An iron-based amorphous alloy powder for laser cladding

Abstract

The present invention relates to an iron-based amorphous alloy powder for laser cladding, comprising components in the following mass percentages: 0.6 - 1.2% of carbon (C); 0.5 - 1.0% of silicon (Si); 0.5 - 1.0% of boron (B); 20 - 25% of chromium (Cr); 18 - 23% of molybdenum (Mo); the balance being iron (Fe), and the sum of their weights being 100%. By defining the components and their contents, the iron-based amorphous alloy powder proposed by the present invention is suitable for workpieces that require a laser cladding surface alloy layer with high hardness, high wear resistance, and high corrosion resistance for long-term operation in the temperature range of -45°C to 500°C, such as workpieces like molds, screws, and guide rails. The obtained laser cladding iron-based amorphous alloy powder has good process performance, and a large-area laser cladding iron-based amorphous alloy with a certain thickness and no cracks can be obtained without preheating and subsequent heat treatment. The cladding layer has high strength, hardness, and wear resistance, and good corrosion resistance.

Description

Technical Field

[0001] The present invention relates to the technical field of alloy materials, and particularly relates to an iron-based amorphous alloy powder for laser cladding. Background Art

[0002] Amorphous alloys, also known as metallic glasses, are metallic materials with a long-range disordered and short-range ordered atomic arrangement. They possess the characteristics of both ordinary metals and glasses and do not have common defects such as grain boundaries and dislocations in crystalline materials. Iron-based amorphous alloys have advantages such as high hardness, high strength, high wear resistance, high corrosion resistance, and low cost, and have broad application prospects in the field of surface coatings. Currently, the main methods for preparing iron-based amorphous alloys on the surface of parts are spraying (such as supersonic spraying and plasma spraying) and corresponding iron-based amorphous alloy powders. However, the biggest problem with the coatings obtained by spraying is the low bonding strength between the coating and the part substrate, which is about 60 MPa. If the part is subjected to large forces during operation, the coating is likely to peel off, resulting in part failure, which greatly limits the use of iron-based amorphous alloys.

[0003] Compared with traditional surface coating technologies, such as conventional surfacing, supersonic spraying, and electroplating, laser cladding technology, as a new surface treatment technology, has the advantages of fine grains in the cladding layer, strong bonding between the cladding layer and the substrate (bonding strength ≥ 600 MPa), and small heat affected zone and thermal deformation. Therefore, some researchers hope to use laser cladding technology and iron-based amorphous alloy powder to prepare iron-based amorphous alloy coatings. However, the biggest problem with current iron-based amorphous alloy powder used for laser cladding is that the coating is prone to cracking. Once cracks occur in the coating, the corrosion resistance of the coating is very poor, and the cracks are prone to expand during the working process of the part, resulting in part cracking and failure. The main measures to solve the easy cracking of laser cladding iron-based amorphous alloy coatings currently are: (1) adding a large proportion of soft phases. Although this method can eliminate coating cracks, it significantly reduces the hardness and wear resistance of the coating; (2) preheating and post-heating. Although this method can also eliminate coating cracks, it significantly reduces the cooling rate of the coating, thus significantly reducing the amorphous degree of the coating and reducing the advantages of amorphous alloys. In addition, adding preheating and post-heating processes in actual production also increases the production difficulty. Due to the above problems, iron-based amorphous alloy powder is rarely used in laser cladding technology, seriously hindering the application of iron-based amorphous alloys and their powders. Currently, most of the iron-based amorphous alloy powders used in laser cladding still follow the iron-based amorphous powders used for spraying. In order to pursue high hardness and high wear resistance of the coating, most of these powders have a high C content (C > 1.5% wt) or a high B content (B > 1.5% wt) or a high Si content (Si > 1.5% wt). Since the internal bonding of the spraying coating is mechanical and there will be no cracking problem with the coating, there will be no problem with a high C content or a high B content or a high Si content in the composition design of the corresponding iron-based amorphous alloy powder. However, the internal physical metallurgical processes of laser cladding and spraying are different. High contents of boron and silicon in the alloy powder make it impossible for some inclusions such as borosilicates to float out of the rapidly solidified molten pool smoothly during the laser cladding process, resulting in high cracking sensitivity of the laser cladding layer. The cracking phenomenon is particularly obvious when the hardness of the laser cladding layer is high. In addition, a high carbon content in the alloy will also increase the brittleness and cracking sensitivity of the laser cladding coating. In short, the iron-based amorphous alloy powder currently used for laser cladding has great limitations and is difficult to apply. Summary of the Invention

[0004] The object of the present invention is to provide an iron-based amorphous alloy powder for laser cladding to avoid the deficiencies in the above-mentioned prior art.

[0005] This iron-based amorphous alloy powder can obtain a laser cladding amorphous iron-based alloy with high hardness, high wear resistance, and no cracks without preheating and post-heating slow cooling. This iron-based alloy also has high corrosion resistance and a relatively low price.

[0006] To achieve the above object, the technical solution adopted by the present invention is as follows: An iron-based amorphous alloy powder for laser cladding, comprising raw materials in the following mass percentages: 0.6 - 1.2% of carbon (C); 0.5 - 1.0% of silicon (Si); 0.5 - 1.0% of boron (B); 20 - 25% of chromium (Cr); 18 - 23% of molybdenum (Mo); the balance is iron (Fe), and the sum of their weights is 100%.

[0007] Preferably, it comprises raw materials in the following mass percentages: 0.9% of carbon (C); 0.75% of silicon (Si); 0.75% of boron (B); 22.5% of chromium (Cr); 20.5% of molybdenum (Mo); the balance is iron (Fe), and the sum of their weights is 100%.

[0008] Preferably, it comprises the following steps: Weigh pure iron, iron-carbon alloy, ferroboron, silicon block, metal chromium block and molybdenum rod according to the ratio, put all the raw materials into induction heating and melting, and after the melting is completed, obtain an iron-based amorphous alloy powder with a particle size of 20 - 180 μm by gas atomization or water atomization and then screening.

[0009] The present invention has the following advantages compared with the prior art:

[0010] By limiting the composition and its content, the present application proposes that the iron-based amorphous alloy powder is suitable for workpieces that need to work in the temperature range of -45°C to 500°C for a long time and require a laser cladding surface alloy layer with high hardness, high wear resistance and high corrosion resistance, such as workpieces like molds, screws and guide rails. The obtained laser cladding iron-based amorphous alloy powder has good process performance, and a large-area laser cladding iron-based amorphous alloy with a certain thickness and no cracks can be obtained without preheating and subsequent heat treatment. The cladding layer has high strength, hardness and wear resistance, and good corrosion resistance. Detailed Embodiments

[0011] In order to enable those skilled in the art to better understand the technical solution of the present invention, the present invention will be described in detail below. The description of this part is only exemplary and explanatory, and should not have any restrictive effect on the protection scope of the present invention.

[0012] Example 1

[0013] An iron-based amorphous alloy powder for laser cladding, comprising components in the following mass percentages: 0.6% of carbon (C); 0.5% of silicon (Si); 0.5% of boron (B); 20% of chromium (Cr); 18% of molybdenum (Mo); the balance is iron (Fe), and the sum of their weights is 100%.

[0014] The preparation method of the above-mentioned iron-based amorphous alloy powder comprises the following steps: Weigh pure iron, iron-carbon alloy, ferroboron, silicon block, metal chromium block and molybdenum rod according to the ratio, put all the raw materials into induction heating and melting, and after the melting is completed, obtain iron-based amorphous alloy powder with a particle size of 23-180 μm for the alloy powder through gas atomization or water atomization and then screening.

[0015] The prepared iron-based amorphous alloy powder is used for laser cladding. A 3-kilowatt semiconductor laser is used for laser cladding, with a spot diameter of 5 mm and a laser scanning speed of 6 mm / s. By adjusting the powder feeding rate and subsequent machining, metal specimens with laser cladding layer thicknesses of 0.8 mm and 0.25 mm are obtained respectively. The above specimens are inspected by a coloring flaw detector, and there are no cracks in the laser cladding layers. The specimen with a laser cladding layer thickness of 0.8 mm is measured by a Rockwell hardness tester, and the hardness of the cladding layer is 65 HRC. The metal specimen with a cladding layer thickness of 0.25 mm is subjected to a copper-accelerated acetic acid salt spray test (CASS test) according to the national standard (GB / T 10125), and the time when no rust spots appear on the surface is observed. The result is that there are no obvious rust spots on the surface of the laser cladding layer within 2200 hours, and obvious rust spots begin to appear on the surface of the laser cladding layer after more than 2200 hours.

[0016] Example 2

[0017] An iron-based amorphous alloy powder for laser cladding, comprising the following components in mass percentages: 0.9% of carbon (C); 0.75% of silicon (Si); 0.75% of boron (B); 22.5% of chromium (Cr); 20.5% of molybdenum (Mo); the balance is iron (Fe), and the sum of their weights is 100%.

[0018] The preparation method of the above-mentioned iron-based amorphous alloy powder comprises the following steps: Weigh pure iron, iron-carbon alloy, ferroboron, silicon block, metal chromium block and molybdenum rod according to the ratio, put all the raw materials into induction heating and melting, and after the melting is completed, obtain iron-based amorphous alloy powder with a particle size of 23-180 μm for the alloy powder through gas atomization or water atomization and then screening.

[0019] The prepared iron-based amorphous alloy powder is used for laser cladding. A 3-kilowatt semiconductor laser is used for laser cladding with a spot diameter of 5 mm and a laser scanning speed of 6 mm / s. By adjusting the powder feeding rate and subsequent machining, metal specimens with laser cladding layer thicknesses of 0.8 mm and 0.25 mm are obtained respectively. The above specimens are inspected using a dye penetrant inspection agent, and no cracks are found in the laser cladding layers. The hardness of the cladding layer of the specimen with a laser cladding layer thickness of 0.8 mm is measured using a Rockwell hardness tester to be 67 HRC. The metal specimen with a cladding layer thickness of 0.25 mm is subjected to a copper-accelerated acetic acid salt spray test (CASS test) according to the national standard (GB / T 10125), and the time when no rust spots appear on the surface is observed. The result is that within 2100 hours, no obvious rust spots appear on the surface of the laser cladding layer, and after more than 2100 hours, obvious rust spots begin to appear on the surface of the laser cladding layer.

[0020] Example 3

[0021] An iron-based amorphous alloy powder for laser cladding, comprising the following components in mass percentages: 1.2% carbon (C); 1.0% silicon (Si); 1.0% boron (B); 25% chromium (Cr); 23% molybdenum (Mo); the balance is iron (Fe), and the sum of their weights is 100%.

[0022] The preparation method of the above iron-based amorphous alloy powder includes the following steps: Weigh pure iron, iron-carbon alloy, ferroboron, silicon blocks, metal chromium blocks, and molybdenum rods according to the ratio, put all the raw materials into induction heating and melting, and after completion of melting, obtain iron-based amorphous alloy powder with a particle size of 23 - 180 μm by gas atomization or water atomization and then screening.

[0023] The prepared iron-based amorphous alloy powder is used for laser cladding. A 3-kilowatt semiconductor laser is used for laser cladding with a spot diameter of 5 mm and a laser scanning speed of 6 mm / s. By adjusting the powder feeding rate and subsequent machining, metal specimens with laser cladding layer thicknesses of 0.8 mm and 0.25 mm are obtained respectively. The above specimens are inspected using a dye penetrant inspection agent, and no cracks are found in the laser cladding layers. The hardness of the cladding layer of the specimen with a laser cladding layer thickness of 0.8 mm is measured using a Rockwell hardness tester to be 69 HRC. The metal specimen with a cladding layer thickness of 0.25 mm is subjected to a copper-accelerated acetic acid salt spray test (CASS test) according to the national standard (GB / T 10125), and the time when no rust spots appear on the surface is observed. The result is that within 1900 hours, no obvious rust spots appear on the surface of the laser cladding layer, and after more than 1900 hours, obvious rust spots begin to appear on the surface of the laser cladding layer.

[0024] Control Group 1: 316L (Note: A product already on the market)

[0025] Product formula, mass percentage of components: 0.03% carbon (C), 1.0% silicon (Si), 12% nickel (Ni), 18% chromium (Cr), 2.2% molybdenum (Mo), 1.5% manganese (Mn), the balance being iron (Fe), and the sum of their weights being 100%.

[0026] Control group 2: Fe55 (Note: A product already on the market)

[0027] Product formula, mass percentage of components: 0.15% carbon (C), 0.9% boron (B), 1.2% silicon (Si), 2.8% nickel (Ni), 17% chromium (Cr), 0.5% molybdenum (Mo), 0.2% manganese (Mn), 0.19% vanadium (V), the balance being iron (Fe), and the sum of their weights being 100%.

[0028] Using the powders of control groups 1 and 2, laser cladding was carried out with a 3-kilowatt semiconductor laser, the spot diameter was 5 mm, and the laser scanning speed was 6 mm / s. By adjusting the powder feeding rate and subsequent machining, metal specimens with laser cladding layer thicknesses of 0.8 mm and 0.25 mm were obtained for control groups 1 and 2 respectively. Penetrant inspection was carried out, and no cracks were found in the laser cladding layers. The Rockwell hardness tester was used to measure the hardness of the cladding layer of the control group 1 powder specimen with a laser cladding layer thickness of 0.8 mm, which was 34 HRC. The Rockwell hardness tester was used to measure the hardness of the cladding layer of the control group 2 powder specimen with a laser cladding layer thickness of 0.8 mm, which was 56 HRC. The metal specimens with a laser cladding layer thickness of 0.25 mm of the control group 1 powder and the metal specimens with a laser cladding layer thickness of 0.25 mm of the control group 2 powder were also subjected to the copper-accelerated acetic acid salt spray test (CASS test) according to the national standard (GB / T 10125). The time when no surface rust spots appeared was observed, and the results were as follows: within 1250 hours, no obvious rust spots appeared on the surface of the laser cladding layer of the control group 1 powder; after more than 1250 hours, obvious rust spots began to appear on the surface of the laser cladding layer. Within 70 hours, no obvious rust spots appeared on the surface of the laser cladding layer of the control group 2 powder; after more than 70 hours, obvious rust spots began to appear on the surface of the laser cladding layer.

[0029] From the test results of the above comparison groups, it can be concluded that although the laser cladding layer of the powder metal specimen in Comparison Group 1 has good corrosion resistance, its hardness is too low. While the hardness of the laser cladding layer of the powder metal specimen in Comparison Group 2 is relatively high, it is still lower than that of the laser cladding layer of the iron-based amorphous alloy powder metal specimen of the present application. More importantly, the corrosion resistance of the laser cladding layer of the powder metal specimen in Comparison Group 2 is significantly worse than that of the laser cladding layer of the iron-based amorphous alloy powder metal specimen of the present application. Due to reasons such as too low hardness or poor corrosion resistance, the use of the laser cladding layers of the powders in Comparison Group 1 and Comparison Group 2 is subject to certain limitations. However, the laser cladding layer of the iron-based amorphous alloy powder of the present application has good performance in both corrosion resistance and hardness, and can be used for laser cladding of parts such as molds, screws, and guide rails, having high economic value and being necessary for wide promotion.

[0030] It should be noted that in this article, the term "including", "comprising" or any other variant thereof is intended to cover non-exclusive inclusion, so that a process, method, article or device including a series of elements not only includes those elements, but also includes other elements not expressly listed, or further includes elements inherent to such process, method, article or device.

[0031] In this article, specific examples are used to elaborate on the principles and implementation manners of the present invention. The description of the above examples is only used to help understand the method and its core idea of the present invention. The above are only the preferred implementation manners of the present invention. It should be pointed out that due to the limited nature of written expression and objectively infinite specific structures, for those of ordinary skill in the art of this technology, without departing from the principles of the present invention, several improvements, refinements or changes can be made, or the above technical features can be combined in an appropriate manner; these improvements, refinements, changes or combinations, or directly applying the concept and technical solution of the invention to other occasions without improvement, shall all be regarded as the protection scope of the present invention.

Claims

1. An iron-based amorphous alloy powder for laser cladding, characterized in that, Comprising components in the following mass percentages: 0.6 - 1.2% of carbon (C); 0.5 - 1.0% of silicon (Si); 0.5 - 1.0% of boron (B); 20 - 25% of chromium (Cr); 18 - 23% of molybdenum (Mo); the balance being iron (Fe), and the sum of their weights being 100%.

2. The iron-based amorphous alloy powder for laser cladding according to claim 1, wherein Comprising components in the following mass percentages: 0.9% of carbon (C); 0.75% of silicon (Si); 0.75% of boron (B); 22.5% of chromium (Cr); 20.5% of molybdenum (Mo); the balance being iron (Fe), and the sum of their weights being 100%.

3. The preparation method of an iron-based amorphous alloy powder for laser cladding according to claim 1 or 2, characterized in that, Including the following steps: Weigh pure iron, ferrocarbon alloy, ferroboron, silicon block, metal chromium block and molybdenum rod according to the ratio, put all the raw materials into induction heating and melting, and after completion of melting, obtain iron-based amorphous alloy powder with a particle size of 23 - 180 μm by gas atomization or water atomization followed by screening.