A method for improving the hardness and wear resistance of low alloy steels

Abstract

This invention discloses a method for improving the hardness and wear resistance of low-alloy steel, comprising: powder specification selection: the low-alloy steel powder has a particle size of 75~180μm, and the short-cut carbon fiber powder has a diameter of 5~10μm and a length of 40~50μm; powder mixing: mixing short-cut carbon fiber powder into the low-alloy steel powder, wherein the weight percentage of short-cut carbon fiber powder in the mixed powder is 0.8~1.0wt.%; pre-powdering: spreading the mixed powder on a target substrate and scraping and compacting it to form a mixed powder layer; laser cladding: performing laser cladding on the mixed powder layer on the target substrate, with a laser power of 1900~2100W and a laser scanning speed of 7~9mm / s. This invention is simple, efficient, and economical, requiring no additional equipment investment or process steps, while significantly improving the hardness of low-alloy steel and correspondingly significantly enhancing its wear resistance, with a hardness increase of up to 130% or more.

Description

Technical Field

[0001] This invention belongs to the field of laser cladding low alloy steel technology, specifically relating to a method for improving the hardness and wear resistance of low alloy steel. Background Technology

[0002] Low-alloy steel, achieved by adding small amounts of alloying elements to carbon steel, significantly improves its performance and is one of the key materials widely used in modern industry. To improve the hardness and wear resistance of low-alloy steel to meet practical application requirements, a low-alloy steel coating can be laser-clad onto the target substrate using laser cladding technology.

[0003] Based on laser cladding of low-alloy steel coatings, the following methods are currently available to improve the hardness and wear resistance of low-alloy steel: Method 1: Process optimization. Performance is improved by optimizing laser energy density through adjusting laser cladding process parameters such as laser power and scanning speed.

[0004] Method 2: Introducing a physical field. By adding preheating, ultrasonic vibration, and other steps during the laser cladding process, the temperature and stress fields of the molten pool can be improved, thereby enhancing performance.

[0005] The existing methods described above have the following drawbacks: 1. The process optimization iterations take a long time and the performance improvement is limited (hardness improvement is about 5%). Furthermore, after optimization, there are problems such as laser energy attenuation as the machine runs for longer periods of time, and parameters need to be calibrated regularly.

[0006] 2. Introducing preheating, ultrasonic vibration and other steps adds extra processes, which reduces overall efficiency and provides only limited performance improvement (hardness improvement of about 15%). Summary of the Invention

[0007] To address some or all of the technical problems existing in the prior art, the present invention provides a method for improving the hardness and wear resistance of low-alloy steel based on laser cladding of low-alloy steel coatings, comprising the following steps: (1) Selection of powder specifications: The particle size of low alloy steel powder is selected as 75~180μm, and the diameter of short carbon fiber powder is selected as 5~10μm and the length is selected as 40~50μm; (2) Powder mixing: Short-cut carbon fiber powder is uniformly mixed into low-alloy steel powder to form a mixed powder, wherein the weight percentage of short-cut carbon fiber powder in the mixed powder is 0.8~1.0 wt.%; (3) Pre-powder: Spread the mixed powder on the target substrate, and use a pressure plate to scrape and compact it to form a mixed powder layer; (4) Laser cladding: Laser cladding is performed on the mixed powder layer on the target substrate to form a laser cladding low alloy steel coating. The laser cladding process parameters are set as follows: laser power 1900~2100W, laser scanning speed 7~9mm / s.

[0008] Furthermore, in the above method for improving the hardness and wear resistance of low alloy steel, steps (3) and (4) are repeated according to the actual required thickness of the laser cladding low alloy steel coating. After pre-setting a mixed powder layer, a mixed powder layer is laser cladding. By cladding layer by layer, the coating reaches the target thickness.

[0009] Furthermore, in the above-mentioned method for improving the hardness and wear resistance of low alloy steel, the overlap rate of laser cladding is set to 30-40%.

[0010] Furthermore, in the above-mentioned method for improving the hardness and wear resistance of low alloy steel, the thickness of each layer of mixed powder is controlled to be 0.5±0.05mm.

[0011] The method of the present invention for improving the hardness and wear resistance of low alloy steel is simple, efficient, and economical. It does not require additional equipment investment or process steps, and can significantly improve the hardness of low alloy steel and correspondingly significantly improve its wear resistance. The hardness improvement is up to 130% or more, and it has broad application prospects in the field of laser cladding of low alloy steel. Attached Figure Description

[0012] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0013] Figure 1 A comparison chart showing the improvement in hardness properties between low-alloy steel without the treatment of this invention and low-alloy steel treated with this invention; Figure 2 The image shows the morphology of wear pits in a friction and wear test of low alloy steel that has not been treated according to the present invention. Figure 3 The image shows the morphology of wear pits in a friction and wear test of low alloy steel treated with the present invention. Detailed Implementation

[0014] To make the objectives, technical solutions, and advantages of this invention clearer, the technical solutions of this invention will be clearly and completely described below in conjunction with specific embodiments. Obviously, the described embodiments are only a part of the embodiments of this invention, and not all of them. All other embodiments obtained by those skilled in the art based on the embodiments of this invention without creative effort are within the scope of protection of this invention.

[0015] This invention, based on laser cladding of low-alloy steel coatings, provides a method for improving the hardness and wear resistance of low-alloy steel by optimizing processes and introducing physical fields, which differs from existing technologies. This method can more easily and efficiently improve the hardness and wear resistance of low-alloy steel, with a hardness increase of up to about 130%.

[0016] Specifically, the method of the present invention for improving the hardness and wear resistance of low alloy steel follows the process route of powder specification selection → powder mixing → pre-powder placement → laser cladding process parameter setting → laser cladding, and includes the following steps: (1) Selection of powder specifications: The particle size of low alloy steel powder is selected as 75~180μm, and the diameter of short carbon fiber powder is selected as 5~10μm and the length is selected as 40~50μm; (2) Powder mixing: Short-cut carbon fiber powder is uniformly mixed into low-alloy steel powder to form a mixed powder, wherein the weight percentage of short-cut carbon fiber powder in the mixed powder is 0.8~1.0 wt.%; (3) Pre-powder: Spread the mixed powder on the target substrate, and use a pressure plate to scrape and compact it to form a mixed powder layer; (4) Laser cladding: Laser cladding is performed on the mixed powder layer on the target substrate to form a laser cladding low alloy steel coating. The laser cladding process parameters are set as follows: laser power 1900~2100W, laser scanning speed 7~9mm / s.

[0017] According to the actual required thickness of the laser cladding low alloy steel coating, when implementing the method of the present invention for improving the hardness and wear resistance of low alloy steel, steps (3) and (4) can be repeated, a mixed powder layer is pre-placed and then a mixed powder layer is laser claddinged, thereby cladding layer by layer until the coating reaches the target thickness.

[0018] Preferably, in the method of the present invention for improving the hardness and wear resistance of low alloy steel, the thickness of each layer of mixed powder is controlled to be 0.5 ± 0.05 mm.

[0019] Preferably, in the method of the present invention for improving the hardness and wear resistance of low alloy steel, the overlap rate of laser cladding is set to 30-40%.

[0020] The following specific embodiments further illustrate the method of the present invention for improving the hardness and wear resistance of low alloy steel.

[0021] Example 1 Example 1 describes the laser cladding of a 5mm thick low-alloy steel coating onto a target substrate, comprising the following steps: (1) Select low alloy steel powder with a particle size of 90~150μm and short carbon fiber powder with a diameter of 6~8μm and a length of 40~45μm; (2) Short carbon fiber powder is uniformly mixed into low alloy steel powder to form a mixed powder, wherein the weight percentage of short carbon fiber powder in the mixed powder is 0.9 wt.%; (3) Spread the mixed powder on the target substrate, and use a pressure plate to scrape and compact it to form a first mixed powder layer with a thickness of 0.5 mm; (4) Laser cladding is performed on the first mixed powder layer on the target substrate. The laser power is 2000W, the laser scanning speed is 8mm / s, and the overlap rate is 35%. (5) After completing the laser cladding of the first mixed powder layer, repeat steps (3) and (4) above. By pre-setting the second mixed powder layer, the third mixed powder layer and the tenth mixed powder layer with a thickness of 0.5 mm on the target substrate and performing laser cladding layer by layer, a target coating with a thickness of 5 mm is finally obtained.

[0022] The hardness of low-alloy steel without the treatment of this invention (hereinafter referred to as "conventional sample") and low-alloy steel treated with this invention (hereinafter referred to as "invention sample") were compared and tested. Figure 1 As shown, microhardness tests were performed on the outer plane of both conventional and the present invention's samples, and at distances of 0.3 mm, 0.6 mm, 0.9 mm, 1.2 mm, 1.5 mm, 1.8 mm, 2.1 mm, 2.4 mm, and 2.7 mm from the outer surface. The average microhardness of the longitudinal section of the conventional sample was 358 HV, while the average microhardness of the longitudinal section of the present invention's sample was 836 HV, representing a hardness increase of over 130%. Therefore, by implementing the method of the present invention for improving the hardness and wear resistance of low-alloy steel, the hardness of low-alloy steel can be significantly improved, thereby significantly improving its wear resistance.

[0023] In addition, the wear pit morphology after friction and wear tests on conventional samples and the samples of the present invention was compared, such as... Figure 2 As shown, low-alloy steel not treated with this invention exhibits large, obvious wear pits after friction and wear tests, with extremely high wear. However, as... Figure 3As shown, the low-alloy steel treated with the present invention showed no obvious wear pits after friction and wear tests under the same conditions, with only a small number of wear marks and extremely low wear. This further confirms that the method of the present invention for improving the hardness and wear resistance of low-alloy steel can significantly improve the wear resistance of low-alloy steel.

[0024] In summary, the method of the present invention for improving the hardness and wear resistance of low alloy steel has the following advantages and beneficial effects: (1) This invention is simple, efficient and economical, and does not require additional equipment investment or process steps.

[0025] (2) The present invention can significantly improve the hardness of low alloy steel and correspondingly significantly improve the wear resistance of low alloy steel, with the hardness increase reaching more than 130%.

[0026] In the description of this specification, references to terms such as "embodiment," "example," etc., indicate that a specific feature, structure, material, or characteristic described in connection with that embodiment or example is included in at least one embodiment or example of the present invention. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, those skilled in the art can combine or combine the different embodiments or examples described in this specification and the features therein without causing contradiction.

[0027] It should be noted that, unless otherwise specified, the terms used herein have the meanings commonly understood by those skilled in the art. Furthermore, when a numerical range is disclosed herein, the range is considered continuous and includes the minimum and maximum values ​​of the range, as well as every value between such minimum and maximum. Further, when the range refers to integers, it includes every integer between the minimum and maximum values ​​of the range. Moreover, when multiple ranges are provided to describe features, the ranges may be combined. In other words, unless otherwise specified, all ranges disclosed herein should be understood to include any and all subranges to which they are incorporated.

[0028] It should also be noted that, in this document, the term "comprising" or any other variation thereof is intended to cover non-exclusive inclusion, such that an article or device that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such an article or device.

[0029] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, and are not intended to limit them. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features. Such modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the present invention.

Claims

1. A method for improving the hardness and wear resistance of low-alloy steel, characterized in that, Includes the following steps: (1) Selection of powder specifications: The particle size of low alloy steel powder is selected as 75~180μm, and the diameter of short carbon fiber powder is selected as 5~10μm and the length is selected as 40~50μm; (2) Powder mixing: Short-cut carbon fiber powder is uniformly mixed into low-alloy steel powder to form a mixed powder, wherein the weight percentage of short-cut carbon fiber powder in the mixed powder is 0.8~1.0 wt.%; (3) Pre-powder: Spread the mixed powder on the target substrate, and use a pressure plate to scrape and compact it to form a mixed powder layer; (4) Laser cladding: Laser cladding is performed on the mixed powder layer on the target substrate to form a laser cladding low alloy steel coating. The laser cladding process parameters are set as follows: laser power 1900~2100W, laser scanning speed 7~9mm / s.

2. The method for improving the hardness and wear resistance of low-alloy steel as described in claim 1, characterized in that, According to the actual required thickness of the laser cladding low alloy steel coating, repeat steps (3) and (4), pre-place a layer of mixed powder and then laser clad a layer of mixed powder. By cladding layer by layer, the coating reaches the target thickness.

3. The method for improving the hardness and wear resistance of low-alloy steel as described in claim 1, characterized in that, The overlap rate of laser cladding is set to 30-40%.

4. The method for improving the hardness and wear resistance of low-alloy steel as described in any one of claims 1 to 3, characterized in that, The thickness of each layer of mixed powder is controlled to be 0.5±0.05mm.

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