JP2003013175A - Steel material superior in hydrogen-induced cracking resistance - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a high strength steel material superior in HIC(hydrogen induced cracking) resistance consisting of an inexpensive high-Mn steel used for linepipes, a cargo tanks, and pressure vessels, towers and tanks for petroleum refining. SOLUTION: The objective steel material has average Mn concentration lower in the central part of the plate thickness than in the whole steel, and maximum Mn concentration at the central part of the plate thickness, of 2.9 mass% or less.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to hydrogen-proof induction suitable for line pipes and cargo tanks used for transporting crude oil and natural gas containing hydrogen sulfide, or for pressure vessels and tanks for petroleum refining. The present invention relates to a steel material having excellent crackability.

[0002]

2. Description of the Related Art Line pipes and cargo tanks used for transporting crude oil and natural gas containing hydrogen sulfide, or steel materials used as pressure vessels and tanks for oil refining,
Hydrogen induced cracking (hereinafter referred to as HIC) is often a problem. HIC is a crack caused by hydrogen that has penetrated into steel when a steel material is used and corroded in an environment containing hydrogen sulfide.

Steel materials manufactured from continuous cast slabs, particularly steel sheets, have a high HIC sensitivity in the positive segregation zone at the center of the plate thickness. The reason is that in the positive segregation zone, the Mn and P concentrations are particularly higher than in the base material, and as a result, the positive segregation zone tends to be harder than the base material. Therefore,
Conventional hydrogen-induced cracking resistance (hereinafter referred to as HIC resistance)
A steel material excellent in segregation has a composition in which the hardness of the positive segregation zone is suppressed to a level at which HIC does not occur and segregation is difficult, that is, low C
-Based on low Mn system.

For example, Japanese Laid-Open Patent Publication No. 5-271766 discloses a low C content in order to improve center segregation of a continuously cast slab.
-Low Mn-Nb-To each of the base steels added with a small amount of Ti, 0.3% or less of Cr and Mo are added together, and after controlled rolling,
A method of accelerated cooling is shown. In addition, JP-A-11-
Japanese Patent No. 302776 discloses a method in which the contents of S, Mg, Ca and O of a low C-low Mn-Nb-Ti steel are strictly limited and controlled rolling is performed, followed by accelerated cooling.

However, in the methods disclosed in both of the above publications, M is an element which easily obtains high strength at low cost.
There was a problem that the upper limit of n had to be limited. Specifically, the upper limit of Mn content of steel shown in the former publication is 1.4%, and the upper limit of Mn content of steel shown in the latter publication is 1.5%. Therefore, instead of defining the upper limit of the Mn content, it is necessary to add expensive Cr or Mo or to control the complex contents of S, Mg, Ca and O. That is, these conventional inventions have no technical idea of obtaining a steel material which is made of an inexpensive high Mn steel and has excellent HIC resistance.

[0006] Japanese Unexamined Patent Publication (Kokai) No. 6-220577 discloses that HIC resistance in which the upper limit of the Mn content is 2.5% in which the Mn concentration in the segregated portion is regulated to 1.20 times or less the average Mn concentration in steel.
A high-strength steel sheet having excellent properties is shown. However, the high-strength steel sheet shown there is expensive C as an essential component.
Since it contains a large amount of u and Ni, it has a drawback of high cost. In addition, this publication describes expensive Cu and Ni.
No technical idea has been shown to improve the HIC resistance of an inexpensive high Mn steel containing no.

[0007]

DISCLOSURE OF THE INVENTION An object of the present invention is to provide a steel product used as a line pipe or a cargo tank used for transporting crude oil or natural gas containing hydrogen sulfide, or as a pressure vessel or tank for petroleum refining. It is an object of the present invention to provide a high-strength steel material that exhibits good HIC resistance even if the material steel is an inexpensive high Mn steel.

[0008]

The gist of the present invention resides in the following steel material having excellent resistance to hydrogen-induced cracking.

The average Mn concentration in the central part of the plate thickness is the average Mn in steel.
A steel material having a hydrogen-induced cracking resistance that is lower than the concentration and has a maximum Mn concentration of 2.9% by mass or less in the central portion of the plate thickness.

The above-mentioned steel material of the present invention has an average M of the plate thickness central portion.
It is desirable that the n concentration is 0.95 times or less of the average Mn concentration in the steel, and in this case, the HIC resistance is further improved.

Further, the above steel material of the present invention has a chemical composition
% By mass, C: 0.01 to 0.1%, Si: 0.01 to
0.5%, Mn: 0.8 to 2%, P: 0.025% or less, S: 0.002% or less, Ca: 0.0005 to 0.
005%, Ti: 0.005 to 0.05%, Nb: 0.
005-0.1%, sol.Al: 0.005-0.05
%, N: 0.01% or less, and the balance is preferably Fe and impurities. In this case, it is suitable for a line pipe or a pressure vessel.

In the steel material of the present invention, instead of part of Fe,
V: 0.2% or less, Cu: 0.5% or less, Ni: 0.5
% Or less, Cr: 3% or less, Mo: 1.5% or less, and B: 0.002% or less may be included.

[0013]

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, the reason why the steel material of the present invention is determined as described above will be described in detail by taking a steel sheet as an example.

In the conventional steel sheet, the concentration of the alloying element in the central portion of the sheet thickness has a concentration distribution as shown in FIG. Then, the concentration ratio (segregation degree) of the alloy element between the segregated portion at the center of the plate thickness and the other portion depends on the type of the alloy element and its concentration.

For example, Mn shown in FIG. 1 is one of the alloy elements with the highest degree of segregation among the various alloy elements used in the above-mentioned steel for applications, and the Mn concentration and C
The higher the concentration, the higher the degree of segregation. Therefore, in order to obtain a steel sheet having excellent HIC resistance, as described above, conventionally, there was no choice but to use a low C-low Mn system that is difficult to segregate.

However, if the concentration of the alloying element in the center of the plate thickness is lower than the concentration of the base metal, that is, as shown in FIG. 2, the center of the plate has a macro (macroscopic) negative segregation. If it is, it is micro (microscopic) in the negative segregation zone.
Even if a positive segregation zone is generated, it is expected that the degree of segregation itself will decrease due to the low concentration of alloying elements in the negative segregation zone, and the absolute value of the concentration of alloying elements in the positive segregation zone will not increase.

The reason why the Japanese sword is hard to break is that the hard cored bar is covered with the soft winding metal. Similarly, in the steel plate in which the hard positive segregation band is covered with the soft negative segregation band. However, it is expected that it is hard to break because of its hardness.
That is, as a result, it is expected that the HIC resistance of the high Mn steel in which the HIC resistance of the plate thickness center segregation portion was not good in the past is also improved.

Therefore, the inventor of the present invention has hitherto been able to obtain a good HI resistance.
Using high Mn steel, which was difficult to secure C property,
It was verified by experiments whether the HIC resistance is improved by macroscopically negatively segregating the center part of the plate thickness and covering the remaining positive segregation part in the negative segregation zone.

As a result, if the average Mn concentration in the central portion of the plate thickness is lower than the average Mn concentration in the steel and the maximum Mn concentration in the central portion of the plate thickness is 2.9 mass% or less, the average M in the steel is M.
The inventors have found that good HIC resistance can be ensured even with a steel material made of high Mn steel having an n concentration of more than 1.5% by mass, and have completed the present invention.

Further, the above-mentioned steel material of the present invention can be easily manufactured by applying reduction at the end of solidification during slab manufacturing by continuous casting. More specifically, for example,
At a position where the distance from the meniscus is about 3 m, the slab thickness is once changed to about 20 mm and bulging is performed, and then a slab thickness is reduced to about 10 to 20 mm from a position where the distance from the meniscus is 12 m to 17 m. Can be easily obtained by adding.

Maximum Mn concentration in the center of plate thickness: 2.9
% As will be apparent from the examples described below, when the maximum Mn concentration in the central part of the plate thickness exceeds 2.9%, the HI resistance is high.
C property becomes unsatisfactory. Therefore, the maximum Mn concentration in the central part of the plate thickness is set to 2.9% or less. Incidentally, it is preferably 2.4% or less, and in this case, HIC does not occur at all.

Average Mn Concentration in Plate Thickness Center: Lower than Average Mn Concentration in Steel As will be apparent from Examples described later, the maximum Mn concentration in the plate thickness center is 2.9%.
If the average Mn concentration in the central portion of the plate thickness is higher than the average Mn concentration in the steel, the HIC resistance becomes poor, even if it is less than or equal to 2.4%, which is preferable. Therefore, it was determined that the average Mn concentration in the central portion of the plate thickness is lower than the average Mn concentration in steel.

The fact that the average Mn concentration in the center of the plate thickness is lower than the average Mn concentration in the steel means that the center of the plate thickness is stably negatively segregated. The Mn concentration is preferably 0.95 times or less the average Mn concentration in steel.

Here, the plate thickness center portion means 1 / th of the plate thickness on both sides in the plate thickness direction from the plate thickness center of the final product steel plate.
It is 20 each, that is, a region of 1/10 of the plate thickness at the center of the thickness.

The average Mn concentration in the plate thickness center is the average value of Mn concentration in the plate thickness center region defined above, and is a value measured using MA (mapping analyzer) or EPMA. The average Mn concentration in the steel means the average Mn concentration of the entire steel and is equal to the ladle value.

In the steel material of the present invention, the average Mn concentration in the central portion of the plate thickness is lower than the average Mn concentration in the steel, and the maximum Mn concentration in the central portion of the plate thickness is 2.9 mass% or less,
There is no particular limitation on the chemical composition of steel. However, the chemical composition of the steel material according to the present invention which is desirable for line pipes and pressure vessels is as follows. In addition, "%" in the following description means "mass%" unless otherwise specified.

C: 0.01 to 0.1% C has a function of stably securing the strength of the steel material. However, if the content is less than 0.01%, it becomes difficult to secure the strength. On the other hand, if the content exceeds 0.1%, the peritectic region becomes difficult to continuously cast. Therefore, the C content is 0.0
It is desirable to be 1 to 0.1%. A more desirable range is 0.03 to 0.09%.

Si: 0.01 to 0.5% Si is necessary as a deoxidizing agent. However, if the content is less than 0.01%, a sufficient deoxidizing effect cannot be secured. On the other hand, if the content exceeds 0.5%, the toughness decreases. Therefore, it is desirable that the Si content is 0.01 to 0.5%. More desirable range is 0.05 to 0.3
5%.

Mn: 0.8-2% Mn has a function of stably securing the strength of the steel material.
Mn is also a relatively inexpensive element. However, if the content is less than 0.8%, it becomes difficult to secure the strength at low cost. On the other hand, when the content exceeds 2%, the Mn concentration in the positive segregation zone in the negative segregation zone in the central part of the plate thickness is
It becomes difficult to control the HIC resistance to 2.9% or less, which is favorable, and HIC is likely to occur in a wet H ₂ S environment. Therefore, the Mn content is preferably 0.8 to 2%. A more desirable range is 1.2 to 1.8%.

P: 0.025% or less P is an impurity element, and like the above Mn, positive segregation is likely to occur in the central portion of the plate thickness, and as a result, the positive segregation portion is hardened and HIC is likely to occur. Therefore, the lower the P content is, the more preferable it is, but excessive reduction causes an increase in cost. However, if the content is up to 0.025%, there is no particular problem. A desirable upper limit is 0.015%.

S: 0.002% or less S is an impurity element similar to the above P, and if the content exceeds 0.002%, MnS will be obtained even if the sulfide morphology is controlled by adding Ca as described below. Remains and HIC resistance
Sex is impaired. Therefore, the S content is 0.002%
The following is preferable. A more desirable upper limit is 0.00
It is 1% or less. The lower the S content, the better.

Ca: 0.0005 to 0.005% Ca has the action of controlling the morphology of sulfides, and HIC
Of MnS which is the starting point of But 0.000
If the content is less than 5%, the sulfide morphology control effect is poor, and if the content exceeds 0.005%, not only the sulfide morphology control effect is saturated, but also excess Ca inclusions cause toughness and HIC resistance. Spoil the sex. Therefore, the Ca content is preferably 0.0005 to 0.005%. A more desirable range is 0.001 to 0.003%.

Ti: 0.005 to 0.05% Ti fixes the impurity element N contained in the steel as TiN, prevents the toughness from decreasing due to free N, and
Has the effect of suppressing the growth of austenite grains during slab heating, promoting grain refinement, and improving toughness. But,
If the content is less than 0.005%, the above effect cannot be obtained, and if it exceeds 0.05%, the toughness is rather lowered. Therefore, the Ti content is 0.005-0.0.
5% is preferable. More desirable range is 0.01
Is 0.03%, and from the viewpoint of preventing the toughness from being deteriorated by free N, it is desirable to add Ti so that Ti / N is about 3.4.

Nb: 0.005 to 0.1% Nb has the function of refining the steel by carbide precipitation and improving the toughness. However, its content is 0.005
If it is less than 0.1%, the above effect cannot be obtained, and if it exceeds 0.1%, the toughness of the welded portion is lowered. Therefore, Nb
The content is preferably 0.005 to 0.1%. A more desirable range is 0.01 to 0.05%.

Sol.Al: 0.005-0.05% Al is necessary as a deoxidizing agent. However, if the sol.Al content is less than 0.005%, a sufficient deoxidizing effect cannot be secured. On the other hand, if the content exceeds 0.05%, the cleanliness and toughness of the steel material deteriorate. Therefore, it is desirable that the sol.Al content be 0.005 to 0.05%. More desirable range is 0.01 to 0.04%
Is.

N: 0.01% or less N is an impurity element similar to the above P and S, and when the content exceeds 0.01%, N is converted to T by the above Ti.
Even if fixed as iN, the toughness of the base material is lowered. Therefore, the N content is preferably 0.01% or less. A more desirable upper limit is 0.005%.
The lower the N content, the better.

The desirable chemical composition of the steel material for the line pipe and the pressure vessel is sufficient if the above is satisfied, but if necessary, one or more of the following elements are positively added and contained. It is preferable that it is one.

V: 0.2% or less (preferred lower limit at the time of positive addition: 0.01%) V not only improves the toughness by fine-graining the steel, but also the action of precipitated V carbides strengthens the steel. However, these effects can be obtained even when the content is at the impurity level, but become significant when the content is 0.01% or more. Therefore, if it is desired to obtain the above effect, it may be positively added and contained. But,
If the content of Ni exceeds 0.2%, the toughness of the welded portion is reduced. Therefore, the V content in the case of adding and containing is 0.0
It is desirable to be 1 to 0.2%. A more desirable range is 0.05 to 0.1%.

Cu: 0.5% or less (preferred lower limit during positive addition: 0.05%) Ni: 0.5% or less (preferred lower limit during positive addition: 0.
05%) Cr: 3% or less (preferred lower limit during positive addition: 0.1
%) Mo: 1.5% or less (preferred lower limit during positive addition: 0.
05%) B: 0.002% or less (preferred lower limit during positive addition:
0.0002%) These elements have the effect of improving the strength of steel,
This effect can be obtained even when the content of each element is at the impurity level, but Cu, Ni and Mo are 0.05% or more,
Cr becomes remarkable when the content is 0.1% or more. Therefore, in order to obtain the above effect, one or more of these elements may be positively added and contained. But C
If u and Ni are contained in excess of 0.5%, not only the effect is saturated, but also Ni is an expensive alloy element, which causes a cost increase. Also, Cr is 3%, M
If the content of o exceeds 1.5%, not only does the toughness of the welded portion decrease, but also Mo is an expensive alloying element, which causes a cost increase. Therefore, the Cu and Ni contents when both are added and contained are both 0.
005-0.05%, Cr content 0.1-3%, Mo
The content is preferably 0.05 to 1.5%. A preferable Cu and Ni content range is 0.1 to 0.3%,
The Cr content range is 0.25 to 2.5%, and the Mo content range is 0.1 to 1.2%. In addition, Cu, Ni, C
r and Ni also have an effect of improving corrosion resistance.

Next, preferable manufacturing conditions after manufacturing a slab by continuous casting of the steel material according to the present invention, which is desirable for line pipes and pressure vessels, will be described.

Heating temperature of slab: As described above, the slab obtained by applying the reduction at the final stage of solidification in order to discharge the concentrated molten steel with the increased degree of segregation from the axial center of the slab is subjected to rolling, forging, etc. However, if the heating temperature at that time is lower than 1050 ° C., the carbides in the slab may not sufficiently form a solid solution, and the desired strength may not be obtained after hot working. If the heating temperature is higher than 1250 ° C, the particles may be coarsened and the toughness may be lowered. Therefore, it is desirable that the heating temperature of the slab is 1050 to 1250 ° C. A more desirable range is 1100 to 1250 ° C.
Note that this is not the case when heat treatment is performed after hot working.

Finishing temperature of hot working: Recently, from the viewpoint of manufacturing cost reduction, the chemical composition and manufacturing conditions of steel are controlled so that desired strength and toughness can be obtained by hot working (rolling). Is common. However, hot working (rolling)
If the finishing temperature is less than 650 ° C, the deformation resistance of the steel increases, making it difficult to process (roll), and if it exceeds 900 ° C,
The structure of steel may not be sufficiently refined and desired strength and toughness may not be obtained as rolled. Therefore, the finishing temperature for hot working (rolling) is preferably 650 to 900 ° C. More preferred range is 700-850 ° C., after hot working, preferably a finishing temperature range when performing the accelerated cooling process described below _A r3 to 850 ° C., and more preferred range is _A r3 + 30 ℃ _~850 ℃ .

Accelerated cooling start temperature after hot working: Recently,
As mentioned above, even if the desired strength and toughness are obtained with hot working (rolling) as it is, accelerated cooling such as water cooling is performed after hot working (rolling) so as to achieve with a lower cost steel composition. It is more common to do However, when the accelerated cooling start temperature falls below the _Ar3 transformation point −30 ° C., the retained austenite at that time undergoes transformation hardening and HIC resistance and S resistance.
SC property may be impaired. Therefore, it is desirable that the start temperature of the accelerated cooling is set to the _Ar3 transformation point −30 ° C. or higher. A more desirable lower limit is in the range of the _{Ar 3} transformation point or higher.

Cooling rate of accelerated cooling: When the cooling rate at the center of the plate thickness is lower than 6 ° C./s, the effect of accelerated cooling is not obtained,
On the other hand, if the temperature exceeds 25 ° C / s, the steel will harden too much and the HI resistance
C property and SSC resistance may be impaired. Therefore, the cooling rate at the time of accelerated cooling is preferably 6 to 25 ° C./s at the cooling rate at the center of the plate thickness. A more desirable range is 10 to 20 ° C / s.

Accelerated cooling stop temperature: When the accelerated cooling stop temperature exceeds 550 ° C., there is no effect of accelerated cooling, and conversely,
If the temperature is lower than 350 ° C, the steel will harden too much and HIC resistance and S resistance
SC property may be impaired. Therefore, the stop temperature of the accelerated cooling is preferably set to 550 to 350 ° C. A more desirable range is 550 to 400 ° C.

Heat treatment after hot working: The heat treatment after hot working is not necessarily required, but heat treatment such as quenching-tempering treatment or normalizing treatment may be performed, in which case the toughness is further improved. The desired strength can be stably obtained. However, if the reheating temperature at that time is lower than 850 ° C., the carbides in the steel may not sufficiently form a solid solution and the desired strength may not be obtained. It may decrease. Therefore, the reheating temperature when performing heat treatment after hot working is 850 to 110.
It is desirable to set it to 0 ° C. A more desirable range is 900-
It is 1050 ° C. Note that the heat treatment after the hot working requires an extra process step, and the manufacturing cost increases accordingly. Therefore, it is not recommended from the viewpoint of reducing the manufacturing cost.

[0047]

EXAMPLE Four kinds of steels having the chemical compositions shown in Table 1 were melted and continuously cast to have a thickness of 238 mm and a width of 1800 mm.
When the slab is made into a slab, the slab thickness is once bulged by 20 mm at a position where the distance from the meniscus is 3 m, and then the slab is pressed under various conditions shown in Table 2 to reduce the Mn of the central part.
Slabs with various degrees of negative segregation were obtained. For comparison, bulging and reduction were not applied to some slabs.

Next, from the center of each obtained slab, a thickness of 150 m from which the center of thickness and width coincides with the center of the slab.
A block for rolling having a width of m and a width of 100 mm was cut out, subjected to hot rolling under the conditions shown in Table 2, and then subjected to accelerated cooling treatment or air cooling treatment under the conditions shown in Table 2 to obtain an average Mn segregation at the center of the plate thickness. Plate thickness 19.5 with various degrees and maximum Mn concentrations
mm and a width of 110 mm.

From each of the obtained steel plates, 100 mm × 100
mm total plate thickness specimens were collected and in accordance with the HIC test method specified in NACE T0284, 5 mass% NaC
It was immersed in a NACE TM0177 solution at a temperature of 25 ° C. of 1 + 0.5 mass% CH ₃ OOH + 1 atm H ₂ S saturation for 96 hours.

In the evaluation of the HIC test, the area of cracks due to HIC in the test piece after immersion was measured by C scanning with ultrasonic waves, and the crack area ratio (CAR) of HIC in the total area of the test piece was obtained. % Or less is HIC resistant
Good property, HIC resistance was unsatisfactory when it exceeded 3%.

The average Mn concentration at the center of the plate thickness and the maximum M
For the n concentration, the test piece after the above-mentioned CAR measurement was cut, and the plate thickness center portion, that is, 1.
Using an MA (mapping analyzer), the Mn concentration in a region of 0 mm and 20 mm on each side from the center of the plate width is 2
100,000 points were measured at a pitch of 0 μm, the average value of each measured value was taken as the average Mn concentration, and the maximum value among the measured values was taken as the maximum Mn concentration.

The above results are shown in Table 2 together with the yield strength YS (MPa) and tensile strength TS (MPa) of each steel sheet. The yield strength YS and the tensile strength TS are values obtained by taking tensile test pieces having an outer diameter of 6 mm from each steel sheet and conducting a tensile test at room temperature.

As can be seen from the results shown in Table 2, trial numbers 2 to 8 and trial numbers 13 to 1 satisfying the conditions specified in the present invention.
The steel sheet of No. 6 has a CAR of 0 to 2.8% and good HIC resistance.

On the other hand, the steel sheets of trial Nos. 9 to 12 in which the average Mn concentration in the plate thickness center portion or the maximum Mn concentration in the plate thickness center portion do not satisfy the conditions specified in the present invention have CARs of 4.4 to 4.
At 10.4%, the HIC resistance is poor. Further, in the steel sheet of trial No. 1 in which reduction was not applied at the time of manufacturing the slab, the maximum Mn concentration in the central portion of the sheet thickness satisfies the condition of the present invention, but the average Mn concentration in the central portion of the sheet thickness Since it is also high, the CAR is 18.3% and the HIC resistance is poor.

[0055]

[Table 1]

[Table 2]

The steel material of the present invention has a Mn content of 1.5%.
Even when it exceeds, it stably exhibits good HIC resistance. For this reason, high-strength steel materials, which will be in increasing demand in the future, can be supplied with inexpensive high-Mn steels.

[Brief description of drawings]

FIG. 1 is a schematic diagram showing a concentration distribution state of an alloy element (Mn) in a plate thickness center segregated portion of a steel material (steel sheet) manufactured by a conventional continuous casting slab.

FIG. 2 is a schematic view showing a concentration distribution state of an alloy element (Mn) in a plate thickness center segregated portion of a steel material (steel plate) according to the present invention.

─────────────────────────────────────────────────── ─── Continuation of front page (51) Int.Cl. ⁷ Identification code FI theme code (reference) C22C 38/58 C22C 38/58

Claims (5)

[Claims] 1. The average Mn concentration in the central portion of the plate thickness is the average Mn in steel.
A steel material having a hydrogen-induced cracking resistance that is lower than the concentration and has a maximum Mn concentration of 2.9% by mass or less in the central portion of the plate thickness. 2. The average Mn concentration in the central portion of the plate thickness is the average Mn in steel.
The steel material having excellent resistance to hydrogen-induced cracking according to claim 1, having a concentration of 0.95 times or less. 3. The chemical composition of steel in mass% is C: 0.01.
~ 0.1%, Si: 0.01-0.5%, Mn: 0.8
2%, P: 0.025% or less, S: 0.002% or less, Ca: 0.0005 to 0.005%, Ti: 0.0
05-0.05%, Nb: 0.005-0.1%, sol.
The steel material excellent in hydrogen-induced cracking resistance according to claim 1 or 2, comprising Al: 0.005 to 0.05% and N: 0.01% or less, and the balance being Fe and impurities. 4. In place of a part of Fe, in mass%, V: 0.
The steel material excellent in hydrogen-induced cracking resistance according to claim 3, containing 2% or less. 5. In place of a part of Fe, in mass%, Cu:
0.5% or less, Ni: 0.5% or less, Cr: 3% or less,
The steel material excellent in hydrogen-induced cracking resistance according to claim 3 or 4, containing at least one of Mo: 1.5% or less and B: 0.002% or less.