KR20180061699A - Method for laminating tungsten carbide and binder through laser cladding - Google Patents

Abstract

The present invention relates to a method for laminating tungsten carbide and a binder through laser cladding, which comprises the following steps of: preparing tungsten carbide powder and a binder on a plurality of hoppers; and allowing the hoppers to simultaneously spray and laminate the tungsten carbide powder and the binder on a metal surface and then form a cladding layer on the metal surface using a laser cladding technique. Moreover, the binder is A131 powder.

Description

[0001] The present invention relates to a method for laminating tungsten carbide and binder by laser cladding,

The present invention relates to a technique for laminating tungsten carbide (WC) on a surface of metal parts by laser cladding technology using DMT (Laser-aided Direct Metal Tooling) equipment, The present invention relates to a technique for simultaneously laminating A131 powder, which is a metal material that can act as a binder, in order to prevent defects such as cracks and pores in the material.

Laser cladding technology creates a new cladding layer with a completely different chemical composition and microstructure on the metal surface in order to impart surface properties such as abrasion resistance, corrosion resistance, heat resistance and erosion resistance to the surface of metal parts It is a kind of coating technology.

Laser cladding technology irradiates a high-power laser beam on a metal surface to instantly create a melt pool, and at the same time supplies materials such as metal, alloy, and ceramic, which are powdered cladding materials from the outside, Or a laser surface modification technique to form a new cladding layer having different chemical composition and microstructure.

Since the metal cladding layer and the cladding layer are metallically fusion-bonded, the bonding between the cladding layer and the surface of the cladding layer is extremely superior to other surface treatment techniques. It is possible to form a cladding layer having a thickness of 0.1 to 2 mm.

In general, the microstructure of commercial tungsten carbide (WC), which is generally applied, has a structure in which cobalt (Co) is entangled between tungsten carbide powders in the microstructure of tungsten carbide made of powder metallurgy. Tungsten carbide is an alloy with high hardness and toughness. It has excellent abrasion resistance and is used for cutting tools, dies, etc. Mostly, it is made of powder metallurgy. In addition, tungsten carbide is laminated on the functional part to ensure high hardness and economical product production.

Conventionally, tungsten carbide has a high hardness and is subject to cracking due to melting and quenching. As a result, defects such as cracks and pores are generated in the laminated material during lamination.

Prior art documents suggesting sintering using tungsten carbide or cladding and fusion welding of superalloys include Korean Patent No. 10-1215656 (Jan. 01, 2013) and Korean Patent Laid-open No. 10-2015-0088181 .31) can be referred to.

(Patent Document 1) KR10-1215656 B

(Patent Document 2) KR10-2015-0088181 A

Disclosure of Invention Technical Problem [8] Accordingly, the present invention has been made to solve the above-mentioned problems, and it is an object of the present invention to provide a technique of simultaneously forming a cladding layer on a metal surface by using laser cladding technology, and simultaneously spraying and laminating tungsten carbide and a binder on a metal surface The purpose is.

 That is, the present invention uses a plurality of hoppers constituting a powder feeder of the DMT equipment, and A131 powder is charged as a metal material to serve as a binder through the first hopper among the plurality of hoppers, And simultaneously tungsten carbide powder is injected through the second hopper and laminated.

According to an aspect of the present invention, there is provided a method of laminating a tungsten carbide and a binder through laser cladding, the method comprising: preparing a tungsten carbide powder material and a binder on a plurality of hoppers; And simultaneously spraying and laminating the tungsten carbide powder material and the binder on the metal surface in the plurality of hoppers and forming a cladding layer on the metal surface using a laser cladding technique, A131 powder.

The tungsten carbide and the binder commonly include Cr, Fe, and C, respectively.

The powder size of the tungsten carbide powder material is from 37 탆 to less than 90 탆.

The powder size of the binder is 45 탆 or more and less than 150 탆.

The method of laminating the tungsten carbide and the binder through the laser cladding according to the present invention as described above can be similar to that of adding an alloy to tungsten carbide in the past, but it is difficult to obtain a tungsten carbide and a binder by maintaining the characteristics such as abrasion resistance and hardness which are fundamental properties of tungsten carbide There is an advantage that process conditions for preventing the occurrence of defects such as cracks and pores in laser cladding are set.

Further, the present invention can be manufactured more economically using A131 powder, which is a low alloy steel which is lower in cost than nickel and cobalt based alloys.

By replacing the product made through the existing sintering process, the laser cladding process enables tungsten carbide to be laminated only on the functional parts of the product, securing high hardness and producing economical products.

1 illustrates the concept of a 3D metal printer that performs laser cladding according to the present invention.
FIGS. 2 and 3 show the cross-section and internal structure of a cladding layer stacked by supplying tungsten carbide and A131 powder onto a metal specimen according to the present invention.
FIGS. 4A and 4B are test results on a laminated structure of tungsten carbide and a binder formed through laser cladding according to the present invention. FIG.

Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings. It should be understood, however, that the invention is not limited to the disclosed embodiments, but is capable of other various forms of implementation, and that these embodiments are provided so that this disclosure will be thorough and complete, It is provided to let you know completely. Wherein like reference numerals refer to like elements throughout.

It should be noted that, in adding reference numerals to the constituent elements of the drawings, the same constituent elements are denoted by the same reference symbols as possible even if they are shown in different drawings. In the following description of the present invention, a detailed description of known functions and configurations incorporated herein will be omitted when it may make the subject matter of the present invention rather unclear.

In describing the components of the present invention, terms such as first, second, A, B, (a), and (b) may be used. These terms are intended to distinguish the constituent elements from other constituent elements, and the terms do not limit the nature, order or order of the constituent elements. When a component is described as being "connected", "coupled", or "connected" to another component, the component may be directly connected or connected to the other component, Quot; may be "connected," "coupled," or "connected. &Quot;

Hereinafter, a method of laminating tungsten carbide and a binder through laser cladding according to the present invention will be described with reference to FIGS. 1 to 4. FIG.

In the present invention, DMT (Direct Metal Tooling) 3D metal printing can be applied by a 3D metal printing method. DMT 3D metal printing technology is a new concept of 3D metal printing technology that can quickly produce complex shapes of metal products and molds from 3D CAD data by melting metal powder using high power laser beam. Unlike other 3D metal printers, which are classified as 'Powder Bed Fusion' technology, DMT 3D metal printing technology is very economical because it uses inexpensive general industrial metal powder directly and supplies metal powder in real time during printing process. Since the metal powder is completely melted and rapidly solidified by laser beam irradiation during the printing process, a metal product having almost 100% dense and fine structure is produced. In most cases, the manufactured metal product is the same or better than the forging material Mechanical properties.

In 3D printing technology, a three-dimensional shape is composed of two-dimensional cross-sections, and a three-dimensional shape is created by slicing a 3D CAD model to a constant thickness and physically stacking the two-dimensional cross sections calculated therefrom.

In DMT 3D metal printing, the metal layer corresponding to a two-dimensional cross-section is made of a high-power laser and metal powder. When a high-power laser beam is locally irradiated onto a metal surface, a molten pool is instantly generated on the metal surface, Controlled metal powder in real time. The metal powder is completely melted and rapidly solidified in the molten pool. The laser beam or the metal specimen is moved forward, backward, leftward and rightward according to the tool path calculated from the 3D CAD model to form a metal layer corresponding to a two- Repeat one process in a layer-by-layer fashion to print the same metal product as the 3D CAD model.

Referring to FIG. 1, a 3D metal printer for performing laser cladding according to the present invention includes a substrate 10, a powder supply unit 20 for supplying metal powder onto the substrate 10, And a metal specimen 30 on which lamination is carried out.

The powder feeder 20 may include a plurality of hoppers.

A cladding layer is formed on the surface of the metal specimen 30 by using a laser cladding technique simultaneously with tungsten carbide and binder in a plurality of hoppers.

In the present invention, A131 powder is used as the metallic material functioning as a binder.

That is, A131 powder is supplied from the first hopper among the plurality of hoppers, and tungsten carbide (WC) is injected from the second hopper among the plurality of hoppers to be stacked.

A131 is the ASTM standard for steel plates for hull structural steel, and is a standard for plate, shape, and bar, and general steel grades A, B, D and E GRADE. High strengths include AH, DH, EH, and FH grade. The charpy V-notch impact test temperature varies depending on the grade.

A131 is a low-carbon steel, which has a good elongation of about 25% when laminated with DMT equipment. Therefore, it is preferable to serve as a binder when laminating tungsten carbide having high brittleness. In addition, the cost of A131 powder material is low, which is economical.

Table 1 below shows specific constituents and content of tungsten carbide and A131 powder supplied through a plurality of hoppers, respectively.

Powder Co CMnV Cr Fe W Mn Cu Si Ni Powder size (탆) WC 12.6 5.46 0.096 Honey. 37 탆 or more and less than 90 탆 A131 0.18 0.5 Honey. 0.9 to 1.6 0.35 0.1 to 0.5 0.4 45 μm or more and less than 150 μm

In Table 1, the unit of content of tungsten carbide and A131 is wt%. Bal stands for balance.

Table 2 below shows the condition that tungsten carbide and A131 powder are supplied on the metal specimen 30 to be laminated.

No Powder Disk (%) Laser
Power (W) Gas (l / min) Scan speed (mm / min) Defocusing
(mm) WC A131 Powder Shield One 30 30 500 2 3 850 +2 2 30 20 500 2 3 850 +2 3 20 35 900 2 3 850 +2

Table 3 below shows the Vickers hardness of the result according to the degree of WC powder inside the bead on the single bead cross section.

That is, the optimal process conditions are selected through the process condition experiment and the hardness is measured. Specifically, the hardness of the tungsten carbide powder was compared with the hardness of the first condition among the three conditions, and the distribution of the tungsten carbide in the bead was most uniform.

No Bead inside
WC powder One 2 3 Single Bead
section

Hv (0.1 kgf) 1414.9 1074.8 793 664.1

2 and 3, a laminated structure of tungsten carbide and binder formed through laser cladding according to the present invention will be described.

First, it can be confirmed that the interface between the substrate and the cladding is clean without cracks and defects, and there is no defect inside the cladding.

Next, the cross-section shows that the tungsten carbide is embedded and the remaining structure is formed of a new structure while the tungsten carbide is melted on the A131.

Referring to FIG. 4, a test report on a laminated structure of tungsten carbide and a binder formed through laser cladding according to the present invention will be described.

The internal structure of the Vickers hardness was measured at an average of 1088 Hv.

In the conventional case, a tungsten carbide powder is mixed with a Ni-based or a Co-based alloy to improve the abrasion resistance and hardness, and laser cladding is performed to form a surface layer. In this case, the hardness of the surface layer is about 1700 HV, which is the hardness of tungsten carbide The present invention solves the problem that there is a limitation in showing only a hardness value of 500 to 700 HV which is slightly higher than the original material.

As described above, the method of laminating the tungsten carbide and the binder through the laser cladding according to the present invention can be similar to that of adding the alloy to the tungsten carbide in the past. However, in the case of maintaining the properties such as abrasion resistance and hardness which are fundamental properties of tungsten carbide There is an advantage that process conditions for preventing the occurrence of defects such as cracks and pores in laser cladding are set.

It is to be understood that the terms "comprises", "comprising", or "having" as used in the foregoing description mean that the constituent element can be implanted unless specifically stated to the contrary, But should be construed as further including other elements. All terms, including technical and scientific terms, have the same meaning as commonly understood by one of ordinary skill in the art to which this invention belongs, unless otherwise defined. Commonly used terms, such as predefined terms, should be interpreted to be consistent with the contextual meanings of the related art, and are not to be construed as ideal or overly formal, unless expressly defined to the contrary.

The foregoing description is merely illustrative of the technical idea of the present invention, and various changes and modifications may be made by those skilled in the art without departing from the essential characteristics of the present invention. Therefore, the embodiments disclosed in the present invention are intended to illustrate rather than limit the scope of the present invention, and the scope of the technical idea of the present invention is not limited by these embodiments. The scope of protection of the present invention should be construed according to the following claims, and all technical ideas within the scope of equivalents should be construed as falling within the scope of the present invention.

Claims (4)

CLAIMS 1. A method for cladding a tungsten carbide powder material onto a metal part using a laser,
Preparing a tungsten carbide powder material and a binder on a plurality of hoppers, respectively; And
Forming a cladding layer on the metal surface by using a laser cladding technique, and simultaneously forming a cladding layer on the metal surface by spraying and laminating the tungsten carbide powder material and the binder on the metal surface simultaneously in the plurality of hoppers,
The binder is A131 powder,
Method of laminating tungsten carbide and binder through laser cladding.
The method according to claim 1,
Wherein the tungsten carbide and the binder commonly include Cr, Fe, and C,
Method of laminating tungsten carbide and binder through laser cladding.
The method according to claim 1,
Wherein the powder size of the tungsten carbide powder material is not less than 37 [mu] m and less than 90 [
Method of laminating tungsten carbide and binder through laser cladding.
The method according to claim 1,
Wherein the powder has a powder size of 45 mu m or more and less than 150 mu m,
Method of laminating tungsten carbide and binder through laser cladding.

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