KR20060044439A - Hard metal-cored hardfacing welding wire for improved impact wear resistance - Google Patents

Abstract

The present invention is to manufacture a metal-cored weld wire using a powder and iron-based strips mixed with austenitic stabilizing elements added to cemented carbide powder having a tungsten carbide content of 50 ~ 90 wt.%, The effective of tungsten carbide in the wire The content is 22.5 ~ 30.0 wt% and the content of austenite stabilizing elements such as Mn, C, etc. is characterized in that 0.05 ~ 0.2 wt% Ni equivalent.

The growth welding layer hard-faced by the welding wire is characterized by a sub-process microstructure consisting of a 10-25 vol% tungsten carbide dispersed phase and a matrix containing austenite as a main component, and having a hardness of 40-50 HRC, but with an appropriate amount. Due to the hardened dispersed phase and the austenitization of the matrix, it shows excellent impact resistance along with abrasion resistance.

Weld Welding, Hard Facing, Welding Wire, Metal Cored, Tungsten Carbide, Austenitic Stabilizing Elements, Wear Resistance, Impact Resistance

Description

Carbide-cored welded wire with excellent impact wear resistance {HARD METAL-CORED HARDFACING WELDING WIRE FOR IMPROVED IMPACT WEAR RESISTANCE}

1 is a schematic view for explaining a manufacturing process of the welding wire according to an embodiment of the present invention;

FIG. 2 is a schematic view for explaining a process of forming a growth welding layer using the welding wire manufactured by the process of FIG. 2;

Figure 3 is a graph showing the wear loss of the growth welding layer according to the effective content of tungsten carbide when the growth welding layer is formed using a welding wire containing tungsten carbide;

4 is a graph showing the amount of grinding wear of the welding wire and other comparative products according to an embodiment of the present invention; And

5 is a graph showing the impact wear loss of the welding wire and other comparative products according to an embodiment of the present invention.

<Description of Symbols for Main Parts of Drawings>

10: Tungsten Carbide Carbide Alloy

20: Tungsten Carbide Cemented Carbide Powder

30: mixed powder 40: iron strip

50: welding wire 60: non-consumable tungsten electrode

70: base material 80: growth welding layer

The present invention relates to a cemented carbide welded wire with improved impact abrasion resistance. It relates to a metal cored welding wire for facing.

In order to prolong the life of mechanical parts used in the severe abrasion environment, hardfacing is a technology that fosters and welds abrasion-prone parts with high wear resistance.

In general, high-facing high-carbon iron-based welding materials are used for hardfacing mechanical parts requiring high wear resistance, in which iron (Fe) is used as a base material and chromium carbide (CrC) is used in a dispersed phase. It has a high hardness of over 60 HRC due to the over-processing composition containing about 3% chromium and 3 ~ 6 wt% carbon. However, due to the high alloying element content, cracks are severely generated in the growth welding layer. Have Table 1 shows a composition example table and hardness of the welding material for the major iron-based hardfacing currently in the market.

product C Mn Si Cr Co Mo V W Nb Hardness W company Product A 1.80 1.00 1.20 34.00 1.00 35-40 Product B 5.00 3.00 1.80 27.00 60-62 Product C 5.50 2.00 1.60 23.00 7.00 1.50 2.00 7.00 63-67 Product D 60.00 60-65 H company Product A 6.10 1.80 0.50 25.00 60-62 Product B 0.43 16.00 0.56 10.90 50-55 Product C 0.90 1.90 1.50 7.50 1.90 2.50 0.90 4.80 3.90 54-56 Product D 4.80 1.65 1.60 25.00 1.00 58-62

Competitive in terms of price, chromium carbide-based welding materials contain high amounts of chromium in order to meet the required hardness, which not only provides the cause of the large cracks in the welding layer but also the large amount of the welding process. Provides a source of toxic chromium (Cr) vapors.

In addition, chromium is not only a carcinogen that can cause laryngeal cancer and lung cancer, but also an element known to cause industrial accidents such as nasal septum perforation in the cartilage of the nasal cartilage. There is a growing international interest in.

In addition, the metal-cored welded wire manufactured using cemented carbide powder alone shows excellent grinding wear resistance, but the type of carbide formed is W ₆ C type, which has lower strength and toughness than WC type, and some martensite phase is present on the matrix. It is difficult to apply in extreme impact wear environment.

Accordingly, an object of the present invention is to solve the above problems, by using a tungsten carbide contained in a large amount of cemented carbide powder as a high hardness dispersed phase, showing excellent grinding wear resistance and at the same time economically increased resistance to impact wear To provide a phosphorous carbide cored welding wire.

Another object of the present invention is to provide a cemented carbide welded wire, which can significantly reduce the manufacturing cost by recycling the discarded cemented carbide as an alloying element of the welding wire for hard facing.

In order to achieve the above objects, the cemented carbide welded wire with excellent impact abrasion resistance according to the present invention is Ni and austenitic stabilizing elements Mn and C in tungsten carbide-based cemented carbide powder having a content of tungsten carbide 50 ~ 90wt% Ni After mixing 0.05 to 0.2 wt% in equivalent weight and filling into the iron strip with the welding flux, the effective content of tungsten carbide in the entire welding wire is prepared to have a range of 22.5 to 30.0 wt%.

For arc stabilization and spatter reduction, any one selected from Ca-Titanate, TiO ₂ , Na compounds and K compounds is further added.

In order to suppress weld pores and defects, it is further characterized by adding any one selected from Al, Mg and Zr.

Hereinafter, a cemented carbide cored welding wire according to various embodiments of the present disclosure will be described in detail with reference to the accompanying drawings. The following examples are only presented to understand the content of the present invention, and those skilled in the art will be capable of many modifications within the technical spirit of the present invention. Accordingly, the scope of the present invention should not be construed as being limited to these embodiments.

The hard-facing welding wire according to the present invention is manufactured as a metal-cored welding wire having a filling rate of 20 to 50 wt% using a cemented carbide powder and iron-based strip containing tungsten carbide in an amount of 50 to 90 wt%. The manufacturing method is shown in FIGS. 1 and 2.

1 and 2 are views for explaining a method for forming a welding wire and a growth welding layer according to an embodiment of the present invention. First, a tungsten carbide-based cemented carbide powder 20 is formed using a tungsten carbide-based cemented carbide alloy 10. (Step b). Tungsten carbide-based cemented carbide 10 contains a small amount of components such as Co, C, Nb. In order to reduce the manufacturing cost, it is preferable to use the tungsten carbide-based cemented carbide 10 that is already discarded.

Next, the Fe-strip 40 is curled while the tungsten carbide-based cemented carbide powder 20 is mixed with the austenitic stabilizing element Mn and C 30 onto the Fe strip 40, and the Fe-strip 40 is rolled up. The Fe strip 40 is drawn to be (d step). Then, as in step e, the mixed powder 30 is completed as a welding wire 50 formed by filling the Fe strip in the form of a tube as the welding metal flux 30a. The completed welding wire 50 is applied to the surface of the substrate 70 through a gas tungsten arc (GTA) welding method using a non-consumable tungsten electrode 60 or a gas metal arc (GMA) welding method using a wire as a consumable electrode. When the growth welding, the growth welding layer 80 is formed (step g).

In the manufacturing process as described above, the cemented carbide powder prepared by grinding the cemented carbide parts is mixed with other materials in the manufacturing process, the content of tungsten carbide as the main component is about 50 ~ 90 wt%.

In the case of metal-cored wire manufactured using cemented carbide powder only, the growth welding layer has a matrix of austenite and martensite mixed. If the brittle martensite component is removed to form a complete austenite phase, the impact abrasion resistance is improved. Can be.

To achieve a complete austenite phase, austenite stabilizing elements can be added to expand the austenite region in iron alloys. These elements include Ni, Co, Mn, Cu, N, and C. It may be expressed in Ni equivalents.

Ni equivalent = (Ni) + (Co) + 0.5 (Mn) + 0.3 (Cu) + 25 (N) + 30 (C)

Here, (Ni), (Co) and the like represent the wt% of the element and Ni equivalent is also expressed as wt%.

Among them, Ni plays a role of lowering the wear resistance of the alloy, Co is expensive, and economic efficiency is deteriorated. Cu and N have low solubility, so that the effect of addition is insignificant, and Mn and C can be effective addition elements.

The results of observing the abrasive wear loss of the welded portion according to the effective content of tungsten carbide is shown in FIG. As shown in FIG. 3, the lowest wear loss shows that the effective content of tungsten carbide in the entire welding wire is 22.5 to 33.3 wt%, but in order to manufacture the metal cored wire by adding austenite stabilizing elements, the effective content is 30. It should be adjusted to wt% or less.

As a result of examining the microstructure change and the grinding wear resistance according to the amount of Mn and C addition, the total austenite matrix was formed only when the Ni equivalent was 0.05 wt% or more, and when the Ni equivalent was more than 0.2 wt%, the carbide formation was too reduced to decrease the wear resistance. Results.

As mentioned above, the main object of the present invention is to produce a welding wire excellent in impact wear resistance even if the grinding wear resistance is somewhat inferior.

Figure 4 is a graph showing the abrasive wear loss amount of the welding wire and other products according to the invention, Figure 5 is a graph showing the impact wear loss amount of the welding wire and other products according to the present invention, these results are shown in Table 2 below It was.

WC 30wt% (Comparative) WC 30wt% + (Ni) 0.2wt% (invention) Company A CrC Products (Comparative Products) Grinding wear loss (mg) 35 48 65 Impact Wear Loss (mg) 0.5 0.1 15.7

4 and 5, the product of WC 30wt% is a metal cored welding wire having an effective content of tungsten carbide 30wt%, WC 30wt% + (Ni) 0.2wt% of the product According to the welding wire according to the WC 30wt% Ni equivalent to Mn and C added 0.2wt% added to the metal cored welding wire, Company A WC products and CrC products are A company's pure tungsten carbide powder filled products and chromium Carbide filling products. As can be seen from Table 2, it can be clearly seen that the grinding wear loss increases slightly but the impact wear loss decreases as the austenitic stabilizing element is added to the metal cored wire filled with cemented carbide powder.

Such products are suitable for use in places where high impact wear resistance is required.

Meanwhile, a flux component for improving welding workability may be added to the metal cored wire at less than 1 wt.% Regardless of the wear resistance of the weld. Flux components that can be added include Ca-Titanate, TiO ₂ , Na compounds, and K compounds for arc stability and spatter reduction, and Al, Mg, Zr, etc. for suppressing weld pores and defects.

Therefore, when welding using the welding wire prepared according to the present invention, it is possible to obtain a growth welding layer having a sub-process microstructure consisting of a 10-25 vol% tungsten carbide dispersed phase and a matrix containing austenite as a main component.

As described above, according to the present invention, the tungsten carbide dispersed metal cored welding wire using austenite stabilizing elements added to the cemented carbide powder obtained by crushing the cemented carbide waste parts is inexpensive and has excellent abrasive wear resistance. It is possible to produce a hardfacing welding material having resistance.

The present invention can be utilized as a hardfacing material having excellent grinding wear resistance and impact abrasion resistance, especially for parts that are excessively damaged due to impact, such as crushing rolls in the cement industry, excavation equipment in the mining and dredging industries, and heavy construction equipment. Can be.

Claims (3)

Tungsten carbide cemented carbide powder containing 50 ~ 90wt% of tungsten carbide is mixed with austenite stabilizing elements Mn and C at 0.05 ~ 0.2wt% of Ni equivalent, and then filled into the iron strip together with the welding flux. A cemented carbide welded wire with excellent impact abrasion resistance, characterized in that it is manufactured so as to have an effective content of tungsten carbide in the range of 22.5 to 30.0 wt%.  The method of claim 1, In order to stabilize the arc and reduce spatter, the metal-cored welding wire for hardfacing, characterized in that further addition of any one selected from Ca-Titanate, TiO ₂ , Na compound and K compound.  The method of claim 1, The metal-cored welding wire for hardfacing, characterized in that the addition of any one selected from Al, Mg and Zr to further suppress the weld pores and defects.

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