JP2587487B2 - Steel material with welds - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a steel material having a welded portion, and more particularly, to a welded portion formed by welding or repairing a steel material (welded joint or weld repaired portion). The present invention relates to a steel material having the following characteristics, that is, a welded joint of a steel material, which is applied to a marine structure or a ship in which the steel material is used as a structural member, particularly when a marine structure or a ship operated in an icy sea area is being constructed or in operation.

(Prior Art) Offshore structures and ships are painted and operated, but during operation, the paint may come off due to collision with driftwood or the like. In particular, in the case of a marine structure or a ship such as an icebreaker operated in an ice sea area, the paint is easily peeled off by the collision of ice.

When the paint comes off, the steel is exposed to seawater and becomes corrosive. In particular, if the coating on the welded portion of the steel material is peeled off, deep groove-shaped local corrosion (hereinafter referred to as grooved corrosion) will occur in the weld metal (hereinafter referred to as Depo) or the weld heat affected zone (hereinafter referred to as HAZ). This is a serious problem that is caused by the corrosion and damage is required.

For example, “Iron and Steel, S1266 (1986)” shows that ferrite-pearlite steel with low welding heat input is HA
It is shown that groove corrosion occurs in the Z part.

Regarding the prevention of such corrosion, see "Scandinaviam Journal o
f Metallurgy, vol.7 (1978), P.11 ”includes a normalized high-strength steel with a ferrite-pearlite structure: HT-50.
When welding steel, Mn content in steel is 1.1% to prevent HAZ corrosion
It is necessary to use a Cu-Ni-containing material as the welding material to prevent the HAZ part from becoming a low-temperature transformation structure by increasing the welding heat input and to prevent the groove corrosion at the Depo part. (Hereinafter, such a method is referred to as “prior art A”).

Also, Japanese Patent Application Laid-Open No. 60-228618 proposes a method of welding a quenched and tempered steel material and then locally tempering the surface layer of the welded portion (hereinafter referred to as prior art B).

(Problems to be Solved by the Invention) However, in the prior art A, since the Mn content in the steel needs to be less than 1.1%, it is difficult to secure the strength of the steel material.
Further, since it is necessary to increase the welding heat input, there is a problem that ordinary manual welding cannot be applied.

The prior art B requires heat treatment before and after welding, so that the production cost is high, the construction period is long, and the local tempering process after welding is complicated, so that the workability is reduced and the tempering reliability is increased. There is a problem that lacks.

The present invention has been made in view of such circumstances, and has as its object to solve the above problems of the prior art A and the prior art B, to increase the manufacturing cost and the construction period, and to improve the workability. A welded joint made of steel that can be obtained without lowering, ensures the required high strength, is excellent in groove corrosion resistance, and can be applied to manual welding in production, that is, a welded portion (steel welded joint and / or Or a welded part).

(Means for Solving the Problems) In order to achieve the above object, a steel material having a weld according to the present invention has the following configuration.

That is, the steel material having a welded portion according to claim 1 is obtained by welding a rolled steel material having a bainite phase-containing structure by controlled rolling, accelerated cooling, and steel having a C equivalent of 0.30 to 0.38% determined by the following equation. A steel material having a weld portion, wherein the amount of Ni in the weld metal at the weld portion is a value satisfying the following expression.

C equivalent = C amount + Si amount / 24 + Mn amount / 6 + Ni amount / 40 + V amount / 14…
... However, in the formulas, C content, Si content, Mn content, Ni content and V
All amounts are in wt%.

−0.3 ≦ Ni (D) −Ni (M) ≦ 0.8 where Ni (D) is the Ni content (%) in the weld metal, and Ni (M) is the Ni content (%) in the base steel material. ).

The steel material having a weld according to claim 2, wherein the steel is C:
0.02 ~ 0.12wt%, Si: 0.05 ~ 0.50wt%, Mn: 1.10 ~ 2.00wt
%, Sol.Al: 0.005 to 0.050 wt%, Ni: 0.01 to 5.00 wt%, Nb: 0.
005 ~ 0.100wt%, Ti: 0.005 ~ 0.020wt%, N: 0.0020 ~ 0.006
The steel material having a welded portion according to claim 1, which contains 0 wt% and the balance has a composition consisting of iron and unavoidable impurities.

The steel material having a weld according to claim 3, wherein the steel is:
C: 0.02-0.12wt%, Si: 0.05-0.50wt%, Mn: 1.10-2.00wt
%, Sol.Al: 0.005 to 0.050 wt%, Ni: 0.01 to 5.00 wt%, Nb: 0.
005 ~ 0.100wt%, Ti: 0.005 ~ 0.020wt%, N: 0.0020 ~ 0.006
0 wt%, Cu: 0.05-1.00 wt%, V: 0.005-0.
The steel material according to claim 1, wherein the steel material contains one or more selected from 100 wt%, B: 0.0005 to 0.0030 wt%, and the balance has a composition consisting of iron and unavoidable impurities. .

The steel material having a weld according to claim 4, wherein the steel is C:
0.02 ~ 0.12wt%, Si: 0.05 ~ 0.50wt%, Mn: 1.10 ~ 2.00wt
%, Sol.Al: 0.005 to 0.050 wt%, Ni: 0.01 to 5.00 wt%, Nb: 0.
005 ~ 0.100wt%, Ti: 0.005 ~ 0.020wt%, N: 0.0020 ~ 0.006
1 wt. It is a steel material having a welded portion according to the claims.

The steel material having a weld according to claim 5, wherein the steel is C:
0.02 ~ 0.12wt%, Si: 0.05 ~ 0.50wt%, Mn: 1.10 ~ 2.00wt
%, Sol.Al: 0.005 to 0.050 wt%, Ni: 0.01 to 5.00 wt%, Nb: 0.
005 ~ 0.100wt%, Ti: 0.005 ~ 0.020wt%, N: 0.0020 ~ 0.006
0 wt%, Cu: 0.05-1.00 wt%, V: 0.005-0.
100 wt%, B: one or more selected from 0.0005 to 0.0030 wt%, Ca: 0.0005 to 0.0030 wt%, rare earth element: 0.005
Contains one or two selected from ~ 0.030wt%,
The first having a composition in which the balance consists of iron and unavoidable impurities
It is a steel material having a welded portion according to the claims.

(Operation) In the present invention, a hot-rolled steel material manufactured under various conditions is used as a base material, and the base material is welded and joined using various welding materials to obtain a welded joint. It has been completed based on the findings obtained by carefully examining the effects of components and microstructure mainly on groove corrosion resistance and strength. Hereinafter, the use will be described based on this finding.

In other words, regarding the corrosion of welded joints,
In the case of a pearlite structure, groove-like corrosion occurs at the HAZ. This is because the HAZ portion has a low-temperature transformation structure (martensite and / or bainite structure) that is very different from the base material structure, so that the potential difference between the base material and the HAZ portion increases to promote corrosion. On the other hand, when the base steel has a bainite phase-containing structure, both the base material and the HAZ have a low-temperature transformation structure, and the potential difference between the base material and the HAZ is relatively small, so that only the HAZ is particularly corroded. Rather, mild general corrosion occurs, which reduces the corrosion depth. Therefore, if the base metal structure is a low-temperature transformed structure almost similar to the structure of the HAZ portion, groove-like corrosion in the HAZ portion can be prevented.

Therefore, in the steel material having a welded portion according to the present invention, a rolled steel material in which the structure of the steel is a structure containing a bainite phase is welded. That is, it has a welded portion formed by welding such a rolled steel material.

For example, when the welded joint is immersed in seawater for 4 months, when the base steel has a ferrite-pearlite structure, groove-like corrosion (4) occurs in the HAZ (2) as shown in FIG. On the other hand, when the base steel has a bainite phase-containing structure, it is uniformly corroded from the HAZ portion (2) to the base material portion (1) as shown in FIG. 2, and the corrosion (4) has a small depth. . In addition, since the welding material is the same for both materials and the Ni content is high,
No corrosion occurred in the Depo part (3). In Fig. 2 (5)
Indicates the surface position of the welded joint before immersion in seawater.

The corrosion of the welded joint is caused not only by the potential difference between the base material and the HAZ portion as described above, but also by the potential difference between the base material (including the HAZ portion) and the Depo portion. Corrosion due to a potential difference between the base material and the Depo portion is often caused by a difference in structure. Since the welding material is used in consideration of strength, toughness, etc., the composition of the depo portion changes depending on the type of the welding material.

Incidentally, the composition of the steel according to the present invention will be described later in detail, but is set mainly from the viewpoint of securing the strength, and the composition is as described above. Among such steel components, Ni most affects the corrosion, and the larger the difference in the amount of Ni between the base material and the Depo portion, the more easily groove-like corrosion due to the potential difference between the base material and the Depo portion occurs. Become. Note that the groove-like corrosion occurs on the side where the amount of Ni is low.

Groove corrosion based on the above-mentioned Ni content is less likely to occur when the difference in Ni content is reduced. Here, the difference between the Ni content (%) of the base steel: Ni (M) and the Ni content (%) of the depo portion: Ni (D), that is, Ni (D) -Ni (M) is -0.3. When set to ~ 0.8,
Groove corrosion can be prevented from occurring.

Therefore, in the steel material having a welded portion according to the present invention, the Ni content in the weld metal (that is, Ni (M)) is −0.3 ≦ Ni (D) −Ni
The value satisfies (M) ≦ 0.8. Such adjustment of the amount of Ni can be performed by selecting and welding a welding material based on the amount of Ni in the base steel.

For example, when the above-described welded joints having various Ni content differences are immersed in seawater for 4 months, Ni (D) ≦ Ni, as shown in FIG.
In the case of (M), only the Depo part corrodes and Ni (M) -Ni (D)
Becomes large, groove corrosion occurs. When Ni (D) ≧ Ni (M), only the HAZ portion corrodes, and when Ni (D) −Ni (M) increases, groove corrosion occurs. In FIG. 3, ● shows the results when the base steel has a bainite phase-containing structure, and ○ shows the results when the base steel has a ferrite-pearlite structure.

As can be seen from FIG. 3, in order to substantially prevent groove-like corrosion in the HAZ, Ni (D) −Ni (M) ≦ 0.8 when the base steel has a structure containing a bainite phase. However, in the case of a ferrite-pearlite structure, Ni (D) -Ni (M)
It must be ≦ 0.2. Therefore, in the former case, Ni (D)
The range of -Ni (M) is good, but in the latter case, Ni
Since the range of (D) -Ni (M) is narrow, there remains a problem that welding work becomes extremely difficult.

In consideration of the actual welding workability as described above, the base steel must have a bainite phase-containing structure. Here also, there is a reason why the structure of the steel material is previously set to the structure containing the bainite phase. In other words, in order to prevent groove corrosion, it is necessary that the steel material has a bainite phase-containing structure before welding and that -0.3≤Ni (D) -Ni (M) ≤0.8 after welding. The effect of both of these provides a practical groove corrosion technique.

In order to obtain a steel material having such a bainite phase-containing structure, in the present invention, C equivalent (= C amount + Si amount / 24 + Mn) is used as steel.
The amount of steel + Ni amount / 40 + V amount / 14) is adjusted to 0.30 to 0.38 wt%, and the steel is rolled by controlled rolling and accelerated cooling. That is, the rolled steel material obtained by this is used. Here, control rolling
With accelerated cooling, compared to the case of normal hot rolling, hot rolling by lowering the rolling finish temperature, cooling after the hot rolling is performed by rapid cooling,
It is intended to facilitate bainite transformation.

The reasons for setting the upper and lower limits of the C equivalent will be described. C equivalent is 0.30
If it is less than wt%, the steel structure becomes a ferrite / pearlite structure, and bainite transformation is apt to occur, and sufficient strength cannot be obtained. If it exceeds 0.38 wt%, welding cracks are liable to occur when the constraint is large or when preheating is not performed. Also, when low heat input welding such as manual welding is applied, the HAZ portion has a martensite structure, and unlike the base metal structure, groove-like corrosion occurs.

The rolling finishing temperature is preferably set to 700 to 850 ° C.
If the temperature exceeds 850 ° C., the toughness deteriorates, and if the temperature is lower than 700 ° C., bainite transformation hardly occurs. The cooling rate after hot rolling is preferably 2 to 20 ° C / min. If the temperature is lower than 2 ° C./min, bainite transformation hardly occurs. If the temperature exceeds 20 ° C./min, martensitic transformation occurs, and the ductility of the steel material is reduced and the steel material is easily deformed.

Regarding the composition of the steel, C: 0.02 to 0.12 wt%, Si: 0.05 to 0.
50wt%, Mn: 1.10 ~ 2.00wt%, Sol.Al: 0.005 ~ 0.050wt%, N
i: 0.01 ~ 5.00wt%, Nb: 0.005 ~ 0.100wt%, Ti: 0.005 ~ 0.0
It is desirable to contain 20 wt%, N: 0.0020 to 0.0060 wt%, with the balance being iron and unavoidable impurities. This is because the steel material can surely have a bainite phase-containing structure, can have high strength and high toughness, and can have good weldability. The reason for setting the upper and lower limits in this case will be described below.

C is effective for improving the strength, but if it is less than 0.02 wt%, sufficient strength cannot be obtained, and if it exceeds 0.12 wt%, the weldability and the toughness of the HAZ portion decrease.

Si is effective for deoxidation and strength improvement, but if it is less than 0.05 wt%, a sufficient deoxidizing effect cannot be obtained, and if it exceeds 0.50 wt%, the weldability decreases.

Although Mn is effective for improving the strength, 1.10 wt% or more is necessary for securing sufficient strength, and if it exceeds 2.00 wt%, the weldability is reduced.

Al must be at least 0.005wt% for deoxidation,
If the content exceeds 0.050 wt%, the toughness of the HAZ portion is reduced.

Ni is effective in improving strength and low-temperature toughness, but 0.01 wt%
% Is ineffective, and if it exceeds 5.00 wt%, the ratio of the strength to the amount of expensive Ni added (that is, the economic effect index) deteriorates.

Nb is effective in improving toughness by refining the structure, increasing the hardenability of solid-solution Nb and increasing the strength by precipitation of Nb (C, N), and introducing a bainite phase-containing structure, but less than 0.005 wt%. This is because the effect is small, and if it exceeds 0.100 wt%, the toughness of the HAZ portion is reduced.

Since Ti is finely precipitated as TiN and prevents austenite grain coarsening, it is effective in improving the toughness of steel materials.In addition, during cooling after welding, TiN becomes a ferrite transformation nucleus in the HAZ part, so the toughness of the HAZ part is improved. In addition, since it suppresses martensitic transformation, even when low heat input welding such as manual welding is applied, there is an effect that the HAZ portion can have a bainite phase-containing structure. This is because the effect is small, and if it exceeds 0.020 wt%, the precipitation amount of hard TiN becomes too large, and the ductility of the steel material decreases.

N is necessary for bonding with Ti to form the above TiN, but if less than 0.0020 wt%, the above effects cannot be obtained.
If the content exceeds 0.0060 wt%, the amount of TiN becomes too large, and the ductility of the steel material decreases.

When high strength and high ductility are required, in addition to the above elements, one or more selected from Cu, V, B, Ca, and rare earth elements (hereinafter referred to as REM) are contained in 0.0005 to 1.00 wt%. It is good to let. In this case, Cu is 0.05 to 1.00 wt%, and V is 0.005%.
~ 0.100wt%, B is 0.0005 ~ 0.0030wt%, Ca is 0.0005 ~ 0.00
It is preferable that 30% by weight and REM be in the range of 0.005 to 0.030% by weight. The reasons for setting the upper and lower limits when one or more kinds are contained will be described below.

This is because Cu has the effect of improving the strength without lowering the toughness of the HAZ, but if less than 0.05 wt%, the effect cannot be obtained, while if it exceeds 1.00 wt%, the weldability deteriorates.

V is effective for improving the strength, but if less than 0.005 wt%, the effect cannot be obtained, and if it exceeds 0.100 wt%, the weldability is inferior.

Ca and REM have the effect of controlling the morphology of MnS inclusions and are effective in improving toughness and crack resistance, but Ca: 0.0005w
Less than t%, REM: less than 0.005wt%, the effect is not obtained,
If Ca: more than 0.0030 wt%, REM: more than 0.030 wt%, inclusions increase,
This is because the toughness and the crack resistance are rather reduced.

Since the present invention involves welding a rolled steel material subjected to controlled rolling and accelerated cooling in the manufacturing process, the number of steps is not increased as in the prior art B, and the present invention can be carried out in a rolling line. Therefore, it does not lead to an increase in manufacturing cost / construction period and a decrease in workability.

(Example) After heating steel having various compositions to 1150 ° C., controlled rolling, accelerated cooling, and a plate thickness having a bainite phase-containing structure: 3
0 mm rolled steel was obtained. Here, the rolling rate of controlled rolling is 87
%, The finishing temperature of the rolling is 750 ° C, and the cooling rate after hot rolling is 10 ° C /
min.

For comparison, an air-cooled one was also used instead of the above-mentioned accelerated cooling. Further, instead of the above-mentioned controlled rolling / accelerated cooling, rolling / air cooling was also performed by a usual method.

The above-mentioned rolled steel materials were welded using various welding materials to obtain welded joints (welded joints according to examples of the present invention and welded joints according to comparative examples). Here, welding is performed by manual welding or SA
The welding heat input was varied by W (submerged arc automatic welding). Also, the Ni amount between the base material and the Depo portion was variously changed by variously changing the Ni amount of the Depo portion. Before obtaining a welded joint, an oblique Y-shaped weld cracking test was performed to determine a preheating temperature for preventing cracking.

For the above welded joints, check the Ni content difference, tensile test,
A V notch impact test, a structure observation, and a corrosion resistance test by immersion in seawater for 4 months were performed.

Tables 1 to 3 show steel compositions, C equivalents, and rolling / cooling methods. Table 4 shows the strength of the base material (0.2% proof stress, tensile strength)
It also shows the impact fracture surface transition temperature, welding crack prevention preheating temperature, and the impact value of the HAZ. Table 5 shows the types of welding materials and welding methods, the welding heat input, the Ni content in the Depo portion, the Ni content difference, and the corrosion resistance. The corrosion resistance is based on the thickness of the Depo part.
The value was obtained by subtracting the HAZ plate thickness. In these tables, those of Experiment Nos. 1, 4, 5, 6, 9, 11, 14, and 16 show the properties such as the steel composition and strength of the welded joint according to the example of the present invention, and those of Experiment No. 2 , 3,7,8,10,12,13,15,17,18 are characteristics such as steel composition and strength of the welded joint according to the comparative example.

As can be seen from these tables, among the welded joints according to the comparative examples, the welded joints according to Experiments Nos. 2, 3 and 10 have good properties of the base steel. However, because the amount of Ni in the Depo part is excessive,
The value obtained by subtracting the thickness of the HAZ part from the thickness of the Depo part after the corrosion resistance test is large, and the HAZ part is deeply corroded. This is H
This indicates that groove corrosion has occurred in the AZ portion.

Conversely, the welded joints according to Experiments Nos. 15 and 17 had a low Ni content in the Depo portion, and the Depo portion was deeply corroded, indicating that groove corrosion occurred in the Depo portion. .

The welded joints according to Experiments Nos. 7, 8, 12, and 13 are the cases where rolled steel materials obtained by air cooling or normal rolling / air cooling after controlled rolling are used. The structure does not become a bainite phase-containing structure, but becomes a ferrite-pearlite structure, so that the steel material strength is low and the HAZ portion is deeply corroded. The reason why the groove-like corrosion occurred in the HAZ portion is that the steel structure is a ferrite-pearlite structure, but the Ni content in the Depo portion is excessive and the difference from the Ni content in the HAZ portion is large. This accelerates the growth of such groove corrosion.

The welded joint according to Experiment No. 18 has a steel composition different from the composition according to the present invention, and particularly has a large amount of C. Therefore, the preheating temperature for preventing cracking is high and the weldability is poor, and the toughness of the HAZ is poor. Furthermore, since rolling and cooling after rolling are usually performed by rolling and air cooling, the steel structure does not become a bainite phase-containing structure, but becomes a ferrite pearlite structure, so the steel material strength is low and the HAZ part is deeply corroded. I have.

On the other hand, the welded joints according to Experiments Nos. 1, 4, 5, 6, 9, 11, 14, and 16 (welded joints according to the examples of the present invention) show the properties, weldability, and HAZ Good toughness. In addition, the steel material structure is a structure containing a bainite phase, and the Ni content in the depo part is
The difference between the Ni amount in the HAZ portion and the plate thickness in the Depo portion and the HAZ portion after the corrosion resistance test is small. This is HAZ
It shows that no groove-like corrosion has occurred in the part and the Depo part.

(Effect of the Invention) A steel material having a welded portion according to the present invention can be obtained without increasing production cost and construction time and lowering workability, and can secure required high strength of steel material and have high strength. At the same time, it is excellent in groove corrosion resistance of the welded portion of steel. Further, in the production, a welding method having a low welding heat input such as a manual welding method can be applied, and even in such a case, the required high strength and groove corrosion resistance as described above can be obtained. Therefore, welded steel structures, such as marine structures and ships, which have the required high strength and excellent groove-like corrosion resistance without deteriorating economic efficiency and workability, and have long life and excellent safety. Can be obtained.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view of a welded joint showing the state of groove corrosion after immersing the welded joint in seawater for 4 months when the base metal structure is a ferrite / pearlite structure, and FIG. Fig. 3 shows the groove corrosion state after immersing the welded joint in seawater for 4 months in the case of the bainite phase-containing structure, and Fig. 3 shows the difference in the Ni content of the welded joint (from the Ni content in the Depo portion to the Ni content in the HAZ portion). It is a figure which shows the relationship between the degree of corrosion after the seawater immersion of the welded joint for 4 months (the value which subtracted the HAZ part thickness from the Depo part thickness). In FIG. 3, ● shows the results when the base steel structure is a structure containing a baitite phase, and ○ shows the results when the base steel structure is a ferrite-pearlite structure. (1) Base steel, (2) HAZ, (3) Depo
Part, (4) Corrosion part, (5) ... Surface position of welded joint before immersion in seawater

Claims (5)

(57) [Claims] 1. The C equivalent obtained by the following equation is 0.30 to 0.38.
% Is a steel having a welded portion obtained by welding a rolled steel having a bainite phase-containing structure by controlled rolling and accelerated cooling of a steel having a Ni content in the weld metal of the welded portion satisfying the following formula. A steel material having a welded part. C equivalent = C amount + Si amount / 24 + Mn amount / 6 + Ni amount / 40 + V amount / 14…
... However, in the formula, the amounts of C, Si, Mn, Ni and V are all values in wt%. −0.3 ≦ Ni (D) −Ni (M) ≦ 0.8 where Ni (D) is the Ni content (%) in the weld metal, and Ni (M) is the Ni content (%) in the base steel material. ). 2. The steel according to claim 1, wherein C: 0.02-0.12 wt%, Si: 0.05-0.
50wt%, Mn: 1.10 ~ 2.00wt%, Sol.Al: 0.005 ~ 0.050wt%, N
i: 0.01 ~ 5.00wt%, Nb: 0.005 ~ 0.100wt%, Ti: 0.005 ~ 0.0
The steel material having a weld according to claim 1, wherein the steel material contains 20 wt%, N: 0.0020 to 0.0060 wt%, and has a balance of iron and unavoidable impurities. 3. The steel according to claim 1, wherein C: 0.02-0.12 wt%, Si: 0.05-0.
50wt%, Mn: 1.10 ~ 2.00wt%, Sol.Al: 0.005 ~ 0.050wt%, N
i: 0.01 ~ 5.00wt%, Nb: 0.005 ~ 0.100wt%, Ti: 0.005 ~ 0.0
20 wt%, N: 0.0020 to 0.0060 wt%, and Cu: 0.05
~ 1.00wt%, V: 0.005 ~ 0.100wt%, B: 0.0005 ~ 0.0030wt%
The steel material having a weld according to claim 1, comprising one or more selected from the group consisting of: iron and unavoidable impurities. 4. The steel according to claim 1, wherein C: 0.02-0.12 wt%, Si: 0.05-0.
50wt%, Mn: 1.10 ~ 2.00wt%, Sol.Al: 0.005 ~ 0.050wt%, N
i: 0.01 ~ 5.00wt%, Nb: 0.005 ~ 0.100wt%, Ti: 0.005 ~ 0.0
20wt%, N: 0.0020 ~ 0.0060wt%, Ca: 0.00
The welded part according to claim 1, which contains one or two selected from 05 to 0.0030 wt% and a rare earth element: 0.005 to 0.030 wt%, with the balance having a composition consisting of iron and unavoidable impurities. Steel. 5. The steel according to claim 1, wherein C: 0.02-0.12 wt%, Si: 0.05-0.
50wt%, Mn: 1.10 ~ 2.00wt%, Sol.Al: 0.005 ~ 0.050wt%, N
i: 0.01 ~ 5.00wt%, Nb: 0.005 ~ 0.100wt%, Ti: 0.005 ~ 0.0
20 wt%, N: 0.0020 to 0.0060 wt%, and Cu: 0.05
~ 1.00wt%, V: 0.005 ~ 0.100wt%, B: 0.0005 ~ 0.0030wt%
One or more selected from Ca, 0.0005 to 0.0030
wt%, rare earth element: 1 selected from 0.005 to 0.030 wt%
The steel material having a weld according to claim 1, wherein the steel material contains one or two kinds and the balance has iron and inevitable impurities.