, laser power is 2000 - 2600 W, laser scanning speed is 12 - 18 m / min, powder feeding speed is 20 - 24 g / min, and the overlapping rate between tracks is 70% - 80%; The chemical composition and its mass percentage of the powder used for ultra-high speed laser cladding are: C: 0.1 - 0.4%, Cr: 12 - 16%, Ni: 1 - 3%, B: 2.5 - 3.9%, Si: 0 - 1%, and the balance is Fe; The powder raw material used for the ultra-high speed laser cladding includes Fe-B alloy powder and iron-based metal powder; The mass percentage of the B element introduced in the Fe-B alloy powder in the Fe2B-reinforced iron-based metal powder is 1 - 4%; The content of each element and its mass percentage in the iron-based metal powder are: C: 0.1 - 0.4%, Cr: 15 - 18%, Ni: 1 - 3%, B: 0 - 1%, Si: 0 - 1%, and the balance is Fe; The Fe2B-reinforced iron-based metal powder for ultra-high speed laser cladding is prepared through the following steps: Step 1: Weigh the iron-based metal powder and Fe-B alloy powder in proportion, where the B element introduced by the Fe-B alloy powder accounts for 1 - 4% of the total mass of the mixed powder; Step 2: Place the configured powders together in a ball mill for ball milling treatment. The ball milling time of the mixed powder is 6 - 8 h, and the ball milling speed is 120 - 160 rpm; Step 3: Perform particle size screening on the ball-milled composite powder, and screen out the powder with a particle size of 38 - 75 μm to obtain the Fe2B-reinforced iron-based metal powder for ultra-high speed laser cladding.

2. Application of Fe2B reinforced iron-based metal powder for ultra-high speed laser cladding according to claim 1, characterized in that: The Fe-B alloy powder includes the following components by mass percentage: C: 0.25 - 0.3%, B: 15 - 16%, Si: 0.2 - 0.3%, and the balance is Fe.

3. According to the application of an Fe2B-reinforced iron-based metal powder for ultra-high speed laser cladding as described in claim 1, it is characterized in that: The Fe-B alloy powder is irregular in shape, and the particle size distribution range is 38 - 48 μm; The sphericity of the iron-based metal powder is ≥90%, and the particle size distribution range is 48 - 75 μm.

4. Application of Fe2B-reinforced iron-based metal powder for ultra-high speed laser cladding according to claim 1, characterized in that; The process parameters during the cladding process are: laser defocus amount is +1 mm, laser power is 2300 - 2600 W, laser scanning speed is 15 - 18 m / min, powder feeding speed is 20 - 24 g / min, and the overlapping rate between tracks is 70% - 75%.

5. The application of the Fe2B-reinforced iron-based metal powder for ultra-high speed laser cladding according to claim 4, characterized in that; The process parameters during the cladding process are: laser power is 2300 - 2400 W, laser scanning speed is 15 - 16 m / min, powder feeding speed is 23 - 24 g / min, and the overlapping rate between tracks is 70% - 72%.

6. Application of Fe2B reinforced iron-based metal powder for ultra-high speed laser cladding according to claim 1, characterized in that: In step 1, the B element introduced by the Fe-B alloy powder accounts for 1 - 3% of the total mass of the mixed powder.

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