KR102352601B1 - Shielded metal arc welding material - Google Patents

Abstract

The present invention relates to a welding material. More particularly, the present invention relates to a shielded arc welding material capable of forming a weld part (weld joint part) with improved wear resistance and corrosion resistance. According to the present invention, the shielded arc welding material contains: 0.01 to 0.08 wt% of carbon (C); 0.3 to 0.9 wt% of silicon (Si); 0.8 to 1.6 wt% of manganese (Mn); 0.02 wt% or less of phosphorus (P) (excluding 0 wt%); 0.2 wt% or less of sulfur (S) (excluding 0 wt%); 0.1 to 0.7 wt% of nickel (Ni), 0.04 to 0.2 wt% of cobalt (Co); 0.2 to 0.5 wt% of copper (Cu), 0.1 to 0.7 wt% of molybdenum (Mo), 0.2 wt% or less of antimony (Sb) (excluding 0 wt%); the remaining Fe; and other unavoidable impurities.

Description

Covered arc welding material {SHIELDED METAL ARC WELDING MATERIAL}

The present invention relates to a welding material, and more particularly, to a covered arc welding material capable of forming a weld (weld joint) having improved wear resistance and corrosion resistance.

Recently, researches related to facilities to increase the desulfurization efficiency of environmental facilities of thermal power plants are continuing, and representatively, the development of materials applied to the gas gas heater (GGH), which is a heat exchange device at the front and rear ends of the desulfurization facility.

Existing GGH was located at the rear end of the electrostatic precipitator, but recently GGH is also placed on a part of the front end of the electrostatic precipitator. For this reason, as a steel material used in desulfurization facilities, steel materials having improved wear resistance as well as high strength at the same time are being developed, and welding materials used for welding such steel materials are also required to be developed.

Specifically, there is a need to develop a welding material that can simultaneously satisfy the strength and corrosion resistance of the weld joint when welding steel with improved high strength and wear resistance.

Korean Patent Publication No. 10-2098511

One aspect of the present invention is to provide a shielded arc welding material capable of securing a weld joint having excellent room temperature tensile strength and corrosion resistance during welding.

The subject of the present invention is not limited to the above. The subject of the present invention will be understood from the overall content of the present specification, and those of ordinary skill in the art to which the present invention pertains will have no difficulty in understanding the additional subject of the present invention.

One aspect of the present invention, by weight, carbon (C): 0.01 to 0.08%, silicon (Si): 0.3 to 0.9%, manganese (Mn): 0.8 to 1.6%, phosphorus (P): 0.02% or less ( Excluding 0%), Sulfur (S): 0.2% or less (excluding 0%), Nickel (Ni): 0.1 to 0.7%, Cobalt (Co): 0.04 to 0.2%, Copper (Cu): 0.2 to 0.5%, Molybdenum (Mo): 0.1~0.7%, antimony (Sb): 0.2% or less (excluding 0%), provides a shielded arc welding material containing the remaining Fe and other unavoidable impurities.

According to the present invention, it is possible to provide a weld joint with excellent corrosion resistance to sulfuric acid as well as tensile strength at room temperature. has the effect of providing.

1 shows a schematic diagram of a weld corrosion specimen used in the corrosion resistance test.

The present inventors have studied in depth to provide a welding material that can guarantee the physical properties of the weld joint during welding of these steels as the application of steel materials, particularly steels having excellent wear resistance and corrosion resistance, has recently been expanded to be applied to fossil power plants.

As a result, by optimizing the alloy composition of the welding material, it was confirmed that a weld joint having excellent room temperature tensile strength and corrosion resistance during welding using such a welding material can be formed, and the present invention has been completed.

Hereinafter, the present invention will be described in detail.

The shielded arc welding material according to an aspect of the present invention is, by weight, carbon (C): 0.01 to 0.08%, silicon (Si): 0.3 to 0.9%, manganese (Mn): 0.8 to 1.6%, phosphorus (P) : 0.02% or less (excluding 0%), Sulfur (S): 0.2% or less (excluding 0%), Nickel (Ni): 0.1 to 0.7%, Cobalt (Co): 0.04 to 0.2%, Copper (Cu): 0.2 ~0.5%, molybdenum (Mo): 0.1 to 0.7%, antimony (Sb): 0.2% or less (excluding 0%) may be included.

Hereinafter, the reason for limiting the alloy composition of the welding material provided in the present invention as above will be described in detail. Meanwhile, unless otherwise specified in the present invention, the content of each element is based on weight.

Carbon (C): 0.01~0.08%

Carbon (C) is an element advantageous for securing the strength of the welding material and the weld joint, and if the content is less than 0.01%, the target level of strength cannot be secured. On the other hand, when the content exceeds 0.08%, the corrosiveness to sulfuric acid is greatly reduced, and in particular, there is a fear that the degree of hardening of the weld metal formed during welding is increased, thereby promoting the occurrence of cracks in the weld.

Accordingly, the C may be included in an amount of 0.01 to 0.08%. More advantageously, it may contain 0.02% or more and 0.07% or less.

Silicon (Si): 0.3-0.9%

Silicon (Si) forms slag in the molten metal to protect the molten metal from the atmosphere and is an advantageous element for improving the strength of the weld metal. In order to sufficiently obtain the above-described effect, Si may be added in an amount of 0.3% or more, but when the content exceeds 0.9%, there is a problem in that corrosion properties to sulfuric acid are inferior.

Accordingly, the Si may be included in an amount of 0.3 to 0.9%.

Manganese (Mn): 0.8~1.6%

Manganese (Mn) is an element advantageous for improving the strength at room temperature of the weld joint, and for this purpose, it may be included in an amount of 0.8% or more. However, when the content exceeds 1.6%, the slag viscosity is lowered and there is a risk that the shape of the weld bead may be deteriorated.

Accordingly, the Mn may be included in an amount of 0.8 to 1.6%.

Phosphorus (P): 0.02% or less (excluding 0%)

The higher the content of phosphorus (P), the higher the strength improvement effect can be expected.

Accordingly, the P may be included in an amount of 0.02% or less, and 0% may be excluded in consideration of the unavoidably added level.

Sulfur (S): 0.2% or less (excluding 0%)

Sulfur (S) has the effect of improving corrosion resistance to sulfuric acid by combining with Cu in steel during welding to form a CuS stable film. However, when the content exceeds 0.2%, there is a problem of promoting high-temperature cracking of the weld joint.

Therefore, the S may be included in 0.2% or less, and 0% may be excluded.

More advantageously, it is preferable to include at least 0.005% in terms of improving the corrosion resistance of the weld joint.

Nickel (Ni): 0.1 to 0.7%

Nickel (Ni) is an element added to improve the corrosion resistance of the weld joint, but if its content is excessive, corrosion resistance to sulfuric acid may be significantly lowered, and as an expensive element, there is a problem that the manufacturing cost is greatly increased. , taking this into consideration, it may be included in an amount of 0.7% or less. In particular, in the present invention, there is an effect of securing a welded joint having a good surface and improved corrosion resistance by including the Ni at a maximum of 0.7%.

On the other hand, when the content of Ni is less than 0.1%, the effect of improving corrosion resistance cannot be expected.

Accordingly, the Ni may be included in an amount of 0.1 to 0.7%.

Copper (Cu): 0.2-0.5%

Copper (Cu) is an element advantageous for greatly improving corrosion resistance to sulfuric acid, and in order to sufficiently obtain this effect, it is preferable to include it in an amount of 0.2% or more. However, when the content exceeds 0.5%, the effect of improving the corrosion resistance by the addition of Cu is saturated, and there is a possibility of causing reheating cracks in the weld zone.

Accordingly, the Cu may be included in an amount of 0.2 to 0.5%.

Cobalt (Co): 0.04~0.2%

Cobalt (Co) is an element advantageous for improving corrosion resistance together with Cu, and has an effect of further improving corrosion resistance when combined with Co as compared to the addition of Cu alone.

In order to sufficiently obtain the above-described effect, it is advantageous to include Co in an amount of 0.04% or more, but when the content exceeds 0.2%, the effect of improving the corrosion resistance is saturated, and it causes an increase in the cost of the welding material.

Accordingly, the Co may be included in an amount of 0.04 to 0.2%.

Molybdenum (Mo): 0.1~0.7%

Molybdenum (Mo) is an element advantageous for improving the strength of the weld joint, and may be included in an amount of 0.1% or more in order to secure a target level of strength. On the other hand, when the content exceeds 0.7%, there is a problem in that the corrosiveness to sulfuric acid is rapidly reduced.

Accordingly, the Mo may be included in an amount of 0.1 to 0.7%.

Antimony (Sb): 0.2% or less (excluding 0%)

Antimony (Sb) is an element advantageous for improving corrosion resistance to sulfuric acid, and when combined with Cu and Co, the effect thereof may be further increased. However, when the content exceeds 0.2%, there is a problem in that the shape of the weld bead is poor and the welding workability is deteriorated by generating a large amount of spatter.

Therefore, the Sb may be included in 0.2% or less, and 0% is excluded. More advantageously, it may contain Sb in an amount of 0.01% or more.

The remaining component of the present invention is iron (Fe). However, since unintended impurities from raw materials or the surrounding environment may inevitably be mixed in the normal manufacturing process, this cannot be excluded. Since these impurities are known to any person skilled in the art in the manufacturing process, all details thereof are not specifically mentioned in the present specification.

The welding material of the present invention composed of the above alloy composition is applicable as a material of a welding rod used in a welding method using an arc, and specifically, as a welding rod of a welding method to which Shield Metal Arc Welding (SMAW) is applied. can be applied

When welding using the welding material according to the present invention, the welded joint formed has excellent room temperature tensile strength and corrosion resistance.

Specifically, the weld joint has room temperature tensile strength of 650 MPa or more, and when immersed in a 50% solution of sulfuric acid alone, the corrosion rate is 25 mg/cm ² /hr or less, and when immersed in a complex (28.5% sulfuric acid + 0.55% hydrochloric acid) solution Corrosion rate is 1.5mg/cm ² /hr or less, and it has excellent corrosion resistance properties.

Hereinafter, the present invention will be described in more detail through examples. However, it is necessary to note that the following examples are only intended to illustrate the present invention in more detail and are not intended to limit the scope of the present invention. This is because the scope of the present invention is determined by the matters described in the claims and matters reasonably inferred therefrom.

(Example)

A welding material having an alloy composition shown in Table 1 was prepared. High corrosion resistance steel for GGH using each welding material (by weight, 0.043C-0.015Si-0.28Cu-0.14Ni-0.10Sb-0.07Ti-0.15Sn-0.005S-0.002N, balance Fe and unavoidable impurities) was subjected to gas metal arc welding (GMAW). At this time, the welding was performed at speed: 10 cm/min, current: 130A, voltage: 21V.

The physical properties of the weld joint formed after welding according to the above were measured, and the results are shown in Table 2.

Specifically, to measure the tensile strength at room temperature, a tensile test piece was prepared according to the KS standard (KS B 0801) No. 4 test piece, and then a load was applied to each tensile test piece at room temperature until fracture occurred in the vertical direction of the weld to increase the tensile strength. was measured.

In addition, for corrosion resistance measurement, a specimen is taken in the shape as shown in FIG. 1, and then the specimen is immersed in a solution under the following corrosion conditions and taken out, and the time at which corrosion occurs from the immersion time, that is, the corrosion rate is measured It was evaluated from

○ Sulfuric acid alone corrosion condition: immersion in 70℃, 50wt% sulfuric acid solution for 1hr, 6hr, 24hr (measured separately for each hour)

○ Complex corrosion conditions: immersion in 60℃, 28.5wt% sulfuric acid + 0.55wt% hydrochloric acid solution for 6hrs and 24hrs (measured individually for each hour)

division Alloy composition (wt%) C Si Mn P S Ni Co Cu Mo Sb Comparative Goods 1 0.064 0.43 0.90 0.012 0.005 0.16 0.065 0.30 0.004 0.13 Comparative Goods 2 0.036 0.25 0.84 0.008 0.007 0.08 0.110 0.24 0.002 0 Comparative Good 3 0.049 0.53 0.69 0.011 0.010 0 0.042 0.24 0.002 0 Comparative Goods 4 0.057 0.48 0.79 0.010 0.009 0.11 0.120 0.20 0 0.21 Comparative Goods 5 0.028 0.63 0.75 0.015 0.012 0.15 0.053 0.35 0.01 0.14 invention material 1 0.048 0.90 1.32 0.016 0.011 0.53 0.100 0.27 0.25 0.20 Invention 2 0.024 0.82 0.95 0.005 0.006 0.38 0.044 0.37 0.32 0.15 invention 3 0.067 0.73 1.20 0.012 0.005 0.43 0.067 0.35 0.52 0.10 Invention 4 0.036 0.64 0.85 0.008 0.012 0.48 0.043 0.28 0.10 0.084 Invention 5 0.052 0.84 1.05 0.007 0.012 0.28 0.084 0.31 0.42 0.13

division room temperature tensile strength
(MPa) Sulfuric acid alone corrosion reduction
(mg/cm ² /hr) Composite corrosion reduction
(mg/cm ² /hr) Comparative Goods 1 607 28 2.5 Comparative Goods 2 542 52 3.8 Comparative Good 3 618 60 4.3 Comparative Goods 4 589 35 2.7 Comparative Goods 5 564 32 3.2 invention material 1 774 23 1.4 Invention 2 695 25 1.5 invention 3 762 18 0.9 Invention 4 669 21 1.1 Invention 5 732 15 0.7

As shown in Tables 1 and 2, in the case of Invention Materials 1 to 5, which were welded using a welding material having an alloy composition proposed in the present invention, the room temperature tensile strength of the weld joint formed after welding was high, and It can be seen that the corrosion resistance is excellent.

On the other hand, Comparative Materials 1 to 5, which were welded using a welding material that did not satisfy the alloy composition proposed in the present invention, had a low tensile strength at room temperature of a weld joint formed after welding of less than 660 MPa, and corrosion resistance to sulfuric acid was also poor. can check that

Claims (4)

By weight%, carbon (C): 0.01 to 0.08%, silicon (Si): 0.3 to 0.9%, manganese (Mn): 0.8 to 1.6%, phosphorus (P): 0.02% or less (excluding 0%), sulfur ( S): 0.2% or less (excluding 0%), Nickel (Ni): 0.1 to 0.7%, Cobalt (Co): 0.04 to 0.2%, Copper (Cu): 0.2 to 0.5%, Molybdenum (Mo): 0.1 to 0.7 %, antimony (Sb): 0.2% or less (excluding 0%), shielded arc welding material containing remaining Fe and other unavoidable impurities.
The method of claim 1,
The welding material is a shielded arc welding material containing antimony (Sb) in an amount of 0.01 to 0.2%.
The method of claim 1,
The weld joint obtained by welding using the welding material,
Covered arc welding material with a tensile strength of 650 MPa or more at room temperature.
The method of claim 1,
The weld joint obtained by welding using the welding material,
Covered arc welding material having a corrosion rate of 25 mg/cm ^{2 /hr or less when immersed in a 50% sulfuric acid solution and 1.5 mg/cm 2} /hr or less when immersed in a complex (28.5% sulfuric acid + 0.55% hydrochloric acid) solution.

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