WO2022065648A1

WO2022065648A1 - Flux cored wire

Info

Publication number: WO2022065648A1
Application number: PCT/KR2021/008946
Authority: WO
Inventors: 장종훈; 박준영; 강문찬
Original assignee: 고려용접봉 주식회사
Priority date: 2020-09-25
Filing date: 2021-07-13
Publication date: 2022-03-31
Also published as: KR102302988B1

Abstract

An embodiment of the present invention provides a flux cored wire having a flux charged inside an alloy-type steel sheath thereof, wherein the sheath comprises, relative to the total weight of the wire, 0.001-0.06 wt% of C, 0.02 wt% or less (excluding 0 wt%) of P+S, 0.01-0.80 wt% of Si, 0.01-3.0 wt% of Mn, 0.01-3.5 wt% of Ni, 0.01-18.0 wt% of Cr, 0.01-1.0 wt% of Mo, and the balance being Fe, oxides, and inevitable impurities; and wherein the flux comprises, relative to the total weight of the wire, 0.08 wt% or less (excluding 0 wt%) of C, 0.01-1.5 wt% of Si, 0.01-3.0 wt% of Mn, 0.50 wt% or less (excluding 0 wt%) of Al, 0.1-1.0 wt% of Mg, 0.01-5.0 wt% of Ti, 0.02-1.0 wt% of Zr, 0.01-4.0 wt% of Ni, 0.01-1.0 wt% of Mo, 0.01-18 wt% of Cr, and the balance being Fe, oxides, and inevitable impurities.

Description

flux cored wire

The present invention relates to a flux-cored wire, and more particularly, to a flux-cored wire that uses a steel sheath containing alloy components to prevent segregation, stabilizes low-temperature toughness, and improves quality uniformity, defect resistance and crack resistance It's about wires.

In general, a flux-cored welding (FCW) method is a welding method that has the highest welding productivity and is easy to weld in various positions. The flux-cored wire used in this welding method means a welding wire in which the flux is filled in the core cavity of a hoop formed in the longitudinal direction.

Looking at the process of forming the flux-cored wire roughly, a hoop having a certain thickness and width is machined to form a U-shape, and a flux of a predetermined component is injected into the center of the hoop. After injecting the flux, make the U-shaped hoop completely surround the flux to complete the primary semi-finished product. By making the semi-finished product have a desired diameter through a wire drawing process, the final flux-cored wire is completed, and welding is performed using this semi-finished product.

The conventional flux-cored wire was produced in the form of mixing and injecting a flux having about 10 to 20 kinds of particles into a hoop having almost no alloy components. That is, flux cored wire is produced by supplementing the flux into the hoop in the form of powder for the purpose of forming slag to have an electric charge or overhead function, or for generating gas or for facilitating welding workability. did

At this time, since about 15 fluxes have different particle shapes, apparent densities, sizes, shapes, etc., they are not completely uniformly mixed even after blending. Segregation occurs in the process of filling the hoop from In addition, fine segregation occurs inside the wire as the flux is crushed while the piped wire is processed into a final product through drawing.

In addition, flux-cored wire is difficult to apply to important structures because of its large metallurgical deviation due to segregation compared to sheathed rods or SAW, which are other welding processes that use flux. There are problems such as problem, lateral crack problem, CTOD property deviation, and the like.

Therefore, there is a need for a method to fundamentally eliminate segregation generated during the process of mixing the flux or filling the hoop with the major alloying elements affecting the low-temperature impact value or mechanical properties.

선행기술문헌Prior art literature

(Patent Document 1) Korean Patent Publication No. 10-0821426 (2008.04.03)

The present invention is to solve the problems of the prior art described above, and an object of the present invention is to prevent segregation by using a steel shell containing an alloy component, thereby stabilizing low-temperature toughness, uniformity of quality, defect resistance and cracking resistance It is to provide this improved flux cored wire.

In order to achieve the above object, one aspect of the present invention is a flux-cored wire filled with flux inside an alloy-type steel sheath, wherein the sheath is based on the total weight of the wire, C: 0.001 to 0.06% by weight, P +S: 0.02% by weight or less (excluding 0% by weight), Si: 0.01 to 0.80% by weight, Mn: 0.01 to 3.0% by weight, Ni: 0.01 to 3.5% by weight, Cr: 0.01 to 18.0% by weight, Mo: 0.01 to 1.0% by weight, the balance contains Fe, oxides and unavoidable impurities, the flux is based on the total weight of the wire, C: 0.08% by weight or less (excluding 0% by weight), Si: 0.01 to 1.5% by weight, Mn: 0.01 -3.0 wt%, Al: 0.50 wt% or less (excluding 0 wt%), Mg: 0.1 to 1.0 wt%, Ti: 0.01 to 5.0 wt%, Zr: 0.02 to 1.0 wt%, Ni: 0.01 to 4.0 wt%, Mo: 0.01 to 1.0% by weight, Cr: 0.01 to 18% by weight, the balance Fe, oxides and unavoidable impurities are included, to provide a flux-cored wire.

In one embodiment of the present invention, it may be a flux-cored wire, characterized in that P+S ≤ 400 ppm while satisfying S ≤ 200 ppm, based on the total weight of the wire in order to minimize cracking in the weld zone.

In one embodiment of the present invention, with respect to the particle size of the final product of the flux filled inside the shell, the flux particle size (α): 5 μm or less Total ≤ 40 wt% (excluding 0 wt%), flux particle size (β): It may be a flux-cored wire, characterized in that the sum of 60 μm or less ≤ 80% by weight, and the flux particle size (γ: the total of 1,000 μm or less = 100% by weight).

In one embodiment of the present invention, in order to prevent welding defects and reduce the amount of diffusible hydrogen, the total moisture content of the wire is 500ppm (excluding 0% by weight) or less based on the total weight of the wire, It can be a flux-cored wire there is.

According to one aspect of the present invention, segregation is prevented, low-temperature toughness is stabilized, and quality uniformity, defect resistance and crack resistance are improved by using a steel sheath containing an alloy component and controlling the composition of the sheath and the flux. can be improved

It should be understood that the effects of the present invention are not limited to the above-described effects, and include all effects that can be inferred from the configuration of the invention described in the detailed description or claims of the present invention.

Figure 1 (a) is a plan view showing the conditions at the time of the crack resistance test.

Figure 1 (b) is a cross-sectional view of Figure 1 (a).

Hereinafter, the present invention will be described with reference to the accompanying drawings. However, the present invention may be embodied in several different forms, and thus is not limited to the embodiments described herein. And in order to clearly explain the present invention in the drawings, parts irrelevant to the description are omitted, and similar reference numerals are attached to similar parts throughout the specification.

Throughout the specification, when a part is "connected" with another part, this includes not only the case where it is "directly connected" but also the case where it is "indirectly connected" with another member interposed therebetween. . In addition, when a part "includes" a certain component, this means that other components may be further provided without excluding other components unless otherwise stated. In addition, unless otherwise specified, % means weight %, and 1 ppm is 0.0001 weight %.

Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings.

The flux-cored wire according to an embodiment of the present invention is a flux-cored wire in which a flux is filled inside an alloy-type steel sheath, wherein the sheath is based on the total weight of the wire, C: 0.001 to 0.06% by weight, P+ S: 0.02% by weight or less (excluding 0% by weight), Si: 0.01 to 0.80% by weight, Mn: 0.01 to 3.0% by weight, Ni: 0.01 to 3.5% by weight, Cr: 0.01 to 18.0% by weight, Mo: 0.01 to 1.0 % by weight, including Fe, oxides and unavoidable impurities as the balance, and the flux is based on the total weight of the wire, C: 0.08% by weight or less (excluding 0% by weight), Si: 0.01 to 1.5% by weight, Mn: 0.01 to 3.0 wt%, Al: 0.50 wt% or less (excluding 0 wt%), Mg: 0.1 to 1.0 wt%, Ti: 0.01 to 5.0 wt%, Zr: 0.02 to 1.0 wt%, Ni: 0.01 to 4.0 wt%, Mo : 0.01 to 1.0% by weight, Cr: 0.01 to 18% by weight, the balance contains Fe, oxides and unavoidable impurities.

The alloying elements constituting the outer shell of the above-described flux-cored wire are as follows with respect to the total weight of the wire, and the content of each alloying element is expressed as a weight ratio.

C: 0.001 to 0.06 wt%

Carbon (C) is an element that improves strength by forming carbides, and is an element added to make the weld heat-affected zone have properties similar to those of the base material. If the C content is less than 0.001 wt %, the effect may not be sufficiently obtained, and thus the proof strength of the weld metal may be reduced. On the other hand, when the C content is more than 0.06% by weight, problems such as breakage during the drawing process may occur due to high strength or work hardening. In addition, there is a disadvantage that low-temperature cracking of the weld joint occurs or the impact toughness is lowered, and a number of heat treatments must be performed due to high hardness to be able to process into a desired final product. Accordingly, the C content may be 0.001 to 0.06% by weight.

P+S: 0.02% by weight or less (excluding 0% by weight)

Phosphorus (P) is an element that improves strength and hardness by causing solid solution strengthening while being present as a solid solution element in steel. If the content of P is too small, it may be difficult to maintain a certain level of rigidity. If the P content is too large, center segregation may occur during casting and ductility may be lowered, which may deteriorate wire workability. Sulfur (S) combines with manganese in steel to form non-metallic inclusions and becomes a factor of red shortness, so it is desirable to lower the content as much as possible. Therefore, therefore, the P+S content may be 0.02 wt% or less (excluding 0 wt%).

Si: 0.01 to 0.80 wt%

Silicon (Si) is an element that improves strength by solid solution strengthening. Such Si prevents oxidation during welding and enables solid solution strengthening to increase the strength of the material. Here, when the Si content is too small, sufficient strength cannot be secured, and when the Si content is excessive, toughness may decrease. Accordingly, the Si content of the shell may be 0.01 to 0.80 wt%.

Mn: 0.01 to 3.0 wt%

In the case of manganese (Mn), as a solid solution strengthening element, it serves to increase the strength of steel and improve hot workability. However, if the Mn content is excessive, the ductility is lowered and it acts as a factor in the occurrence of center segregation, which may cause disconnection during the drawing operation in the welding electrode manufacturing process. If the Mn content is too small, sufficient strength may not be secured, and it may become a cause of red hot brittleness. Accordingly, the Mn content of the skin may be 0.01 to 3.0% by weight.

Ni: 0.01 to 3.5 wt%

Nickel (Ni) is not only effective in improving ductility to improve drawing processability, but also forms a stable structure even at cryogenic temperatures and is a necessary element to improve low-temperature impact properties. If the Ni content is too small, it may be difficult to obtain such an effect, and it may be difficult to stably operate the flux composition. On the other hand, if the Ni content is excessive, the drawability may deteriorate due to an increase in strength, and surface defects may be caused. Accordingly, the Ni content may be 0.01 to 3.5 wt%.

Cr: 0.01 to 18.0 wt%

Chromium (Cr) is an element beneficial to the strength of the weld joint and also serves to form a stable rust layer, thereby contributing to the improvement of corrosion resistance. If the Cr content is too small, it may be difficult to sufficiently exhibit the above-described effect. On the other hand, if the Cr content is excessive, chromium-based carbides may be formed and cause brittleness, which may cause a problem in that processing cannot be performed. Therefore, the Cr content may be 0.01 to 18.0% by weight.

Mo: 0.01 to 1.0% by weight

Molybdenum (Mo) is an advantageous element in terms of securing the strength of the weld joint by increasing hardenability. If the Mo content is too small, it may be difficult to obtain such an effect. If the Mo content is excessive, the formation amount of molybdenum carbide may increase to cause brittleness, which may cause a problem in that workability is deteriorated. Accordingly, the Mo content may be 0.01 to 1.0% by weight.

The alloying elements constituting the flux of the above-described flux-cored wire are as follows with respect to the total weight of the wire, and the content of each alloying element is expressed by weight ratio.

C: 0.08% by weight or less (excluding 0% by weight)

Carbon (C) is an element that improves strength by forming carbides, and is an element added to make the weld heat-affected zone have properties similar to those of the base material. When the C content is too small, sufficient strength cannot be secured. On the other hand, when the C content is more than 0.08 wt %, problems such as disconnection may occur during the drawing process due to high strength or work hardening. Accordingly, the C content may be 0.08% by weight or less.

Si: 0.01 to 1.5 wt%

Silicon (Si) is an element that improves strength by solid solution strengthening. Such Si prevents oxidation during welding and enables solid solution strengthening to increase the strength of the material. Here, when the Si content is too small, sufficient strength cannot be secured, and when the Si content is excessive, toughness may decrease. Accordingly, the Si content of the flux may be 0.01 to 0.80 wt %.

Mn: 0.01 to 3.0 wt%

In the case of manganese (Mn), as a solid solution strengthening element, it serves to increase the strength of steel and improve hot workability. However, if the Mn content is excessive, the ductility is lowered and it acts as a factor in the occurrence of center segregation, which may cause disconnection during the drawing operation in the welding electrode manufacturing process. If the Mn content is too small, sufficient strength may not be secured, and it may become a cause of red hot brittleness. Accordingly, the Mn content may be 0.01 to 3.0% by weight.

Al: 0.50 wt% or less (excluding 0 wt%)

Aluminum (Al) is an element having a deoxidizing action, and may coarsen oxides to reduce toughness. Therefore, it is preferable to limit the Al content to 0.50 wt% or less (excluding 0 wt%).

Mg: 0.1 to 1.0 wt%

Magnesium (Mg) is an element having a deoxidizing action. When the Mg content is less than 0.1% by weight, toughness may be reduced, and when it is more than 1.0% by weight, the strength is excessively increased, and low-temperature cracking may occur. Accordingly, the Mg content may be 0.1 to 1.0% by weight.

Ti: 0.01 to 5.0 wt%

Titanium (Ti) is an element contributing to the improvement of the toughness of the wire. If the Ti content is less than 0.01% by weight, toughness may be reduced, and if it is more than 5.0% by weight, welding defects may occur. Accordingly, the Ti content may be 0.01 to 5.0% by weight.

Zr: 0.02 to 1.0 wt%

Zirconium (Zr) is advantageous in terms of securing the low-temperature toughness of the weld zone through the formation of precipitates, and is an element that greatly contributes to the improvement of workability of the welding material. If Zr is less than 0.02% by weight, it may be difficult to obtain such an effect. On the other hand, when Zr exceeds 1.0% by weight, the amount of zirconium precipitates increases to deteriorate workability as well as to deteriorate operating characteristics according to an increase in working temperature. Accordingly, the Zr content may be 0.02 to 1.0% by weight.

Ni: 0.01 to 4.0 wt%

Nickel (Ni) is not only effective in improving ductility to improve drawing processability, but also forms a stable structure even at cryogenic temperatures and is a necessary element to improve low-temperature impact properties. If the Ni content is too small, it may be difficult to obtain such an effect, and it may be difficult to stably operate the flux composition. On the other hand, if the Ni content is excessive, the drawability may deteriorate due to an increase in strength, and surface defects may be caused. Accordingly, the Ni content may be 0.01 to 4.0% by weight.

Mo: 0.01 to 1.0% by weight

Cr: 0.01 to 18.0 wt%

The flux-cored wire according to an embodiment of the present invention is characterized in that, with respect to the total weight of the wire, S ≤ 200 ppm and P+S ≤ 400 ppm. If the content of sulfur (S) and phosphorus (P) is too large, the solidification cracking susceptibility and stress relaxation cracking property can be significantly increased. Therefore, by minimizing the content of P and S, it is possible to minimize the low-temperature toughness and the occurrence of cracks in the weld zone.

In the flux-cored wire according to an embodiment of the present invention, with respect to the particle size of the final product of the flux filled inside the outer shell, the flux particle size (α): 5 μm or less Total ≤ 40 wt% (excluding 0 wt%), flux Particle size (β): 60㎛ or less Total ≤ 80% by weight, Flux particle size (γ: 1,000㎛ or less Total = 100% by weight. When the flux particle size is biased to a certain range, alloy elements are segregated in the flux Therefore, by controlling the flux particle size within the above-mentioned range to prevent segregation, welding workability can be improved.

The flux-cored wire according to an embodiment of the present invention is characterized in that the total moisture content of the wire is 500 ppm (excluding 0%) or less based on the total weight of the wire. When the total moisture content of the wire is too large, the diffusible hydrogen content increases and there is a risk of low-temperature cracking. Accordingly, it is possible to control the total moisture content of the wire within the above-described range to secure the low-temperature impact toughness of the welded portion and improve the workability of the welding material.

실시예Example

It consists of the alloy components and the remainder Fe, oxides, and unavoidable impurities summarized in Table 1 below, has the filling flux particle size in the final product summarized in Table 2, and contains the total moisture content of the final product summarized in Table 3 Examples (1) to (10) of the flux cored wire were prepared.

Quality uniformity (a) is measured by measuring the standard deviation of alloy components (Si, Mn, Cr, Ni, Mo) by analyzing the chemical composition of the pure deposited metal 5 times for each specimen according to the AWS welding standards, and if the value is less than 0.03 "Good", greater than 0.03 and less than 0.1 were indicated as "normal", and greater than 0.1 as poor.

Fault tolerance (b) is based on the welding conditions in Table 4, with the mechanical properties of AWS A5.20, A5.28, or A5.29, and the evaluation method (1) and the table Observe the evaluation method (2) for the presence or absence of wormholes on the surface of the weld when welding is performed under the welding conditions specified in 5. If (1) and (2) are both good, (○) and (2) are In (1), when 1 or 2 porosity occurs inside the weld, (Δ), and in (1) and (2), when a welding defect occurs, was evaluated as (×).

Crack resistance (c) was evaluated by pre-assembled steel materials in the shape shown in FIG. 1, welding under the conditions of Table 6, cooled to room temperature, and welding defects by PT (non-destructive liquid penetration test) welding test. If cracks did not occur for the entire length of the welding field, it was evaluated as “○”, if cracks occurred within 10%, “Δ”, and if more than 10%, “×” was evaluated. However, Example (6) is a heat-resistant material, Example (9) is for welding stainless steel thin plates for automobiles, and Example (10) is for surface hardening growth.

Table 7 shows the results of measuring the mechanical properties of the welded part of Examples (1) to (10) and the quality uniformity (a), defect resistance (b), and crack resistance (c) according to Tables 4 to 6 .

As can be seen in Table 7, Examples (1) to Example (10) have a yield strength (YS: Yeild Strength) of 405 MPa or more, and a tensile strength (TS: Tensile Strength) of 510 MPa or more, and elongation (EL: Elongation) is 22% or more, and it can be seen that all of them are excellent. In addition, in Examples (2) to (5), Examples (7) and (8), it can be confirmed that the impact energy at -40 ° C. is 68J or more, ensuring excellent low-temperature impact toughness.

In addition, as can be seen from Table 7, in Examples (1) to (10), the standard deviation of the alloy components (Si, Mn, Cr, Ni, Mo) was all measured to be 0.03 or less, so that the quality uniformity (a ) were all good.

And, in Examples (1) to (10), there was no occurrence of internal defects and no occurrence of wormholes on the surface of the welded portion, so the defect resistance (b) was also good.

In addition, in Examples (1) and (2), cracks occurred within 10% of the total length of the welding field during the non-destructive liquid penetration test, but Examples (3) to (5), and Example (7) and Example (8) showed good crack resistance because cracks did not occur over the entire length of the welding field. However, Example (6) is a heat-resistant material, Example (9) is for welding stainless steel thin plates for automobiles, and Example (10) is for surface hardening growth.

As such, the flux-cored wire according to the present invention uses a steel sheath containing alloy components, and by controlling the component composition of the sheath and flux, segregation is prevented, low-temperature toughness is stabilized, quality uniformity, defect resistance and resistance to defects Crackability can be improved.

The description of the present invention described above is for illustration, and those of ordinary skill in the art to which the present invention pertains can understand that it can be easily modified into other specific forms without changing the technical spirit or essential features of the present invention. will be. Therefore, it should be understood that the embodiments described above are illustrative in all respects and not restrictive. For example, each component described as a single type may be implemented in a dispersed form, and likewise components described as distributed may be implemented in a combined form.

The scope of the present invention is indicated by the following claims, and all changes or modifications derived from the meaning and scope of the claims and their equivalents should be construed as being included in the scope of the present invention.

Claims

A flux-cored wire filled with flux inside an alloy-type steel sheath, comprising:

The outer shell is based on the total weight of the wire, C: 0.001 to 0.06% by weight, P+S: 0.02% by weight or less (excluding 0% by weight), Si: 0.01 to 0.80% by weight, Mn: 0.01 to 3.0% by weight, Ni : 0.01 to 3.5% by weight, Cr: 0.01 to 18.0% by weight, Mo: 0.01 to 1.0% by weight, the balance contains Fe, oxides and unavoidable impurities,

The flux is based on the total weight of the wire, C: 0.08% by weight or less (excluding 0% by weight), Si: 0.01 to 1.5% by weight, Mn: 0.01 to 3.0% by weight, Al: 0.50% by weight or less (excluding 0% by weight) ), Mg: 0.1 to 1.0 wt%, Ti: 0.01 to 5.0 wt%, Zr: 0.02 to 1.0 wt%, Ni: 0.01 to 4.0 wt%, Mo: 0.01 to 1.0 wt%, Cr: 0.01 to 18 wt%, A flux cored wire comprising as balance Fe, oxides and unavoidable impurities.
According to claim 1,

For the total weight of the wire to minimize the occurrence of cracks in the weld zone,

While satisfying S ≤ 200 ppm, flux-cored wire, characterized in that P+S ≤ 400 ppm.
According to claim 1,

Regarding the particle size of the final product of the flux filled inside the shell,

Flux particle size (α): 5 μm or less in total ≤ 40 wt% (excluding 0 wt%), flux particle size (β): 60 μm or less in total ≤ 80 wt%, flux particle size (γ: 1,000 μm or less in total = 100 wt% Characterized in that, flux-cored wire.
According to claim 1,

A flux-cored wire, characterized in that the total moisture content of the wire is 500ppm (excluding 0% by weight) or less based on the total weight of the wire in order to prevent welding defects and reduce the amount of diffusible hydrogen.