阅读说明：本技术 用于金属工件的局部渗碳方法及金属工件 (Method for local carburization of a metal workpiece and metal workpiece ) 是由 王越 郭学佳 黄声野 于 2020-11-12 设计创作，主要内容包括：本发明提供一种用于金属工件的局部渗碳方法及金属工件,所述方法包括以下步骤：清理金属工件的待渗碳表面；将碳粉及酒精按比例混合成渗碳剂,将渗碳剂均匀的涂覆在所述待渗碳表面；将涂覆有渗碳剂的所述金属工件放入真空炉中烘干；将烘干的所述金属工件放置在惰性气体保护环境中,采用激光束对所述金属工件的待渗碳区域进行激光融化或激光烧结。该局部渗碳方法基于采用局部激光融化或局部激光烧结工艺完成金属工件的渗碳处理,方法简单、操作方便；可有效降低经济成本及时间成本；有效的提高了金属的耐磨性及疲劳强度。(The invention provides a local carburizing method for a metal workpiece and the metal workpiece, wherein the method comprises the following steps: cleaning the surface to be carburized of the metal workpiece; mixing carbon powder and alcohol in proportion to form a carburizing agent, and uniformly coating the carburizing agent on the surface to be carburized; putting the metal workpiece coated with the carburizing agent into a vacuum furnace for drying; and placing the dried metal workpiece in an inert gas protection environment, and carrying out laser melting or laser sintering on the area to be carburized of the metal workpiece by adopting a laser beam. The local carburization method is based on the carburization treatment of the metal workpiece completed by adopting a local laser melting or local laser sintering process, and has the advantages of simple method and convenient operation; the economic cost and the time cost can be effectively reduced; effectively improves the wear resistance and fatigue strength of the metal.)

1. A method of partially carburizing a metal workpiece, characterized by comprising the steps of:

cleaning the surface to be carburized of the metal workpiece;

mixing carbon powder and alcohol in proportion to form a carburizing agent, and uniformly coating the carburizing agent on the surface to be carburized;

putting the metal workpiece coated with the carburizing agent into a vacuum furnace for drying;

and placing the dried metal workpiece in an inert gas protection environment, and carrying out laser melting or laser sintering on the area to be carburized of the metal workpiece by adopting a laser beam.

2. The method of partially carburizing a metal workpiece according to claim 1, characterized in that the mass fraction ratio of the carbon powder and the alcohol is 2: 8.

3. The partial carburization method for a metal workpiece according to claim 1, characterized in that the carbon powder has a particle size in a range of 10mm to 20 mm.

4. The partial carburizing method for metal workpiece according to claim 1, characterized in that, in the step of putting the metal workpiece coated with the carburizing agent into a vacuum furnace for drying, the drying temperature is 70 ℃, and the drying time is 60 minutes.

5. The partial carburizing method for the metal workpiece according to claim 4, characterized in that a degree of vacuum in the vacuum furnace is 0.5Pa or less.

6. The partial carburization method for a metal workpiece according to claim 1, characterized in that the oxygen content of the inert gas is not higher than 1000 ppm.

7. The method of partial carburization of a metal workpiece according to claim 1, characterized in that the material of the metal workpiece is low carbon steel or low carbon alloy steel.

8. The partial carburizing method for metal workpieces according to claim 1, characterized in that a carburizing agent is uniformly coated on the surface to be carburized by a method comprising: and immersing the whole metal workpiece into the carburizing agent, taking out and draining.

9. The partial carburizing method for the metal workpiece according to any one of claims 1 to 8, characterized in that, in the step of laser melting or laser sintering the region of the metal workpiece to be carburized, the laser used has a wavelength ranging from 1060nm to 1070nm, a power ranging from 2000W to 4000W, a speed of laser melting ranging from 500mm/min to 20000mm/min, and a spot size ranging from 2mm to 3 mm.

10. A metal workpiece, characterized in that it employs the partial carburization method for a metal workpiece according to any one of claims 1 to 9.

Technical Field

The invention relates to the technical field of heat treatment of metal workpieces, in particular to a local carburizing method for the metal workpieces and the metal workpieces.

Background

Carburization refers to the process of infiltrating carbon atoms into the surface layer of the steel. The low-carbon steel workpiece is provided with a surface layer of high-carbon steel, and the surface layer of the workpiece is subjected to quenching and low-temperature tempering to have high hardness and wear resistance, while the central part of the workpiece still maintains the toughness and plasticity of the low-carbon steel. At present, the commonly adopted carburizing modes are gas carburizing, vacuum carburizing, plasma carburizing and the like.

Vacuum carburization, also known as low-pressure carburization technology, is a process of introducing a carburizing medium, namely high-purity acetylene, into a high-temperature furnace in a pulse mode under a low-pressure (general pressure is 0-30mbar) vacuum state to carry out rapid carburization; the carburizing mode has high cost and high technical threshold, and has higher requirements on the operation and management of a production line. Gas carburization refers to a carburization process performed in a gaseous active medium having a carburizing atmosphere; the carburizing mode has the advantages of complex equipment and higher price. Plasma carburizing is a carburizing method using a glow point in a dilute gas atmosphere; the carburizing method has the advantages of complex process, severe environmental requirement and high cost. Therefore, how to reduce the cost of the carburizing process is an urgent technical problem to be solved.

Disclosure of Invention

In view of the above, the present disclosure provides a method for partially carburizing a metal workpiece and a metal workpiece to solve one or more problems in the prior art.

In accordance with one aspect of the present invention, a method for partial carburization of a metal workpiece is disclosed, the method comprising the steps of:

cleaning the surface to be carburized of the metal workpiece;

mixing carbon powder and alcohol in proportion to form a carburizing agent, and uniformly coating the carburizing agent on the surface to be carburized;

putting the metal workpiece coated with the carburizing agent into a vacuum furnace for drying;

and placing the dried metal workpiece in an inert gas protection environment, and carrying out laser melting or laser sintering on the area to be carburized of the metal workpiece by adopting a laser beam.

In some embodiments of the invention, the mass fraction ratio of the carbon powder to the alcohol is 2: 8.

In some embodiments of the present invention, the carbon powder has a particle size ranging from 10mm to 20 mm.

In some embodiments of the present invention, in the step of drying the metal workpiece coated with the carburizing agent in the vacuum furnace, the drying temperature is 70 ℃ and the drying time is 60 minutes.

In some embodiments of the present invention, the degree of vacuum in the vacuum furnace is 0.5Pa or less.

In some embodiments of the invention, the oxygen content of the inert gas is not greater than 1000 ppm.

In some embodiments of the invention, the metal workpiece is a low carbon steel or a low carbon alloy steel.

In some embodiments of the invention, the method for uniformly coating the carburizing agent on the surface to be carburized is as follows: and immersing the whole metal workpiece into the carburizing agent, taking out and draining.

In some embodiments of the invention, in the step of laser melting or laser sintering the region to be carburized of the metal workpiece, the wavelength of the laser used is 1060nm to 1070nm, the power range is 2000W to 4000W, the speed range of laser melting is 500mm/min to 20000mm/min, and the spot size range is 2mm to 3 mm.

According to another aspect of the invention, a metal workpiece is disclosed that employs the partial carburization method described above.

The local carburizing method for the metal workpiece in the embodiment of the invention adopts the carburizing agent formed by mixing carbon powder and alcohol, and carries out laser melting or laser sintering on the region to be carburized of the metal workpiece through laser beams so as to finish the carburizing process of the metal workpiece; compared with the currently generally adopted carburizing modes such as vacuum carburizing, gas carburizing, plasma carburizing and the like, the method is simple and convenient to operate; the economic cost and the time cost can be effectively reduced; the wear resistance and fatigue strength of the metal workpiece are effectively improved.

Additional advantages, objects, and features of the invention will be set forth in part in the description which follows and in part will become apparent to those having ordinary skill in the art upon examination of the following or may be learned from practice of the invention. The objectives and other advantages of the invention will be realized and attained by the structure particularly pointed out in the written description and claims hereof as well as the appended drawings.

It will be appreciated by those skilled in the art that the objects and advantages that can be achieved with the present invention are not limited to the specific details set forth above, and that these and other objects that can be achieved with the present invention will be more clearly understood from the detailed description that follows.

Drawings

The accompanying drawings, which are included to provide a further understanding of the invention and are incorporated in and constitute a part of this application, illustrate embodiment(s) of the invention and together with the description serve to explain the principles of the invention. The components in the figures are not necessarily to scale, emphasis instead being placed upon illustrating the principles of the invention. For purposes of illustrating and describing some portions of the present invention, corresponding parts of the drawings may be exaggerated, i.e., may be larger, relative to other components in an exemplary apparatus actually manufactured according to the present invention. In the drawings:

FIG. 1 is a flow chart of a method of partial carburization of a metal workpiece according to an embodiment of the present invention.

Detailed Description

In order to make the objects, technical solutions and advantages of the embodiments of the present invention more apparent, the embodiments of the present invention are further described in detail below with reference to the accompanying drawings. The exemplary embodiments and descriptions of the present invention are provided to explain the present invention, but not to limit the present invention.

It should be noted that, in order to avoid obscuring the present invention with unnecessary details, only the structures and/or processing steps closely related to the scheme according to the present invention are shown in the drawings, and other details not closely related to the present invention are omitted.

It should be emphasized that the term "comprises/comprising/comprises/having" when used herein, is taken to specify the presence of stated features, elements, steps or components, but does not preclude the presence or addition of one or more other features, elements, steps or components. It should be noted that the terms of orientation and orientation used in the present specification are relative to the orientation and orientation shown in the drawings.

The local carburizing method for the metal workpiece in the embodiment of the invention comprises the following steps: cleaning the surface to be carburized of the metal workpiece; mixing carbon powder and alcohol in proportion to form a carburizing agent, and uniformly coating the carburizing agent on the surface to be carburized; putting the metal workpiece coated with the carburizing agent into a vacuum furnace for drying; and placing the dried metal workpiece in an inert gas protection environment, and carrying out laser melting or laser sintering on the area to be carburized of the metal workpiece by adopting a laser beam.

The local carburizing method for the metal workpiece has the advantages of simple equipment and simple process, and can be suitable for local carburizing of workpieces with complex curved surfaces.

Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings. In the drawings, the same reference numerals represent the same or similar parts/steps.

Fig. 1 is a schematic flow chart illustrating a method for manufacturing a pre-control segment according to an embodiment of the invention. As shown in fig. 1, the method comprises the steps of:

and S10, cleaning the surface to be carburized of the metal workpiece.

The cleanness of the surface of the workpiece plays an important role in the uniformity of a carburized layer of a carburized product and avoiding soft spots from appearing on the surface hardness after the subsequent process quenching. In the carburization process of the metal workpiece, in order to prevent quality defects such as quenching soft spots, non-uniform hardened layers, non-uniform structures and the like, the impurities such as oxide scales, rust spots, oil stains and the like on the surface to be processed of the metal workpiece are generally required to be cleaned. Oil stains, metal scraps, abrasive and the like on the surface to be processed can be cleaned by an alkali liquor cleaning method; and rust and the like on the surface to be processed can be cleaned by a mechanical cleaning method. It should be understood that, for cleaning the surface of the metal workpiece, the cleaning method is not particularly limited, and may be one of a plurality of cleaning methods, or a combination of the plurality of cleaning methods, as long as it is ensured that the surface to be processed of the workpiece after cleaning is clean, and the natural color of the workpiece matrix is exposed without impurities such as scale, rust, oil stain, etc.

S20: mixing carbon powder and alcohol in proportion to form a carburizing agent, and uniformly coating the carburizing agent on the surface to be carburized of the workpiece.

Carburizing agents are media that, under given conditions, can penetrate carbon into the surface layer of a workpiece and are of various types, such as solid, paste, liquid, and the like. The carburizing agent can be a medium formed by mixing carbon powder and alcohol; the specific substrate of the workpiece may be low carbon steel or low carbon alloy steel. When the workpiece is low-carbon steel, a medium formed by mixing carbon powder and alcohol can be uniformly coated on the surface to be carburized of the low-carbon steel workpiece. It should be understood that the material of the workpiece may be other carburizable materials than low carbon steel or low carbon alloy steel; in addition, the carburizing agent can also be a mixture comprising other types of components, such as carbon powder, alcohol and acetone, mixed according to a predetermined ratio, according to the characteristics of the specific adopted substrate.

In this step, the coating method of the carburizing agent has various methods. For example, the whole workpiece shell can be immersed in the carburizing agent, and then the workpiece is taken out and the carburizing agent on the workpiece is drained. When the carburizing agent is formed by mixing carbon powder and alcohol, the workpiece is immersed in the mixed solution of the carbon powder and the alcohol. It should be noted that the thickness of the carburizing agent affects the quality of the carburized workpiece; for example, if the thickness of the carburizing agent is too thin, a carburized layer is thin, and the phenomenon of surface fatigue and falling is easily caused at the moment; if the carburizing agent coating thickness is too thick, the carburized layer will be too thick, and the impact load resistance of the workpiece will be reduced. Therefore, the thickness of the carburizing agent is preferably controlled to be 0.01mm to 0.1 mm. It should be noted that, in parts with light wear and low contact stress during operation, the carburized layer may be thinner, that is, the thickness of the carburizing agent coated on the surface of the workpiece may take a small value; for some parts with lower carbon content, the carburized layer can be thicker, namely the thickness of the carburizing agent coated on the surface of the workpiece can take a slightly larger value; in particular manufacturing processes, the low carbon alloy steel workpiece may be coated with a carburizing agent that is slightly less than the carburizing agent thickness of the low carbon steel workpiece.

In this step, the mass fraction ratio of carbon powder and alcohol in the carburizing agent may preferably be 2: 8. The proportion not only can ensure the fluidity of the carburizing agent, but also can ensure the dispersion degree of the carburizing agent. The mixing ratio of the carbon powder and the alcohol is only a preferred embodiment, and can be correspondingly changed according to the performance requirement of the metal workpiece and the requirement of the atmosphere protection environment of the metal workpiece in the processing process in the specific carburizing process. In addition, the particle size of the carbon powder in the carburizing agent directly influences the subsequent processing procedure, and preferably, the particle size of the carbon powder adopted by the carburizing agent can be in the range of 10nm to 20 nm.

S30: and putting the metal workpiece coated with the carburizing agent into a vacuum furnace for drying.

After the carburizing agent is uniformly coated on the surface to be processed of the workpiece, the workpiece coated with the carburizing agent needs to be further dried. This is because the carburizing agent formed by mixing carbon powder and alcohol is in a liquid state, and in the subsequent laser melting or laser sintering process, the workpiece coated with the carburizing liquid can be dried first in order to prevent the liquid carburizing agent from affecting the quality of the workpiece due to the flow of the carburizing agent. The drying mode has a plurality of modes, and optionally, a vacuum furnace can be adopted for drying.

When a vacuum furnace is selected for drying, the vacuum degree in the furnace can be below 0.5 Pa. The drying temperature in the furnace can be 70 ℃ at this time, and after drying for 60 minutes, the workpiece is further cooled to room temperature along with the furnace and taken out.

S40: and placing the dried metal workpiece in an inert gas protection environment, and carrying out laser melting or laser sintering on the region to be carburized of the metal workpiece by adopting a laser beam.

After the workpiece coated with the carburizing agent is dried, the workpiece is further placed in an inert gas protection environment to facilitate subsequent processing. Then, the workpiece in the inert gas protective environment is subjected to laser melting or laser sintering on the region to be carburized through the laser beam. The region to be carburized is a partial region of the workpiece that needs to be carburized, which is set in advance according to actual operating requirements, and for example, when the workpiece is a gear, the region to be carburized or the partial carburized region refers to a working surface, i.e., a tooth surface, of the gear. In addition, when the shape of the workpiece is complex, for example, in the case of a case with a gaussian curved surface, the carburized regions may be irregularly distributed, and then, by means of a selective laser melting or selective laser sintering process, after setting a scanning path of a laser beam or modeling according to the distribution of the carburized regions of the workpiece in advance, local carburization of the complex part may be achieved. Therefore, the local carburizing mode can realize the local carburizing treatment of the workpiece with the complex curved surface, and has simple process and low cost.

The laser processing equipment used by the equipment for realizing the selective laser melting process can be a fiber laser, a CO2 laser, a Nd-YAG laser and the like. The wavelength of the fiber laser is 1090nm, that of the Nd-YAG laser 1064nm, and that of the CO2 laser 10640 nm. It should be noted that the absorption of the metal powder is relatively high for shorter wavelength lasers such as 1064nm, and relatively low for longer wavelength lasers such as 10640 nm. Therefore, it is preferable that the wavelength range of the laser processing apparatus used in this step may be 1060nm to 1070 nm.

In addition, in the manufacturing process, the laser power and the melting speed of the laser processing equipment affect the mechanical properties of the workpiece. When the laser power is small, the temperature of a workpiece substrate is low, the power density of a melting unit area is not enough, and the surface is uneven; when the laser power is higher, the power density is higher, the molten pool stirring is serious, the mutual diffusion of matrix elements and carburizing agent elements is serious, the workpiece is over-burnt, and the phenomenon of wrinkles on the surface of the workpiece can be caused; in addition, the porosity of the part is reduced along with the increase of the laser power and the reduction of the melting speed, so that in order to ensure that the workpiece has better mechanical properties, the power range of the selected laser can be 2000W-4000W, and the melting speed range is 500 mm/min-2000 mm/min.

In addition to the above parameters, the spot size on the surface of the workpiece also affects the mechanical properties of the part. For example, the spot size should not be too large, because the energy is concentrated on the upper surface of the workpiece as the diameter of the spot becomes larger under the same energy density, and the powder below the upper surface cannot be effectively melted by the laser molten pool, which directly affects the quality of the part; therefore, in order to further ensure the quality of the workpiece, the spot diameter of the selected laser can be in the range of 2mm to 3 mm.

In an embodiment of the present invention, during a laser melting or laser sintering process of a workpiece with a surface to be processed coated with a carburizing fluid, the workpiece is always in an inert gas protection environment, that is, a processing environment of the workpiece is an inert gas protection environment. It is also understood that the workpiece is subjected to laser melting or laser sintering in an atmosphere protective environment. The inert gas is also called rare gas, which is not decomposed at high temperature, is not easy to generate chemical action on metal, and is not dissolved in the monoatomic gas of liquid metal; the inert gas is specifically helium, neon, argon, krypton, xenon or radon. Therefore, the workpiece is placed in the inert gas environment for selective laser melting or laser sintering, so that the protective gas and the substance are effectively prevented from generating chemical reaction, and the workpiece is further ensured to keep good mechanical property. The workpiece in the inert gas environment has low requirements on the rigidity and the sealing property of the atmosphere protection chamber, the preparation time of the gas protection environment can be reduced, the utilization rate of the inert gas is improved, and the cost is reduced. And further, the oxygen content of the inert gas is not higher than 1000 ppm.

According to another aspect of the present invention, there is also provided a metal workpiece that employs the partial carburization method in the above-described embodiment.

From the above, the local carburization method disclosed by the invention adopts the carburizing agent formed by mixing carbon powder and alcohol, and laser melting or laser sintering is carried out on the region to be carburized of the metal workpiece through laser beams so as to complete the local carburization treatment of the metal workpiece; compared with the currently generally adopted carburizing modes such as vacuum carburizing, gas carburizing, plasma carburizing and the like, the method is simple and convenient to operate; the economic cost and the time cost can be effectively reduced; the wear resistance and the fatigue strength of the workpiece are effectively improved.

Features that are described and/or illustrated with respect to one embodiment may be used in the same way or in a similar way in one or more other embodiments and/or in combination with or instead of the features of the other embodiments in the present invention.

The above-mentioned embodiments illustrate and describe the basic principles and main features of the present invention, but the present invention is not limited to the above-mentioned embodiments, and those skilled in the art should make modifications, equivalent changes and modifications without creative efforts to the present invention within the protection scope of the technical solution of the present invention.