KR20180083694A - Welding metal for dissimilar base material joint and welding method using the same - Google Patents

Abstract

Disclosed are a welding metal to joint heterogenous base materials, which minimizes generation of a coarse carbide causing a crack to improve welding quality of a welding portion of the heterogenous base materials, and a welding method using the same. According to the present invention, the welding metal to joint heterogenous base materials is used for joining a first base material and a second base material having a substance different from the first base material. The welding material comprises: 0.001 to 0.035 weight percent of C; 0.1 to 0.3 weight percent of Si; 0.1 to 2.0 weight percent of Mn; 25 to 35 weight percent of Cr; 50 to 65 weight percent of Ni; 0.1 to 1.0 weight percent of Al; 6 to 9 weight percent of Fe; and unavoidable impurities.

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a weld metal for welding different kinds of base materials,

The present invention relates to a welding metal for welding different kinds of base materials and a welding method using the same, and more particularly, to a welding method and a welding method using the same, which can improve the quality of welding to a welding part of a different base metal by minimizing the generation of coarse carbides To a welding metal for bonding a base material and a welding method using the same.

Dissimilar metal welding is widely used in power generation, chemical, petrochemical, and nuclear industries. This kind of dissimilar metal welding has been applied to high-tech and high-functional high-tech industrial fields such as aircraft, space industry, electronic equipment and low-temperature equipment due to technological and economical reasons.

At this time, the melting temperature and the solidification temperature of the dissimilar metal welding are different according to the difference of the metal chemical composition. If the melting temperature and the solidification temperature depend on the difference in the metal chemical composition, coarsening of the metal structure may occur during welding. Dissimilar metal welding has different lattice structure and physical properties depending on the difference of metal chemical composition, so there is a problem that cracking occurs frequently during solidification after welding and pores are easily generated.

For example, EU process furnace tubes use KHR 45A steel, a heat resistant steel of Kubota, and partially for sandwich tubes where coking is severe. APMT steel is used as an alternative.

At this time, the APMT steel was coated with Al ₂ O ₃ It forms an oxide layer and is resistant to carburization and coke formation at high temperature compared to conventional Cr-Ni alloy. When the APMT steel is used as a furnace tube, the decoking cycle can be extended from about 90 days to about 200 days, and the lifetime can be prolonged due to excellent submergence elasticity, thereby increasing the production efficiency and decreasing the cost of decoking. It has an economic effect.

FIG. 1 is an enlarged photograph of a joint portion of the dissimilar base material of FIG. 1, FIG. 3 is a cross-sectional view of a microstructure of the joint portion of the dissimilar base material of FIG. 1, And the percentages of the phases.

As shown in FIGS. 1 to 3, it was confirmed that many cracks were generated in the welded portion because the KHR 45A steel tube and the APMT steel tube were made of different materials during the operation of the plant.

That is, as shown in Figs. 1 and 2. It was confirmed that cracks occurred in many welds during operation at the weld interface between KHR 45A and APMT steels.

As a result of the detailed analysis of the cause of cracks, it was confirmed that excessive carbide (Cr ₂₃ C ₆ ) and intermetallic compound (NiAl) were excessively generated at the weld interface as shown in FIG. 3, It proceeded along the fragile Cr carbide.

This is because the carbon diffusing from the KHR 45A steel during operation is exposed to the APMT with little carbon solubility and is not able to diffuse and form coarse carbides. It is considered that Ni and Al are abundant locally due to the coarse carbide produced in this process, and a large amount of NiAl phase is generated.

A related prior art is Korean Patent Laid-Open Publication No. 10-2012-0075195 (published on Jul. 6, 2012), which discloses a ferritic stainless steel pipe and a manufacturing method thereof.

It is an object of the present invention to provide a weld metal for bonding a different type of base material and a welding method using the same, which can improve the quality of welding to a welded portion of a dissimilar base material by minimizing the generation of coarse carbides.

In order to accomplish the above object, a welding metal for welding a dissimilar base material according to a first embodiment of the present invention includes a first base metal and a welding metal for welding a different base metal used for welding the first base metal and the second base metal, Wherein the steel contains 0.001 to 0.035% of C, 0.1 to 0.3% of Si, 0.1 to 2.0% of Mn, 25 to 35% of Cr, 50 to 65% of Ni, 0.1 to 1.0% of Al, 6 to 9% and other unavoidable impurities.

According to a second aspect of the present invention, there is provided a welding metal for welding a dissimilar base material, the welding metal for use in welding a first base material and a second base material having a different material from the first base material, The steel sheet according to any one of claims 1 to 4, wherein the steel sheet contains 0.07 to 0.16% of C, 1.2% or less of Si, 1.5% or less of Mn, 19 to 22% of Cr, 31 to 35% of Ni, 39 to 49% of Fe, 0.6 to 1.6% And a control unit.

According to a first aspect of the present invention, there is provided a welding method using a welding metal for welding a dissimilar base material, comprising the steps of: (a) preparing a first base metal and a second base metal having a different material from the first base metal; And (b) subjecting the first and second base metals to different welding using a welding metal for bonding different parent materials, wherein the welding metal contains 0.001 to 0.035% of C, 0.1 to 0.1% of Si, To about 0.3%, Mn: about 0.1 to about 2.0%, Cr: about 25 to about 35%, Ni to about 50 to about 65%, Al to about 0.1 to about 1.0%, Fe to about 6 to about 9%, and other unavoidable impurities.

According to a second aspect of the present invention, there is provided a welding method using a welding metal for bonding a different type of base material, comprising the steps of: (a) preparing a first base material and a second base material having a different material from the first base material; And (b) subjecting the first and second base metals to different welding using a welding metal for bonding different base materials, wherein the welding metal contains 0.07 to 0.16% of C, 1.2 to 1.2% of Si, % Of Mn, 1.5% or less of Mn, 19 to 22% of Cr, 31 to 35% of Ni, 39 to 49% of Fe, and 0.6 to 1.6% of Nb.

In order to increase the carbon solubility, the welding metal for joining dissimilar base materials according to the present invention is characterized in that the amount of carbon is controlled to a very small amount, By welding between the base material and the second base material, excellent mechanical properties at high temperature can be ensured without the presence of carbide (Cr ₂₃ C ₆ ) at the interface between the first and second base materials.

As a result, the weld metal for welding different kinds of base materials according to the present invention and the welding method using the same can minimize the generation of coarse carbide, which is a cause of cracks, thereby improving the welding quality for the welded portion of the different base metal.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a photograph showing a structure in which a different type of base material is bonded. FIG.
FIG. 2 is an enlarged photograph of a joint portion of the dissimilar base material of FIG. 1; FIG.
FIG. 3 is a photograph showing the result of measurement of microstructure and phase fraction of the bonded portion of the dissimilar base material of FIG. 1;
4 is a view for explaining an application structure of a welding metal for bonding different kinds of base materials according to a first embodiment of the present invention.
5 is a view showing a state in which a dissimilar base material is bonded using a welding metal for bonding a different base material according to a second embodiment of the present invention.
6 is a photograph showing a result of a bead-on-plate test for a specimen according to Example 1. Fig.
7 is a photograph showing a result of a bead-on-plate test for a specimen according to Comparative Example 1. Fig.
8 is a photograph showing a result of a bead-on-plate test for a specimen according to Comparative Example 2. Fig.
9 is a photograph showing a result of performing a welding test on Example 1 and Comparative Example 2 which passed the bead-on-plate test result.
Fig. 10 is a photograph showing cut surfaces taken after the welding test for Examples 1 and 2 and Comparative Example 3; Fig.
11 is a photograph showing the results of high temperature tensile test for Examples 1 and 2 and Comparative Example 3;
Fig. 12 is a photograph showing the welding interface portion of the first embodiment immediately after welding and after heat treatment at 950 캜 for one week; Fig.
Fig. 13 is a photograph showing the welding interface portion after heat treatment at 950 占 폚 for one week for Examples 1 and 2 and Comparative Example 3; Fig.

BRIEF DESCRIPTION OF THE DRAWINGS The advantages and features of the present invention, and how to accomplish them, will become apparent by reference to the embodiments described in detail below with reference to the accompanying drawings. It should be understood, however, that the invention is not limited to the disclosed embodiments, but may be embodied in many different forms and should not be construed as being limited to the embodiments set forth herein. Rather, these embodiments are provided so that this disclosure will be thorough and complete, and will fully convey the scope of the invention to those skilled in the art. Is provided to fully convey the scope of the invention to those skilled in the art, and the invention is only defined by the scope of the claims. Like reference numerals refer to like elements throughout the specification.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, a welding metal for welding different kinds of base materials according to preferred embodiments of the present invention and a welding method using the same will be described in detail with reference to the accompanying drawings.

(Embodiment 1)

4 is a view for explaining an application structure of a welding metal for bonding different kinds of base materials according to the first embodiment of the present invention.

4, the welding metal 100 for bonding a different kind of base material according to the first embodiment of the present invention includes a first base material 120 and a second base material 140 having a different material from the first base material 120 ). ≪ / RTI >

Here, the first base material 120 may be a KHR 45A steel which is an heat resistant steel of Kubota Corporation for use as a tube for an EU process furnace, and the second base material 140 may be a coking May be Sandvik's APMT steel, which is used for partially replacing the tube of the present invention.

At this time, Sandvik's APMT steel was Fe-Cr-Al-Mo alloy as a ferrite material and Mo was further added to APM (Fe-Cr-Al) alloy to obtain an alloy having excellent creep resistance, strength, And is made of an alloy material which can be used up to a high temperature of about 1250 ° C.

Specifically, the first base material 120 contains 30 to 35% of Cr, 2.0% or less of Si, 2.0% or less of Mn, 0.5 to 1.8% of Nb, 0.4 to 0.6% of C, And other unavoidable impurities. The second base material 140 is composed of 18 to 25% of Cr, 1.0 to 8.0% of Al, 0.5 to 5.0% of Mo, 0.1 to 1.0% of Si, 0.1 to 1.5% of Mn, C: 0.01 to 0.10% and the balance Fe and other unavoidable impurities.

At this time, the second base material 140 of APMT steel has low carbon solubility. Therefore, when the first and second base materials 120 and 140 are welded and used as a tube for an EU process furnace, carbon is diffused in the first base material 120 of KHR 45A steel through operation at a high temperature for a long time. (Cr ₂₃ C ₆ ) is formed at the interface of the welded portion. During the production of such carbides, NiAl phase is generated in a large amount by the removal of nickel and aluminum. As a result, it is understood that cracks due to cracks are generated at the welding joint portion of the dissimilar base material.

In order to solve this problem, the inventors of the present invention have conducted many years of research. As a result, it has been found that, in order to successfully weld the first and second base materials 120 and 140 of different materials, It has been found that the formation of carbides should be minimized and it is necessary to increase the carbon solubility. For this purpose, it was found that the content of carbon (C) should be controlled to a very small amount while the content of nickel (Ni) should be increased and that the content of Cr should be strictly controlled to 25 to 35 wt% in order to secure high temperature properties.

That is, the weld metal 100 for bonding different kinds of base materials according to the first embodiment of the present invention contains 0.001 to 0.035% of C, 0.1 to 0.3% of Si, 0.1 to 2.0% of Mn, 35%, Ni: 50 to 65%, Al: 0.1 to 1.0%, Fe: 6 to 9%, and other unavoidable impurities.

The weld metal 100 further includes at least one selected from the group consisting of 0.06% or less of Ti, 0.04% or less of P, 0.006% or less of S, 0.1% or less of Nb, and 0.1% or less of Ta .

Here, carbon (C) is added for securing strength. However, in the present invention, it has been found out that it is desirable to control the content of carbon (C) to a very small amount so as to increase carbon solubility in order to minimize the generation of crude Cr-based carbide which is a cause of weld cracking. For this purpose, the carbon (C) is preferably added in a content ratio of 0.001 to 0.035% by weight of the total weight of the weld metal.

Silicon (Si) plays a role in strengthening the passivation film by the formation of SiO ₂ , in addition to the role of solid solution strengthening for bonding between solid solution metals. Silicon (Si) is preferably added in a content ratio of 0.1 to 0.3 wt% of the total weight of the weld metal. When the addition amount of silicon (Si) is less than 0.1% by weight, it is difficult to exhibit the above effect properly. On the contrary, when the addition amount of silicon (Si) exceeds 0.3% by weight, the welding solidification cracking susceptibility is remarkably increased.

Manganese (Mn) serves as a solid solution strengthener for bonding between metals. It is preferable that manganese (Mn) is added at a content ratio of 0.1 to 2.0 wt% of the total weight of the weld metal. When the addition amount of manganese (Mn) is less than 0.1% by weight, it may be difficult to secure strength and toughness as well as to secure the strength of the weld metal after welding due to lack of incombustibility and restriction of carbon which is detrimental to weldability. On the contrary, when the addition amount of manganese (Mn) is more than 2.0% by weight, the toughness is rapidly lowered and the cold workability is deteriorated.

Chromium (Cr) plays a role in improving oxidation resistance, high temperature corrosion resistance and high temperature strength. Therefore, it is preferable that chromium (Cr) is added at a content ratio of 25 to 35% of the total weight of the weld metal. When the addition amount of chromium (Cr) is less than 25% by weight, it is difficult to exhibit the above effect properly. On the contrary, when the amount of addition of chromium (Cr) is more than 35% by weight, chromium (Cr) and carbon (C) It is not desirable because of the great concern.

Nickel (Ni) serves to increase toughness and corrosion resistance. In addition, nickel (Ni) plays a role in increasing carbon solubility. Therefore, it is preferable that nickel (Ni) is added at a content ratio of 50 to 65% by weight of the total weight of the weld metal. When the addition amount of nickel (Ni) is less than 50% by weight, it is difficult to exert the above effect properly. On the contrary, when the addition amount of nickel (Ni) exceeds 65% by weight, there is a problem that the weld coagulation susceptibility of P is extremely high, which is not preferable.

Aluminum (Al) reacts with oxygen (O) entering from the outside air during welding and has a deoxidizing action. Therefore, aluminum (Al) is preferably added at a content ratio of 0.1 to 1.0 wt% of the total weight of the weld metal. When the addition amount of aluminum (Al) is less than 0.1% by weight, it is difficult to exert the above effect properly. On the contrary, when the amount of aluminum (Al) added exceeds 1.0 wt%, an excessive amount of intermetallic compound precipitates at a high temperature, resulting in a problem of significantly reducing toughness.

Phosphorus (P) is segregated at crystal grain boundaries and has a disadvantage of lowering toughness. Therefore, phosphorus (P) is preferably limited to 0.04 wt% or less of the total weight of the weld metal. In addition, sulfur (S) has a detrimental effect on cold workability by lowering toughness and forming emulsions. Therefore, sulfur (S) is preferably limited to 0.006% by weight or less of the total weight of the weld metal.

Hereinafter, a welding method using a welding metal for bonding different kinds of base materials according to a first embodiment of the present invention will be described.

The welding method using a welding metal for bonding different kinds of base materials according to the first embodiment of the present invention includes first and second base material preparing steps and a different welding step.

In the first and second base material preparation steps, a second base material having different materials from the first base material and the first base material is prepared.

The first base material is composed of 30 to 35% of Cr, 2.0% or less of Si, 2.0% or less of Mn, 0.5 to 1.8% of Nb, 0.4 to 0.6% of C and remaining Ni and other unavoidable impurities And the second base material is composed of 18 to 25% of Cr, 1.0 to 8.0% of Al, 0.5 to 5.0% of Mo, 0.1 to 1.0% of Si, 0.1 to 1.5% of Mn, C: 0.01 to 0.10% and the balance Fe and other unavoidable impurities.

In the different welding step, the first and second base metals are subjected to the different welding using the welding metal for bonding the different base materials.

In this case, the weld metal preferably contains 0.001 to 0.035% of C, 0.1 to 0.3% of Si, 0.1 to 2.0% of Mn, 25 to 35% of Cr, 50 to 65% of Ni, 0.1 to 1.0% of Al, And Fe: 6 to 9% and other unavoidable impurities.

The weld metal may further include at least one selected from the group consisting of Ti of 0.06% or less, P of 0.04% or less, S of 0.006% or less, Nb of 0.1% or less, and Ta of 0.1% or less.

Particularly, in the different welding step, it is preferable that the welding is carried out under the heat input condition of 1.0 to 2.5 kJ / cm 2, and the preferable heat input condition is 1.0 to 2.0 kJ / cm.

After the dissimilar welding step, it was confirmed that no carbide (Cr ₂₃ C ₆ ) was present at the interface between the first and second base metals. This is attributed to the use of a weld metal having an increased content of nickel while controlling carbon content to a very small amount in order to increase carbon solubility in welding between the first and second base metals of different materials .

(Second Embodiment)

5 is a view showing a state in which a dissimilar base material is bonded using a welding metal for bonding a different kind of base material according to a second embodiment of the present invention.

5, the weld metal 200 for bonding a different type of base material according to the second embodiment of the present invention includes a first base material 220 and a second base material 240 having a different material from the first base material 220 ). ≪ / RTI >

Here, the first base material 220 and the second base material 240 may be substantially the same as the first and second base materials (120 and 140 in FIG. 4) of the first embodiment, and redundant description will be omitted.

The weld metal 200 for welding a different type of base material according to the second embodiment of the present invention is composed of 0.07 to 0.16% of C, 1.2% or less of Si, 1.5% or less of Mn, 19 to 22% of Cr, 31 to 35% of Ni, 39 to 49% of Fe, and 0.6 to 1.6% of Nb.

In addition, the weld metal 200 for bonding different kinds of base materials according to the second embodiment of the present invention may further include at least one selected from 0.04% or less of P and 0.006% or less of S.

Carbon (C) is added for securing strength. However, in the present invention, it has been found out that it is desirable to control the carbon content to a very small amount so as to increase the carbon solubility in order to minimize the generation of crude Cr-based carbide which is a cause of weld cracking. For this, carbon (C) is preferably added in a content ratio of 0.07 to 0.16 wt% of the total weight of the weld metal.

Silicon (Si) plays a role in strengthening the passivation film by the formation of SiO2, in addition to the role of solid solution strengthening for bonding between solid solution metals. However, when the addition amount of silicon (Si) exceeds 1.2% by weight, the welding solidification cracking susceptibility is remarkably increased. Therefore, silicon (Si) is preferably added at a content ratio of 1.2% by weight or less based on the total weight of the weld metal.

Manganese (Mn) serves as a solid solution strengthener for bonding between metals. However, when the addition amount of manganese (Mn) is more than 1.5% by weight, the toughness is rapidly lowered, and the cold workability is deteriorated. Therefore, manganese (Mn) is preferably added at a content ratio of 1.5 wt% or less of the total weight of the weld metal.

Chromium (Cr) plays a role in improving oxidation resistance, high temperature corrosion resistance and high temperature strength. Therefore, it is preferable that chromium (Cr) is added at a content ratio of 19 to 22% of the total weight of the weld metal. When the addition amount of chromium (Cr) is less than 19% by weight, it is difficult to exhibit the above effect properly. On the other hand, when the addition amount of chromium (Cr) exceeds 22% by weight, although the addition amount of carbon (C) is controlled very little, there is a high possibility that Cr-based carbide is generated during chromium and carbon sensitization reaction at welding Which is undesirable.

Nickel (Ni) serves to increase toughness and corrosion resistance. In addition, nickel (Ni) plays a role in increasing carbon solubility. Therefore, it is preferable that nickel (Ni) is added at a content ratio of 31 to 35% by weight of the total weight of the weld metal. When the addition amount of nickel (Ni) is less than 31% by weight, it is difficult to exhibit the above effect properly. On the contrary, when the addition amount of nickel (Ni) exceeds 35% by weight, there is a problem that the weld coagulation susceptibility of P is extremely high, which is not preferable.

Niobium (Nb) is an effective element for improving the high-temperature strength including creep strength. Therefore, niobium (Nb) is preferably added in a content ratio of 0.6 to 1.6% by weight of the total weight of the weld metal. When the addition amount of niobium (Nb) is less than 0.6% by weight, it is difficult to exhibit the above-mentioned effect properly. On the other hand, when the amount of the niobium (Nb) added exceeds 1.6% by weight, the mechanical properties including toughness are greatly deteriorated.

Phosphorus (P) is segregated at crystal grain boundaries and has a disadvantage of lowering toughness. Therefore, phosphorus (P) is preferably limited to 0.04 wt% or less of the total weight of the weld metal. In addition, sulfur (S) has a detrimental effect on cold workability by lowering toughness and forming emulsions. Therefore, sulfur (S) is preferably limited to 0.006% by weight or less of the total weight of the weld metal.

Hereinafter, a welding method using a welding metal for bonding different kinds of base materials according to a second embodiment of the present invention will be described.

A welding method using a welding metal for bonding different kinds of base materials according to a second embodiment of the present invention includes first and second base material preparing steps and a different welding step.

In the first and second base material preparation steps, a second base material having different materials from the first base material and the first base material is prepared.

The first base material is composed of 30 to 35% of Cr, 2.0% or less of Si, 2.0% or less of Mn, 0.5 to 1.8% of Nb, 0.4 to 0.6% of C and remaining Ni and other unavoidable impurities And the second base material is composed of 18 to 25% of Cr, 1.0 to 8.0% of Al, 0.5 to 5.0% of Mo, 0.1 to 1.0% of Si, 0.1 to 1.5% of Mn, C: 0.01 to 0.10% and the balance Fe and other unavoidable impurities.

In the different welding step, the first and second base metals are subjected to the different welding using the welding metal for bonding the different base materials.

In this case, the weld metal preferably contains 0.07 to 0.16% of C, 1.2% or less of Si, 1.5% or less of Mn, 19 to 22% of Cr, 31 to 35% of Ni, 39 to 49% of Fe, : 0.6 to 1.6%.

Further, the weld metal may further include at least one selected from 0.04% or less of P and 0.006% or less of S.

Particularly, in the different welding step, it is preferable that the welding is carried out under the heat input condition of 1.0 to 2.5 kJ / cm 2, and the preferable heat input condition is 1.0 to 2.0 kJ / cm.

After the dissimilar welding step, it was confirmed that no carbide (Cr ₂₃ C ₆ ) was present at the interface between the first and second base metals. This is attributed to the use of a weld metal having an increased content of nickel while controlling carbon content to a very small amount in order to increase carbon solubility in welding between the first and second base metals of different materials .

As described above, according to the embodiments of the present invention, in order to increase the carbon solubility, the amount of carbon is controlled to be very small and the content of nickel is increased By welding the first base material and the second base material of different materials using the welding metal, excellent mechanical properties at high temperatures can be ensured without the presence of carbide (Cr ₂₃ C ₆ ) at the interface between the first and second base materials .

As a result, according to the embodiments of the present invention, the welding metal for welding different kinds of base materials and the welding method using the same can minimize the generation of coarse carbides, which is a cause of cracks, It is effective.

Example

Hereinafter, the configuration and operation of the present invention will be described in more detail with reference to preferred embodiments of the present invention. It is to be understood, however, that the same is by way of illustration and example only and is not to be construed in a limiting sense.

The contents not described here are sufficiently technically inferior to those skilled in the art, and a description thereof will be omitted.

1. Experimental Method

Table 1 shows the composition for the first and second base metals, and Table 2 shows the composition for the weld metal according to Examples 1 and 2 and Comparative Examples 1 to 3. [ Here, in order to confirm the weldability between APMT and Example 1 and Comparative Examples 1 and 2, a bead on plate test was performed by changing the heat input according to the test conditions shown in Table 3.

[Table 1] (unit:% by weight)

[Table 2] (unit:% by weight)

[Table 3]

2. Microstructure Observation

FIG. 6 is a photograph showing the result of the bead-on-plate test for the specimen according to Example 1, FIG. 7 is a photograph showing the result of the bead-on-plate test for the specimen according to Comparative Example 1, FIG. 6 is a photograph showing a result of a bead-on-plate test for a specimen. FIG.

As shown in FIG. 6, as a result of the bead-on-plate test, the cracks did not occur under the conditions of 1.5 kJ and 2.0 KJ in the case of Example 1, but cracks occurred under the condition of the heat input of 3.5 kJ.

On the other hand, as shown in FIG. 7, as a result of the bead-on-plate test, in the case of Comparative Example 1, cracks occurred in both of the heat input amounts of 1.5 kJ, 2 kJ and 3.5 kJ.

As shown in Fig. 8, as a result of the bead-on-plate test, in the case of Comparative Example 2, cracks did not occur in all of the heat input amounts of 1.5 kJ, 2 kJ and 3.5 kJ.

3. Property evaluation

Table 4 shows the results of measurement of mechanical properties for Example 1 and Comparative Example 2, and FIG. 9 is a photograph showing the results of the welding tests for Example 1 and Comparative Example 2 that passed the bead-on-plate test result.

[Table 4]

As shown in Table 4 and FIG. 9, welding tests were conducted for Example 1 and Comparative Example 2 that passed the bead-on-plate test results. As a result, it was confirmed that all welds were excellent, (1000 ° C) were also confirmed to satisfy the specifications.

On the other hand, FIG. 10 is a photograph showing the cutting surfaces after the welding test for Examples 1 and 2 and Comparative Example 3. In this case, in FIGS. 10A and 10B, the first and second examples and the third comparative example are the welding test results with the heat input of 1.5 kJ and 2 kJ.

As shown in Fig. 10, the weldability of the cut surface immediately after the welding test was confirmed, and it was confirmed that Examples 1 and 2 and Comparative Example 3 all exhibited excellent weldability without defects.

Table 5 shows the tensile test results for Examples 1 and 2 and Comparative Example 3, and FIG. 11 is a photograph showing the results of the high temperature tensile test for Examples 1 and 2 and Comparative Example 3. In order to confirm the weldability of Examples 1 and 2 and Comparative Example 3, specimens were prepared for both cases immediately after welding and exposed for one week at 950 ° C. , and subjected to room temperature and high temperature tensile tests.

[Table 5]

As shown in Table 5 and FIG. 11, at room temperature tensile test results, it was confirmed that all specimens were broken at the base material.

However, in the high temperature tensile test, most of the specimens were fractured at the weld interface, but they exhibited properties exceeding the base metal strength

Particularly, in the case of the test piece according to Example 1, after the test piece was exposed at 950 ° C for 1 week, it was broken at the base material portion rather than at the weld interface, and the recovery of the high temperature elongation was confirmed to be 41.4%. Respectively.

On the other hand, FIG. 12 is a photograph showing the welding interface portion of the first embodiment immediately after welding and after heat treatment at 950 ° C. for one week.

As shown in FIG. 12, a SEM photograph of the weld interface immediately after welding was observed. As a result, a mixed zone was observed for the specimen according to Example 1, and after heat treatment at 950 ° C. for one week, And the area expanded to 57 mu m.

At this time, in the case of the specimen according to Example 1, a part of the NiAl phase was generated in the mixed region of the weld interface, but no Cr-based carbide was observed.

FIG. 13 is a photograph showing the welding interface portion after heat treatment at 950.degree. C. for one week for Examples 1 and 2 and Comparative Example 3; FIG.

13, in the case of the specimens according to Example 2 and Comparative Example 3, after the heat treatment at 950 ° C for one week, the mixed zone of the weld interface was observed, Only the NiAl phase was observed.

Particularly, in the case of the specimen according to Example 2, only precipitation of Nb carbide was confirmed, and no Cr carbide was found.

Although the preferred embodiments of the present invention have been disclosed for illustrative purposes, those skilled in the art will appreciate that various modifications, additions and substitutions are possible, without departing from the scope and spirit of the invention as disclosed in the accompanying claims. These changes and modifications may be made without departing from the scope of the present invention. Accordingly, the scope of the present invention should be determined by the following claims.

100: Weld metal for bonding different base materials
120: First base material
140: Second base material

Claims (20)

A welding metal for bonding a different base material used for welding a first base metal and a second base metal having different materials to the first base metal,
The steel sheet according to any one of claims 1 to 3, wherein the steel contains 0.001 to 0.035% of C, 0.1 to 0.3% of Si, 0.1 to 2.0% of Mn, 25 to 35% of Cr, 50 to 65% of Ni, 0.1 to 1.0% 9% and other unavoidable impurities.
The method according to claim 1,
The weld metal
And further comprising at least one selected from the group consisting of Ti: not more than 0.06%, P: not more than 0.04%, S: not more than 0.006%, Nb: not more than 0.1%, and Ta: not more than 0.1% Weld metal.
The method according to claim 1,
The first preform
, Characterized in that it is composed of 30 to 35% of Cr, 2.0% or less of Si, 2.0% or less of Mn, 0.5 to 1.8% of Nb, 0.4 to 0.6% of C and remaining Ni and other unavoidable impurities Weld metal for joining dissimilar materials.
The method according to claim 1,
The second preform
The steel sheet according to any one of claims 1 to 3, wherein the steel sheet contains, by weight%, 18 to 25% of Cr, 1.0 to 8.0% of Al, 0.5 to 5.0% of Mo, 0.1 to 1.0% of Si, 0.1 to 1.5% of Mn, 0.01 to 0.10% Wherein the molten metal is composed of unavoidable impurities.
A welding metal for a two-iron base material used for welding a first base metal and a second base metal having a different material from the first base metal,
The steel sheet according to any one of claims 1 to 4, wherein the steel sheet contains 0.07 to 0.16% of C, 1.2% or less of Si, 1.5% or less of Mn, 19 to 22% of Cr, 31 to 35% of Ni, 39 to 49% of Fe, 0.6 to 1.6% The weld metal for bonding the different base materials.
6. The method of claim 5,
The weld metal
P: 0.04% or less, and S: 0.006% or less.
6. The method of claim 5,
The first preform
, Characterized in that it is composed of 30 to 35% of Cr, 2.0% or less of Si, 2.0% or less of Mn, 0.5 to 1.8% of Nb, 0.4 to 0.6% of C and remaining Ni and other unavoidable impurities Weld metal for joining dissimilar materials.
6. The method of claim 5,
The second preform
The steel sheet according to any one of claims 1 to 3, wherein the steel sheet contains, by weight%, 18 to 25% of Cr, 1.0 to 8.0% of Al, 0.5 to 5.0% of Mo, 0.1 to 1.0% of Si, 0.1 to 1.5% of Mn, 0.01 to 0.10% Wherein the molten metal is composed of unavoidable impurities.
(a) preparing a first parent material and a second parent material having a different material from the first parent material; And
(b) performing different welding using the welding metal for bonding the first and second base metals to each other,
Wherein the weld metal contains 0.001 to 0.035% of C, 0.1 to 0.3% of Si, 0.1 to 2.0% of Mn, 25 to 35% of Cr, 50 to 65% of Ni, 0.1 to 1.0% of Al, Fe: Welding method using welding metal for bonding different materials, containing 6 to 9% and other unavoidable impurities.
10. The method of claim 9,
The weld metal
And further comprising at least one selected from the group consisting of Ti: not more than 0.06%, P: not more than 0.04%, S: not more than 0.006%, Nb: not more than 0.1%, and Ta: not more than 0.1% Welding method using welding metal.
10. The method of claim 9,
The first preform
, Characterized in that it is composed of 30 to 35% of Cr, 2.0% or less of Si, 2.0% or less of Mn, 0.5 to 1.8% of Nb, 0.4 to 0.6% of C and remaining Ni and other unavoidable impurities Welding method using welding metal for bonding different base materials.
10. The method of claim 9,
The second preform
The steel sheet according to any one of claims 1 to 3, wherein the steel sheet contains, by weight%, 18 to 25% of Cr, 1.0 to 8.0% of Al, 0.5 to 5.0% of Mo, 0.1 to 1.0% of Si, 0.1 to 1.5% of Mn, 0.01 to 0.10% Wherein the weld metal is formed of unavoidable impurities.
10. The method of claim 9,
In the step (b)
The welding
Wherein the heat treatment is carried out under an input heat amount of 1.0 to 2.5 kJ / cm.
10. The method of claim 9,
After the step (b)
At the interface between the first and second base metals,
Wherein no carbide (Cr ₂₃ C ₆ ) is present.
(a) preparing a first parent material and a second parent material having a different material from the first parent material; And
(b) performing different welding using the welding metal for bonding the first and second base metals to each other,
Wherein the weld metal contains 0.07 to 0.16% of C, 1.2% or less of Si, 1.5% or less of Mn, 19 to 22% of Cr, 31 to 35% of Ni, 39 to 49% of Fe, Welding method using welding metal for joining dissimilar materials including 0.6 to 1.6%.
16. The method of claim 15,
The weld metal
0.04% or less of P, and 0.006% or less of S, based on the total weight of the weld metal.
16. The method of claim 15,
The first preform
, Characterized in that it is composed of 30 to 35% of Cr, 2.0% or less of Si, 2.0% or less of Mn, 0.5 to 1.8% of Nb, 0.4 to 0.6% of C and remaining Ni and other unavoidable impurities Welding method using welding metal for bonding different base materials.
16. The method of claim 15,
The second preform
The steel sheet according to any one of claims 1 to 3, wherein the steel sheet contains, by weight%, 18 to 25% of Cr, 1.0 to 8.0% of Al, 0.5 to 5.0% of Mo, 0.1 to 1.0% of Si, 0.1 to 1.5% of Mn, 0.01 to 0.10% Wherein the weld metal is formed of unavoidable impurities.
16. The method of claim 15,
In the step (b)
The welding
Wherein the heat treatment is carried out under an input heat amount of 1.0 to 2.5 kJ / cm.
16. The method of claim 15,
After the step (b)
At the interface between the first and second base metals,
Wherein no carbide (Cr ₂₃ C ₆ ) is present.

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