JPH07185881A - Coated electrode for cr-mo-based rail - Google Patents

Abstract

PURPOSE:To provide a coated electrode with which joint performance excellent in terms of wear resistance and surface flaw resistance is assured and which has good welding workability at the time of subjecting a Cr-Mo-based rail steel to enclosed arc butt welding and repair build-up welding at an on-site track. CONSTITUTION:A coating material contains, by weight % of the total weight of the coating material, 25 to 45% carbonate, 15 to 30% metal fluoride, 3 to 9% rutile and the balance a coating material and arc stabilizer. A welding electrode is coated with this coating material at 20 to 30% of the total weight of the welding electrode. The coated electrode which contains, by weight % of the respective components occupied in the total metal of the welding electrode, 0.1 to 0.39% C, 0.35 to 0.9% Si, 0.75 to 2.0% Mn, 0.9 to 2.5% Cr, 0.1 to 0.6% Mo or contains at least one : kinds of 0.02 to 0.15% V, 0.02 to 0.1% Nb, 0.2 to 0.5% Cu and 0.5 to 3% Ni in addition to the above and consists of the balance Fe with inevitable impurities is obtd.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to medium C-Cr-Mo for railways.
TECHNICAL FIELD The present invention relates to a coated arc welding rod used in the enclosed arc welding and the repair welding of a system rail steel.

[0002]

2. Description of the Related Art FIG. 1 shows a cross section of a rail, 1 is a foot,
2 is the abdomen, 3 is the head, and 4 is the head surface. Conventionally, in the field butt welding of rails, the joint rail end face is set to the I groove, the rail foot is multi-layer welded, and then the abdomen 2 and the head 3 are surrounded by the enclosed metal material, and continuous bar splicing is performed. Enclosed arc welding method for arc welding is applied. Further, a method of repairing a locally damaged portion or a worn portion generated on the rail head surface 4 by multilayer overlay welding is also widely used.

For the purpose of its use, the rail is required to have high wear resistance against wheel bump contact and fatigue resistance against fatigue cracks on the head surface. On the other hand, the foot and abdomen are required to have static strength and fatigue strength that can withstand the impact and bending load when passing through the wheels. Further, it is necessary to minimize welding defects such as weld cracks.

At present, the metal structure of rail steel most widely used in the world has a C content of 0.5% in consideration of strength and wear resistance.
~ A high C pearlite structure that is close to the eutectoid composition and has a strength level of 700 MPa or more is selected. As part of the development of welding technology suitable for such high-strength, high-wear-resistant rail steel, the inventors of the present invention have come up with a common metal welding technology in which the composition of the deposited metal is similar to that of the base metal. As a result of advancing research and development, as is apparent from Japanese Patent Publication No. 4-54557, Japanese Patent Publication No. 4-55793, Japanese Patent Laid-Open Nos. 2-229693 and 2-258193,
It has been possible to develop a covered arc welding rod that solves the wear resistance and damage resistance or crack resistance of the welded portion, which has been a problem in the prior art, and that also has good welding workability. In addition, we have established an enclosed arc welding technology for high C pearlite rails using this newly developed welding rod, and have been able to achieve its practical application.

However, the above-mentioned high-C pearlite rail steel is likely to accumulate fatigue damage on the rail head surface depending on the operating environment such as a straight section of a high-speed line due to the recent increase in train speed, resulting in dark spots and flares. It is also true that the occurrence of surface damage such as kings is becoming a problem. As a way to prevent this surface damage from occurring, select a material system that maintains high strength (hardness) and slightly reduce wear resistance, and promote mild wear to eliminate early fatigue damage at the same time. There is a choice to prevent flaking by taking advantage of plastic deformation resistance (performance of suppressing metal flow) that has high strength characteristics. As one of the material candidates having such characteristics, a medium C—Cr—Mo rail steel exhibiting a bainite structure is drawing attention, and Japanese Patent Application No. 5-129729 and Japanese Patent Application No. 5-129729.
As shown in Japanese Patent No. 120265, development of bainite-based rail steel, which is considered to partially replace the conventional high-C pearlite-based rail steel in the future, is also in progress.

[0006]

The characteristics of the above-mentioned medium C-Cr-Mo system rail steel for high-speed railway, which is being newly developed, is that, as shown in Table 1, a typical example is bainite having a fine metal structure. , Vickers hardness of 390 or more, tensile strength of 1
Although it exhibits a pressure of 100 MPa or more, it is indispensable to accompany the joining technology in order to commercialize it as a practical material. That is, it is necessary to establish a proper covered arc welding rod and a proper welding technique using the same for the enclosed arc welding which is one of the existing on-site fusion welding methods.

[0007]

[Table 1]

Table 2 shows a list of the coated arc welding rods that have been used so far for the enclosed arc welding or repair welding of rails. First, as described above, a high-carbon co-metal alloy coated arc welding rod for high-C pearlite rail steel is a newly developed product that overcomes the wear resistance, damage resistance, and crack resistance that have been problems with existing welding rods. Although it is a welding rod,
When combined with medium C-Cr-Mo bainite rail steel, hardness and strength are also shown in Table 2 due to the difference in the original technical concept.
In addition to not being able to obtain the values shown in the figure, abnormal structures that are unfavorable in terms of joint performance occur at the fusion boundary, and the bainite rail cannot fulfill its intended function of preventing surface damage during use and bending. Satisfactory static strength and fatigue strength under load cannot be obtained.

[0009]

[Table 2]

Next, the coated arc welding rod for low alloy high strength steel, unlike the combination with high C pearlite rail steel, the combination with medium C-Cr-Mo bainite rail steel has a melting boundary. Since the problems of high temperature cracking (HAZ liquefaction cracking) and the occurrence of martensite structure in the vicinity can be solved, the ease of application is greatly improved. However, since the mechanical property values of the weld metal can be obtained only at the levels shown in Table 2, there is no problem when applied to the rail foot, abdomen and middle head, but when applied to the rail head surface part. However, bainite rails cannot play a role in preventing surface damage such as dark spots and flaking.

Further, the coated arc welding rod for hardfacing is classified into two groups, DF2A and DF2B. Since the welding rod classified as DF2A is similar to the above-mentioned welding rod for low-alloy high-strength steel, in principle, the above problem still applies. It should be noted that some of the materials have solved the above-mentioned problems regarding hardness and strength, but since the alloying elements are added excessively, the specific resistance value becomes excessive, and the signal in terms of electrical conduction characteristics is increased. There is a risk of defects, which is a problem from the viewpoint of applicability. On the other hand, DF
The weld metal formed by the welding rod classified as 2B has a high C martensite structure and has a high hardness in order to secure earth and sand wear resistance that allows the presence of minute cracks. However, it cannot be applied at all to the problem of metal wear resistance, which is essentially the object of not allowing cracking, from the viewpoint of excessive hardness, difference in structure and cracking.

Under these circumstances, it is an object of the present invention to provide a new coated arc welding rod for rails having a fine bainite structure which is excellent in strength, wear resistance and damage resistance without any electric conduction characteristics. .

[0013]

In order to achieve the above object, the gist of the present invention is that, with respect to the total weight of the coating agent,
Carbonate is 25-45% by weight, metal fluoride is 15-
30%, rutile 3-9%, the balance contains coating agent and arc stabilizer, and the coating agent is 20-3 with respect to the total weight of the welding rod.
0% coating, each component occupying the total metal in the welding rod is wt%
C: 0.1 to 0.39%, Si: 0.35 to 0.9
%, Mn: 0.75 to 2.0%, Cr: 0.9 to 2.5
%, Mo: 0.1 to 0.6%, and the balance being Fe and unavoidable impurities, which is a covered arc welding rod for a Cr-Mo-based rail. Further, the carbonate is 25 to 45% and the metal fluoride is 1% by weight based on the total weight of the coating agent.
5 to 30%, rutile 3 to 9%, the balance contains a coating agent and an arc stabilizer, and the coating agent is 20 relative to the total weight of the welding rod.
.About.30%, and each component occupying all the metals in the welding rod is C: 0.1 to 0.39% by weight, Si: 0.35 to 0.
9%, Mn: 0.75 to 2.0%, Cr: 0.9 to 2.
5%, Mo: 0.1-0.6%, V: 0.02-
0.15%, Nb: 0.02-0.1%, Cu: 0.2
˜0.5%, Ni: 0.5 to 3%, one or more kinds, and the balance consisting of Fe and unavoidable impurities. A coated arc welding rod for a Cr—Mo system rail. .

[0014]

The present invention will be described in detail below. First, the reason for defining the composition of the coating material will be described. Carbonates (carbonates here means one or more of lime carbonate, barium carbonate, magnesium carbonate) are decomposed by arc heat during welding to generate carbon dioxide gas and shut off the molten pool from the atmosphere. It is possible to prevent the occurrence of pits and blow holes. Further, it has a remarkable effect on the improvement of arc stability and slag removability, and also plays a role of adjusting the viscosity of slag, so that it is used as a main raw material for welding rods.
However, if the content of carbonate is less than 25%, the shielding ability by the generated gas formed at the tip of the welding rod becomes poor, and the arc becomes unstable, spatter increases and pits and blowholes occur during welding work in a wind environment. Is not preferred. On the other hand, if it exceeds 45%, excessive gas generation causes an increase in spatter, the amount of slag generated increases, and the slag viscosity increases, so that stable welding cannot be performed. In particular, the increase in slag amount and slag viscosity means that
In arc welding of rail steel containing a large amount of C,
It is unfavorable because it interferes with welding workability. Furthermore, in enclosed arc welding, which encloses the welded area with a metal and continuously welds it inside, the amount of slag is reduced to the extent that arc stability is not impaired, and the slag viscosity is suppressed to a low level immediately below the arc. It is important to remove the slag smoothly behind the weld. For these reasons, carbonate
It was defined as 5 to 45%.

The metal fluoride (the metal fluoride here means one or more of calcium fluoride, sodium fluoride and magnesium fluoride) is effective in adjusting the viscosity and fluidity of the slag. By appropriately adjusting the metal fluoride, the spread of the welding bead becomes large. However, if the metal fluoride content is less than 15%, the slag fluidity deteriorates and the slag becomes entangled at the arc tip of the welding rod, making stable welding impossible. On the other hand, if it exceeds 30%, the amount of slag becomes excessive and the fluidity of the slag becomes too large, and the slag flows unnecessarily in front of the welding and stable welding cannot be performed. For these reasons, the metal fluoride content is defined as 15 to 30%.

Rutile is effective in maintaining arc viscosity stability while maintaining good slag viscosity. However, if it is less than 3%, the effect is not sufficient, and there are many problems such as generation of spatter. Also,
If it exceeds 9%, the melting point of slag is high and the viscosity of slag is large, so that stable welding cannot be performed. Therefore, the rutile is defined as 3 to 9%.

Potassium feldspar and mica, iron powder and ferroalloy are used as arc stabilizers, and sodium silicate is used as a coating agent.
Magnesia oxide and an organic material are contained in the balance.

Next, the coating agent is added to the total weight of the molten rod by 20
The reason for applying ~ 30% will be described. The coverage is defined by the equation (1) shown below. Coverage _{= {F W / (F W} + R W)} × 100 (%) ............... (1) equation where F _W: coating weight, R _W: core weight

When the coverage calculated by the equation (1) is less than 20%, the arc protection cylinder formed at the tip of the welding rod is structurally weak, and there is a high risk that the coating will be missing during welding. Moreover, since the shield is likely to be incomplete, a large amount of spatter is generated, which is a problem. On the other hand, if it exceeds 30%, the amount of slag produced becomes excessively large, and the molten slag cannot be smoothly removed from the molten pool, so that stable welding cannot be performed. Therefore, the weight of the coating material relative to the total weight of the welding rod is 20 to 3
It was defined as 0%.

Next, the reason for defining the range of each alloy component in the total metal in the welding rod will be described. C is medium C-
It is an essential component for forming in the weld metal a bainite structure in which fine precipitates similar to those of Cr-Mo rail steel are dispersed and precipitated. As the C content of the deposited metal increases, the hardness and tensile strength and thus the plastic deformation resistance increase, so that the wear resistance and flaking resistance of the molten metal can be improved. When the C content of the total metal in the welding rod is less than 0.1%, the C of the weld metal of the obtained joint is
In some cases, the amount becomes less than 0.1%, and the absolute amount of precipitates formed in the other bainite structure becomes insufficient, resulting in insufficient strength and deterioration in wear resistance and flaking resistance. On the other hand, when the C content of the total metal in the welding rod exceeds 0.39%, the C content of the weld metal of the obtained joint is 0.35%.
It becomes super, and a brittle structure is formed in association with Cr and Mo essential addition elements. Further, in terms of electrical conductivity, too, the specific resistance value becomes excessively large, so that it cannot be used as a welded joint.
It was defined as ~ 0.39%.

Si is generally added to the welding rod as a deoxidizing agent for the weld metal, but the amount of Si in the weld metal must be controlled within the range of 0.3 to 0.75%. . If the Si content of the total metal in the welding rod is less than 0.35%, the Si content of the weld metal will be less than 0.3%, the deoxidizing effect during welding will be insufficient, and pits or blowholes will occur. . On the other hand, the Si content of all the metals in the welding rod is 0.
If it exceeds 9%, the amount of Si in the weld metal exceeds 0.75%,
Since the specific resistance value becomes too large in terms of electrical conductivity and it cannot be used as a welded joint, the Si content of the total metal in the welding rod is specified to be 0.35 to 0.9%.

Mn, like Si, acts as a deoxidizing agent for the deposited metal and, like the carbide forming element, delays the start of bainite transformation and shifts to a low temperature and long time side. As described above, in the case of low-temperature transformation generation, even if the heating-cooling history due to welding changes a little, the structure does not change so much, and there is an advantage that an extremely stable bainite structure with high strength is formed. In general, it is desirable that the Mn content of the weld metal substantially corresponds to that of the base rail steel. When the Mn content of all the metals in the welding rod is less than 0.75%, the Mn content in the weld metal decreases to less than 0.7% and the formation of the structure becomes unstable, so the strength and ductility of the weld metal deteriorate. As a result, wear resistance and flaking resistance become problems. On the other hand, when the Mn content of all the metals in the welding rod exceeds 2.0%, the Mn content in the weld metal exceeds 1.5%, and in addition to the components related to carbide precipitation (C, Cr, Mo) which are essential addition components. Etc., the hardenability becomes excessively large, which causes a problem because precipitation of an embrittlement structure and an excessive degree of hardening occur. In addition, the Mn content of the total metal in the welding rod is specified to be 0.75 to 2.0% from the viewpoint that it is difficult to control the specific resistance value to a certain value or less from the viewpoint of electric conduction characteristics. did.

Cr and Mo are both components that retard bainite transformation and carbide-forming elements, similar to Mn, and wear resistance and resistance are improved through fine dispersed precipitates formed in a stable bainite structure. It contributes to the securing of damage resistance and flaking resistance, and is an important and essential additive component in constituting the present invention. Regarding the Cr and Mo contents of the Cr-Mo system rail steel, Cr is about 1 to 2% and M, respectively.
O is added up to about 0.5%, but C of weld metal
It is desirable that the amounts of r and Mo substantially correspond to those of the rail base material. When the Cr content of all the metals in the welding rod is less than 0.9%,
The amount of Cr in the weld metal decreases to less than 0.8%, and as a result, the structure formation is largely dependent on the welding cooling rate and becomes unstable, which is a problem. Similarly, if the Mo content of the total metal in the welding rod is less than 0.1%, the Mo content in the weld metal is also 0.1%.
This is a problem because it is less than the above range and the structure cannot be stabilized, and in addition, necessary hardness, strength and plastic deformation resistance cannot be secured. On the other hand, Cr of all metals in the welding rod is 2.5
%, And Mo in excess of 0.6%, respectively, causes excessive hardening due to excessive precipitation of carbides, which becomes a problem. Further, from the viewpoint that it is not preferable in terms of electric conduction characteristics, the Cr content of the metal in the welding rod is specified to be 0.9 to 2.5%, and the Mo content is specified to be 0.1 to 0.6%.

The base material rail is the above-mentioned C, Si, M.
When one or more of V, Nb, Cu, and Ni are contained in addition to n, Cr, and Mo, the weld metal contains these alloy components in an amount equal to or less than that of the base metal rail. Need to let. It should be noted that these components are expected to have a yield of 100% with respect to the deposited metal, regardless of whether the alloy components are added to the core wire or the coating material in the welding rod.

That is, V, like Mn, Cr and Mo, is a component that delays bainite transformation and is a carbide-forming element, and the stability and strength characteristics of the structure also change depending on the content, so the base metal rail is V. When containing
If the coated arc welding rod applied to at least the rail head surface portion also does not contain V, the wear resistance, damage resistance and flaking resistance of the weld metal deteriorate. Therefore, the V content of the weld metal is 0.01% or more, preferably 0.0
It must be contained at 15% or more. However, when the V content of the weld metal exceeds 0.1%, the crack resistance deteriorates due to mutual interference with Cr and Mo which are other carbide precipitation elements, so the V content of the total metal in the welding rod is covered. Considering 0.0
It was defined as 2 to 0.15%.

Since Nb is a component that promotes transformation, it has an effect of preventing harmful martensite generated during cooling after welding. Therefore, the Nb content of the weld metal is 0.
It is necessary that the content be 01% or more, preferably 0.015% or more. However, the Nb content of the weld metal is 0.07%
If it exceeds 1.0, coarse carbon / nitride is generated, and toughness and fatigue strength are reduced. Therefore, the Nb content of the total metal in the welding rod is specified to be 0.02 to 0.1% or less in consideration of the coverage.

Cu is an effective component for improving the corrosion resistance of the rail steel and is contained in the rail steel in consideration of the corrosion resistance up to about 0.3%. Therefore, in the welding of this type of rail, if the weld metal does not contain 0.15 to 0.3% Cu, the corrosion resistance of the welded part is deteriorated and local corrosion deterioration is caused. However, the weld metal Cu
If the content exceeds 0.3%, hot brittleness occurs and defects occur. Therefore, the Cu content relative to the total metal in the welding rod is defined as 0.2 to 0.5% in consideration of the coverage.

Ni is a component that improves ductility or toughness, and may be rarely added to rail steel. The effect is the same for weld metal as well.
It is sufficient if the content is up to 2%. Moreover, N in the weld metal
If the i content exceeds 2%, the high temperature solidification cracking susceptibility increases, which is not preferable. Therefore, the Ni content of the total metal in the welding rod is defined as 0.5 to 3% in consideration of the coverage.

The unavoidable impurity components such as P, S, N and O must be 0.05% or less in total of P + S and 0.05% or less in total of O + N as the total metal content in the welding rod. Is desirable.

In the coated arc welding rod for medium C-Cr-Mo rail steel according to the present invention, the wire diameter of the welding core wire, the coating rate of the coating agent, the composition of the coating agent composition, etc. can be selected appropriately. Welded joints that can be welded without causing welding defects even when subjected to rail welding under generally prescribed standard welding conditions, and have strength, hardness and bainite structure almost equivalent to the base metal rail in the as-welded state. Can be formed. The effects of the present invention will be specifically described below with reference to examples.

[0031]

[Examples] The three types of wire rods shown in Table 3 were used as welding cores, and the coating compositions of the coated arc welding rods used in the test in combination with Cr-Mo bainite rails and each element contained in the total metal in the welding rods were used. Table 4 shows the content ratio of The rod dimensions were all 4.0φ × 400 mm, and the welding conditions were DC reverse polarity and welding current 170A. At the time of welding, at the time of welding, preheat the rail welding groove to 400 to 500 ° C,
The multi-layer welded joint of 5 passes or more was evaluated.

Table 5 collectively shows the test evaluation results. Welding workability mainly depends on the stability of the arc, the amount of slag generated,
The slag characteristics and the amount of spatter were observed, and those having no practical problem were evaluated as ◯, and those having a problem were evaluated as x. Regarding wear resistance, damage resistance, and flaking resistance as usage performance, the average hardness, strength, and ductility were obtained by a strength test, and the quality was judged by indirect evaluation.
It was calculated at two levels. Furthermore, the specific resistance value, which is the cause of the signal failure, was also paid attention to, and those having an excessively large specific resistance value and clearly causing a problem were evaluated as x. In addition, micro test pieces of cross section at the center of the welded specimen were taken, and after polishing / etching, cracks and microstructure were evaluated by microscopic inspection.

The welding rod symbols B-1 to B shown in the examples of the present invention
It was confirmed that -15 had a good welding workability, had sufficient wear / damage resistance and anti-flaking properties, and had no problem in electric conduction properties, and could be used practically.

On the other hand, in B-18 shown in the comparative example, the amount of metal fluoride exceeds the upper limit of the present invention.
On the contrary, in No. 1, since the amount of rutile was below the lower limit of the present invention, the slag was liable to flow, causing instability in the molten pool formation, and welding workability was a problem. Further, since the amount of carbonate of B-16 exceeds the upper limit of the present invention, and the coverage of B-18 greatly exceeds the upper limit, the amount of slag is large and stable welding cannot be performed in either case. . On the contrary, in the case of B-21 having a coverage rate of not more than the lower limit, the arc protection cylinder was not sufficiently formed, spatter was often generated, and satisfactory welding such as blow hole and pit generation was impossible.
Furthermore, B-19, B-22 and B-23 are both rutile,
Since the combination of the main raw materials of the carbonate and the metal fluoride is out of the scope of the present invention, the slag fluidity deteriorates, arc instability is exhibited, and welding workability is a problem.

B-17, B-19, B- shown in the comparative examples
Nos. 20 and B-22 are those in which a strengthening element or a carbide-forming element in a bainite-based structure is added in combination in excess of the upper limit of the present invention, but these harden the weld metal more than necessary or partially crack. The resulting abnormal structure showed wear resistance, damage resistance, and flaking resistance, and good results could not be expected. Further, these also have a high specific resistance value and are impractical from the viewpoint of electric conduction characteristics. On the other hand, B-16, B-18, and B-21 are conversely C, Mn, and C.
Although the main components such as r are set to be equal to or lower than the lower limit of the present invention, the structure is sound, but the hardness and strength are not at a sufficient level, and wear resistance / damage resistance or flaking resistance It was confirmed that it was inferior in terms of sex and was impractical.

[0036]

[Table 3]

[0037]

[Table 4]

[0038]

[Table 5]

[0039]

[Table 6]

[0040]

As described above, the Cr-M according to the present invention is used.
The o-type coated arc welding rod for rails has excellent joint performance in terms of wear resistance and surface damage resistance, and also has good welding workability. It is a high-strength bainite-based rod under development for high-speed railways. It provides welding technology that supports the promotion of rail application, and its industrial value is extremely large.

[Brief description of drawings]

FIG. 1 is a cross-sectional view of rail steel.

[Explanation of symbols]

 1 Rail foot 2 Rail abdomen 3 Rail head 4 Rail head surface

[Procedure amendment]

[Submission date] June 15, 1994

[Procedure Amendment 1]

[Document name to be amended] Statement

[Correction target item name] 0020

[Correction method] Change

[Correction content]

Next, the reason for defining the range of each alloy component in the total metal in the welding rod will be described. C is medium C-
It is an essential component for forming in the weld metal a bainite structure in which fine precipitates similar to those of Cr-Mo rail steel are dispersed and precipitated. As the C content of the deposited metal increases, the hardness and tensile strength and thus the plastic deformation resistance increase, so that the wear resistance and flaking resistance of the weld metal can be improved. When the C content of the total metal in the welding rod is less than 0.1%, the C of the weld metal of the obtained joint is
In some cases, the amount becomes less than 0.1%, and the absolute amount of precipitates formed in the bainite structure of the base becomes insufficient, resulting in insufficient strength as well as deterioration in wear resistance and flaking resistance. On the other hand, when the C content of the total metal in the welding rod exceeds 0.39%, the C content of the weld metal of the obtained joint is 0.35%.
It becomes super, and a brittle structure is formed in association with Cr and Mo essential addition elements. Further, in terms of electrical conductivity, too, the specific resistance value becomes excessively large, so that it cannot be used as a welded joint.
It was defined as ~ 0.39%.

[Procedure Amendment 2]

[Document name to be amended] Statement

[Correction target item name] 0026

[Correction method] Change

[Correction content]

Since Nb is a component that promotes transformation, it has an effect of preventing harmful martensite generated during cooling after welding. Therefore, the Nb content of the weld metal is 0.
It is necessary that the content be 01% or more, preferably 0.015% or more. However, the Nb content of the weld metal is 0.07%
If it exceeds 1.0, coarse carbon / nitrides are produced, and the toughness and fatigue strength are reduced. Therefore, the Nb content of the total metal in the welding rod is specified to be 0.02 to 0.1% in consideration of the coverage.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Koichi Uchino 1-1, Toibata-cho, Tobata-ku, Kitakyushu, Kitakyushu, Fukuoka New Nippon Steel Corporation Yawata Works

Claims (2)

[Claims] 1. A coating composition containing 25 to 45% by weight of carbonate, 15 to 30% of metal fluoride, 3 to 9% of rutile, and the balance of coating agent and arc stabilizer, based on the total weight of the coating agent. The coating agent is coated in an amount of 20 to 30% with respect to the total weight of the welding rod, and each component occupying the total metal in the welding rod is C: 0.1 to 0.1% by weight.
0.39%, Si: 0.35-0.9%, Mn: 0.7
5 to 2.0%, Cr: 0.9 to 2.5%, Mo: 0.1
~ 0.6%, the balance consisting of Fe and inevitable impurities, Cr-Mo system coated arc welding rod for rails. 2. The coating composition contains 25 to 45% by weight of carbonate, 15 to 30% of metal fluoride, 3 to 9% of rutile, and the balance of coating agent and arc stabilizer with respect to the total weight of the coating agent. The coating agent is coated in an amount of 20 to 30% with respect to the total weight of the welding rod, and each component occupying the total metal in the welding rod is C: 0.1 to 0.1% by weight.
0.39%, Si: 0.35-0.9%, Mn: 0.7
5 to 2.0%, Cr: 0.9 to 2.5%, Mo: 0.1
~ 0.6%, V: 0.02-0.15%, Nb:
0.02-0.1%, Cu: 0.2-0.5%, Ni:
0.5 to 3% of 1 type or 2 types or more, with the balance being Fe
And Cr- characterized by comprising unavoidable impurities
Coated arc welding rod for Mo-based rails.