JPH10140250A - Manufacturing method of steel tube for high strength and high toughness air bag - Google Patents

Abstract

(57) [Summary] [PROBLEMS] To manufacture a steel pipe suitable for airbag parts requiring high dimensional accuracy, excellent workability and weldability, and high strength and high toughness. SOLUTION: C: 0.01% to 0.20%, Si:
0.50% or less, Mn: 0.30% to 2.00%, P:
0.020% or less, S: 0.020% or less, Al: 0.
After producing steel containing 10% or less, the balance being Fe and unavoidable impurities, the steel is quenched at 850 to 1000 ° C., and then cold-worked to a predetermined size or sintered after cold-working. By performing the masashi treatment, a steel pipe having high strength, high toughness, high dimensional accuracy, and excellent workability and weldability sufficient for an accumulator of an air bag is obtained.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a high-strength and high-toughness airbag for a steel pipe for an airbag which requires high dimensional accuracy, excellent workability, and high strength and high toughness of 590 N / mm ² or more. The present invention relates to a method for manufacturing a steel pipe.

[0002]

2. Description of the Related Art In recent years, the automobile industry has been actively introducing devices that pursue safety. Among them, before an occupant collides with a steering wheel, an instrument panel, or the like at the time of a collision, the occupant is required to carry out the same. An airbag system that deploys an airbag between the occupant with gas or the like and absorbs the kinetic energy of the occupant to reduce injuries has been developed and installed. Conventionally, a system using explosive chemicals has been adopted as an air bag system. However, in recent years, a system using an argon gas-filled steel pipe accumulator has been developed because of its high cost, environmental problems and recycling problems. The steel pipe used for accumulators such as argon gas always keeps 300 kgf / cm ² of inert gas and the like blown into the air bag at the time of collision, and then adds a small amount of gas at the time of collision to ignite the explosive, so that the gas is blown at once. Since it is ejected, stress is applied at a large strain rate in a very short time, unlike conventional structures such as pressure cylinders and line pipes, it has high strength, high toughness, high dimensional accuracy, workability, and weldability. Is required.

[0003] In the case of a steel pipe accumulator used for this purpose, the toughness is reduced due to the increase in strength by the conventional combination of cold drawing and stress relief annealing, and the above requirements cannot be satisfied. Further, mere quenching and tempering of a steel pipe has a problem that even if high strength, high toughness and high workability are obtained, a predetermined high dimensional accuracy cannot be obtained.

As another method, C: 0.15 to 0.15
0.30%, Si: 0.05 to 0.50%, Mn: 0.
30 to 1.00%, P: 0.040% or less, S: 0.0
A method in which an electric resistance welded tube containing 10% or less, the balance being Fe and unavoidable impurities is used as a material, and a bainite structure is formed by quenching and tempering, followed by cold drawing and stress relief annealing (Japanese Patent Laid-Open No. 4-191323); C: 0.15
0.40%, Si: 0.1 to 0.7%, Mn: 0.5 to
2.5%, Cr: 0.2-2.5%, Sol. Al:
Steel containing 0.01 to 0.05%, with the balance being Fe and unavoidable impurities, or C: 0.15 to 0.40
%, Si: 0.1 to 0.7%, Mn: 0.5 to 2.5
%, Cr: 0.2 to 2.5%, Sol. Al: 0.01
-0.05%, Mo: 0.05-1.0%, V: 0.
02-0.1%, Ni: 0.2-2.5%, Ti: 0.
02 to 0.10%, Nb: 0.02 to 0.10%, B:
Steel containing at least one of 0.0005 to 0.005%, the balance being Fe and unavoidable impurities is used as a material, hot rolled into a hot-rolled steel sheet, and after softening and annealing, formed into a tube and welded After cold-working the manufactured steel pipe so as to have a predetermined part shape, the steel pipe is heated at 850 to 1050 ° C. for 0.5 to 30 minutes and then air-cooled (Japanese Patent Laid-Open No. 5-3).
No. 02119) has been proposed.

[0005]

SUMMARY OF THE INVENTION The above-mentioned Japanese Patent Application Laid-Open No. 4-191 is disclosed.
Although the method disclosed in Japanese Patent No. 323 aims to improve the machinability by bainite organization, it is necessary to increase the amount of C in order to obtain a bainite structure by quenching, and C: 0.15 to 0.15. It needs to be as high as 0.30%. However, by increasing the amount of C in this way,
In addition, when it has a bainite structure, it generally has poor ductility and toughness, and is not suitable for applications such as pipe end drawing for accumulators for air bags, and has problems in weldability and the like.

The method disclosed in Japanese Patent Application Laid-Open No. 5-302119 is similar to the method disclosed in Japanese Patent Application Laid-Open No. 4-191323, and has a high C: 0.15 to 0.40%.
Generally, it has poor ductility and toughness, and is not suitable for uses such as an accumulator for an air bag, which is used for drawing a pipe end, and has problems in weldability and the like.

SUMMARY OF THE INVENTION An object of the present invention is to solve the above-mentioned drawbacks of the prior art, and to provide a workability suitable for airbag parts which require high dimensional accuracy, excellent workability and weldability, and high strength and high toughness. An object of the present invention is to provide a method for producing an excellent high-strength and toughness steel pipe.

[0008]

Means for Solving the Problems The present inventors have intensively studied and studied to achieve the above object. As a result, after the steel having a predetermined composition is formed, first, quenching or quenching and tempering are performed to impart toughness, then cold working is performed to obtain a predetermined dimension, and thereafter, heat treatment is not performed to obtain predetermined characteristics. In this case, it has been determined that a steel pipe having high dimensional accuracy, excellent workability and weldability, and high strength and high toughness can be obtained by performing annealing treatment.

The method for producing a steel pipe for a high-strength high-toughness air bag according to the first aspect of the present invention is characterized in that C: 0.05% or more and 0.15% or more.
%, Si: 0.50% or less, Mn: 0.30% or more
2.00%, P: 0.020% or less, S: 0.020%
Hereinafter, after producing steel containing 0.10% or less of Al and the balance consisting of Fe and unavoidable impurities, 850 to 100% is produced.
After quenching at 0 ° C., annealing is performed while cold working to a predetermined size or after cold working. As described above, by limiting the chemical components in the steel to the above component composition, it is possible to obtain sufficient strength, toughness, high workability, and weldability for an accumulator of an airbag. In addition, after the above steel pipe is made, 850 to 1000
After quenching at ℃, with cold working to the specified dimensions or by annealing after cold working, processing with high strength, high toughness and high dimensional accuracy suitable for the properties of the final purpose A steel pipe having excellent weldability and weldability can be obtained.

The method for producing a steel pipe for a high-strength, high-toughness air bag according to claim 2 of the present invention comprises the steps of: C: 0.05% or more and less than 0.15%; Si: 0.50% or less; 3
0% to 2.00%, P: 0.020% or less, S: 0.0
20% or less, Al: 0.10% or less, the balance being F
e and 850 after steel pipes made of unavoidable impurities
After quenching at 1000 ° C. and tempering at 450 ° C. or more and less than the Ac1 transformation point, annealing is performed while cold working to a predetermined dimension or after cold working. As described above, by limiting the chemical components in the steel to the above component composition, it is possible to obtain sufficient strength, toughness, high workability, and weldability for an accumulator of an airbag. In addition, after the above steel pipe is made, 850 to 100
After quenching at 0 ° C. and tempering at 450 ° C. or more and less than the Ac1 transformation point, by performing cold working to a predetermined size or performing annealing after cold working, the final purpose is obtained. A steel pipe having high strength, high toughness, high dimensional accuracy and excellent workability and weldability suitable for the characteristics can be obtained.

Further, the method for producing a steel pipe for a high-strength, high-toughness air bag according to claim 3 of the present invention is as follows: C: 0.05% or more and less than 0.15%; Si: 0.50% or less; 3
0% to 2.00%, P: 0.020% or less, S: 0.0
20% or less, Al: 0.10% or less, Mo: 0.
50% or less, V: 0.10% or less, Ni: 0.50% or less, Cr: 1.00% or less, Cu: 0.50% or less, T
i: 0.10% or less, Nb: 0.10% or less, B: 0.
After producing a steel containing at least one of 005% or less and the balance being Fe and inevitable impurities, 850 to 100%
After quenching at 0 ° C., annealing is performed while cold working to a predetermined size or after cold working. As described above, by limiting the chemical components in the steel to the above component composition, it is possible to obtain sufficient strength, toughness, high workability, and weldability for an accumulator of an airbag. In addition, after the above steel pipe is made, 850 to 1000
After quenching at ℃, with cold working to the specified dimensions or by annealing after cold working, processing with high strength, high toughness and high dimensional accuracy suitable for the properties of the final purpose A steel pipe having excellent weldability and weldability can be obtained.

Further, the method for producing a steel pipe for a high-strength and tough airbag according to claim 4 of the present invention is characterized in that: C: 0.05%
Not less than 0.15%, Si: 0.50% or less, Mn:
0.30% to 2.00%, P: 0.020% or less, S:
0.020% or less, Al: 0.10% or less, M
o: 0.50% or less, V: 0.10% or less, Ni: 0.
50% or less, Cr: 1.00% or less, Cu: 0.50%
Hereinafter, Ti: 0.10% or less, Nb: 0.10% or less,
B: After producing steel containing at least one of 0.005% or less and the balance being Fe and unavoidable impurities, 850%
After quenching at up to 1000 ° C. and tempering at 450 ° C. or more and less than the Ac1 transformation point, annealing is performed while cold working to a predetermined size or after cold working. As described above, by limiting the chemical components in the steel to the above component composition, it is possible to obtain sufficient strength, toughness, high workability, and weldability for an accumulator of an airbag. In addition, after the above steel pipe is made, 850-10
After quenching at 00 ° C. and tempering at 450 ° C. or more and less than the Ac1 transformation point, by performing cold working to a predetermined dimension or by performing annealing after cold working, A steel pipe having high strength, high toughness, high dimensional accuracy and excellent workability and weldability suitable for the characteristics can be obtained.

The method for producing a steel pipe for a high-strength, high-toughness airbag according to claim 5 of the present invention is characterized in that C: 0.01% to 0.1%.
20%, Si: 0.50% or less, Mn: 0.30% or more
2.00%, P: 0.020% or less, S: 0.020%
Hereinafter, after producing a steel containing Al: 0.1% or less and the balance being Fe and unavoidable impurities, 850 to 1000
After quenching at a temperature of ° C., annealing is performed while cold working to a predetermined size or after cold working. As described above, by limiting the chemical components in the steel to the above component composition, it is possible to obtain sufficient strength, toughness, high workability, and weldability for an accumulator of an airbag. In addition, after the above steel pipe is produced, 850-1000 ° C
After quenching at a specified temperature, by performing cold working to the specified dimensions or by performing annealing after cold working, workability with high strength, high toughness, high dimensional accuracy suitable for the final target properties And a steel pipe excellent in weldability can be obtained.

Further, the method for producing a steel pipe for a high-strength and tough airbag according to claim 6 of the present invention is characterized in that:
0.20%, Si: 0.50% or less, Mn: 0.30%
2.00%, P: 0.020% or less, S: 0.020
% Or less, Al: 0.10% or less, the balance being Fe and unavoidable impurities.
After quenching at 00 ° C. and tempering at 450 ° C. or more and less than the Ac1 transformation point, annealing is performed while cold working to a predetermined size or after cold working. As described above, by limiting the chemical components in the steel to the above component composition, it is possible to obtain sufficient strength, toughness, high workability, and weldability for an accumulator of an airbag. In addition, after the above steel pipe is produced, 850-1000 ° C
Quenching at 450 ° C. or higher and lower than the Ac1 transformation point, and then performing cold working to a predetermined size or annealing after cold working to achieve the final target characteristics A steel pipe with suitable high strength, high toughness, high dimensional accuracy, and excellent workability and weldability can be obtained.

Further, the method for producing a steel pipe for a high-strength, high-toughness airbag according to claim 7 of the present invention is characterized in that: C: 0.01%
0.20%, Si: 0.50% or less, Mn: 0.30
% To 2.00%, P: 0.020% or less, S: 0.02
0% or less, Al: 0.10% or less, Mo: 0.5
0% or less, V: 0.10% or less, Ni: 0.50% or less, Cr: 1.00% or less, Cu: 0.50% or less, T
i: 0.10% or less, Nb: 0.10% or less, B: 0.
After producing a steel containing at least one of 005% or less and the balance being Fe and inevitable impurities, 850 to 100%
After quenching at 0 ° C., annealing is performed while cold working to a predetermined size or after cold working. As described above, by limiting the chemical components in the steel to the above component composition, it is possible to obtain sufficient strength, toughness, high workability, and weldability for an accumulator of an airbag. In addition, after the above steel pipe is made, 850 to 1000
After quenching at ℃, cold-worked to the specified dimensions or by annealing after cold-working, processing with high strength, high toughness and high dimensional accuracy suitable for the final target properties A steel pipe having excellent weldability and weldability can be obtained.

The method for producing a steel pipe for a high-strength, high-toughness air bag according to claim 8 of the present invention is characterized in that C: 0.01% to 0.1%.
20%, Si: 0.50% or less, Mn: 0.30% or more
2.00%, P: 0.020% or less, S: 0.020%
Hereinafter, Al: 0.10% or less, Mo: 0.50%
V: 0.10% or less, Ni: 0.50% or less, C
r: 1.00% or less, Cu: 0.50% or less, Ti:
0.10% or less, Nb: 0.10% or less, B: 0.00
After producing a steel containing at least one of 5% or less, and the balance being Fe and unavoidable impurities, 850 to 1000 ° C.
After tempering at 450 ° C. or more and less than the Ac1 transformation point, annealing is performed with or without cold working to a predetermined size.
As described above, by limiting the chemical components in the steel to the above component composition, it is possible to obtain sufficient strength, toughness, high workability, and weldability for an accumulator of an airbag. Further, after the steel is made into a tube, the steel is quenched at 850 to 1000 ° C., tempered at 450 ° C. or higher and lower than the Ac1 transformation point, and then cold-worked to a predetermined size or quenched after cold working. By performing the annealing treatment, it is possible to obtain a steel pipe having high strength, high toughness, high dimensional accuracy, and excellent workability and weldability, which is suitable for the properties of the final purpose.

[0017]

DESCRIPTION OF THE PREFERRED EMBODIMENTS First, the reasons for limiting the chemical components of the steel used in the present invention are as follows. C is an element added to obtain the necessary strength of steel at low cost.
If it is less than 0.01%, sufficient strength cannot be obtained.
If it exceeds 20%, workability and weldability are deteriorated and toughness is reduced. Therefore, the content is set to 0.01 to 0.20%. A particularly preferable range is 0.05% or more and less than 0.15%. .

Si is an element that inhibits the cold workability of steel. If the content exceeds 0.50%, the workability deteriorates.
50% or less.

Mn is an effective element for improving the strength and toughness of steel. However, if it is less than 0.30%, sufficient strength and toughness cannot be obtained, and if it exceeds 2.00%, the weldability becomes poor. Due to deterioration, the content was set to 0.30 to 2.00%.

Since P causes a decrease in toughness due to grain boundary segregation, the content of P is set to 0.020% or less. S is combined with Mn in steel to form inclusions due to MnS, thereby deteriorating workability and decreasing toughness.

Al has an element effective for improving the workability, but if the content exceeds 0.10%, the effect is reduced. Therefore, the content is set to 0.10% or less.

By limiting the above chemical components in steel, it is possible to obtain sufficient strength, toughness, high workability and weldability for an accumulator of an air bag. It is effective to further add Mo, V, Ni, Cr, Cu, Ti, Nb, and B to the components. The reasons for limiting the contents of these additional components are as follows.

Mo has the effect of increasing the strength by solid solution strengthening and improving the quenching properties. However, if it exceeds 0.50%, the welded part is hardened and the toughness is reduced, so that Mo is increased by 0.50%.
% Or less.

V has the effect of forming precipitates and improving the strength, but if it exceeds 0.10%, the toughness of the welded portion is reduced, so V is set to 0.10% or less.

Ni is an element effective for improving hardenability and toughness. However, even if it exceeds 0.50%, it has an effect, but it is expensive.

Cr is an effective element for improving the strength and corrosion resistance of steel. However, if it exceeds 1.00%, the workability and the toughness of the welded portion are reduced.

Although Cu is an effective element for improving the corrosion resistance of steel, if it exceeds 0.50%, the hot workability is deteriorated.

Ti is effective in improving the toughness by making the structure finer, but when it exceeds 0.10%, the toughness is adversely deteriorated. Therefore, the content of Ti is set to 0.10% or less.

Like Nb, Nb is effective in improving the toughness by refining the structure. However, when Nb exceeds 0.10%, on the contrary, the toughness is deteriorated.

B is an element effective for improving the hardenability, but if it exceeds 0.005%, the toughness is reduced.

In the present invention, a pipe is made from a steel material whose chemical components have been adjusted as described above. As the pipe making method, there are a method of performing electric resistance welding using a hot-rolled steel strip and a seamless pipe making method of hot forming using a billet, and any method may be used.

The steel pipe thus manufactured is first subjected to quenching or quenching and tempering to impart toughness. If the temperature during quenching is lower than 850 ° C., uniform austenite grains cannot be obtained, and if it exceeds 1000 ° C., the crystal grains become coarse and the toughness is reduced. As the tempering temperature, the temperature at which the strength, workability, and toughness are the best may be selected. However, when the temperature becomes equal to or higher than the Ac1 transformation point, the transformation is started, and the desired target strength and toughness cannot be obtained. Although the temperature is 450 ° C. or higher and lower than the Ac1 transformation point, a preferable range is 500 to 650 ° C.

The cold working after quenching or quenching and tempering may be carried out under the condition that a predetermined dimensional accuracy can be obtained, and it is not particularly necessary to define the working degree. Annealing after cold working is performed to give the target strength, workability, and toughness, but if higher strength and higher dimensional accuracy are more important than workability and toughness, cold working Leave it alone. The annealing treatment is applied when high strength and high toughness are required even if the strength is slightly reduced. In any of the above processes, desired characteristics can be obtained by performing a heat treatment suitable for the characteristics of the final target.

[0034]

EXAMPLE Using a billet of the steel of the present invention having the chemical components shown in Table 1 and a comparative steel having the chemical components shown in Table 2, piercing and rolling were performed by the Mannesmann-mandrel mill method.
Finished with a reducer to an outer diameter of 76.2 mm and a wall thickness of 4.0 mm. Then, after quenching (Q) at 800 ° C. to 1050 ° C., the quenching is continued or 500 ° C.
The seamless steel pipe that has been tempered (T) at 50 ° C. for 30 minutes is
Cold drawing, outer diameter 65.0mm, wall thickness 3.2mm
Or cold working or annealing at a temperature of 580 ° C. to evaluate various properties. The results are shown in Tables 3 and 4.

The characteristics were evaluated for strength, toughness, and workability. Regarding the strength, the specified JIS Z2201 metal material tensile test piece was used as specified in JIS Z2201.
A tensile test was performed according to the metal material tensile test method of Z2241. As for the toughness, as shown in FIG. 1, the seamless steel pipe 1 was cut in half as shown by a dashed line, and a half test piece 2 having a length of 10 mm was collected and placed on the table 3 of the drop test apparatus shown in FIG. The half-specimen 2 was placed on the table, and a weight 4 having a weight of 5 kg was dropped from a position of 2000 mm from the upper surface of the table 3 to check for cracks. The drop weight test was repeated 10 times at −40 ° C. and evaluated by the crack rate. Workability was evaluated in terms of flatness. As shown in FIG. 3, the flatness of the V-block (60 mm
°) using the pressing tools 5 and 5 to flatten the seamless steel pipe 1 until it comes into close contact, and evaluate the presence or absence of cracks in the shoulder 6 of the largest flat part. Existence was evaluated as ×.

[0036]

[Table 1]

[0037]

[Table 2]

[0038]

[Table 3]

[0039]

[Table 4]

As shown in Tables 1 and 3, the steel No. 1 to 1
8 using the steel of the present invention. The inventive examples 1 to 22 have a tensile strength of 5 in all components and processes.
High strength of 90 N / mm ² or more, and 0% cracking rate in the drop test, no cracking of the shoulder after flattening,
It had good workability.

On the other hand, as shown in Tables 2 and 4, steel No. Comparative steels Nos. 19 to 26 and steel Nos. Test No. 18 using No. 18 Comparative Examples 23 to 34 are test Nos. 23, 2
In Test Nos. 6 and 31, the tensile strength was 590 N / mm ² or less and the strength was insufficient. 24, 27-30, 32, 34
Has a cracking rate of 10% or more in a drop weight test, and a crack at the shoulder portion after flattening occurs, resulting in insufficient toughness and workability. 25 and 33 have insufficient toughness. In the present embodiment, an example of a seamless steel pipe is shown, but it goes without saying that the same characteristics can be obtained by using a welded steel pipe.

[0042]

According to the method for producing a steel pipe for a high-strength, high-toughness air bag of the present invention, steel having a chemical composition adjusted is made, quenched at 850 to 1000 ° C., and then cold-formed to a predetermined size. High dimensional accuracy, excellent workability and weldability, and high strength, high toughness steel pipe suitable for applications such as accumulators for airbags by performing annealing after cold working or after cold working. Can be obtained.

[Brief description of the drawings]

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is an explanatory view of a drop weight test piece in an embodiment, and FIG.
The figure is a perspective view of the half-split method, and the figure (b) is a perspective view of a drop weight test piece.

FIG. 2 is a schematic explanatory view for explaining a drop weight test method in an example.

FIG. 3 is a schematic explanatory view for explaining an adhesion flatness test method in an example.

[Explanation of symbols]

 Reference Signs List 1 seamless steel pipe 2 half test piece 3 table 4 weight 5 pressing tool 6 shoulder

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁶ Identification code FI C22C 38/06 C22C 38/06 38/58 38/58

Claims (8)

[Claims] 1. C: 0.05% or more and less than 0.15%, S
i: 0.50% or less, Mn: 0.30% to 2.00%,
P: 0.020% or less, S: 0.020% or less, Al:
After producing a steel containing 0.10% or less, the balance being Fe and unavoidable impurities, after quenching at 850 to 1000 ° C., the steel is subjected to cold working to a predetermined size or after cold working. A method for producing a steel pipe for a high-strength, high-toughness airbag, which comprises performing an annealing treatment. 2. C: 0.05% or more and less than 0.15%, S
i: 0.50% or less, Mn: 0.30% to 2.00%,
P: 0.020% or less, S: 0.020% or less, Al:
After producing a steel containing 0.10% or less, the balance being Fe and unavoidable impurities, after quenching at 850 to 1000 ° C and tempering at 450 ° C or more and less than the Ac1 transformation point, predetermined dimensions are obtained. A method for producing a steel pipe for a high-strength and tough airbag, wherein the steel sheet is subjected to an annealing treatment with or without cold working. 3. C: 0.05% or more and less than 0.15%, S
i: 0.50% or less, Mn: 0.30% to 2.00%,
P: 0.020% or less, S: 0.020% or less, Al:
0.10% or less, Mo: 0.50% or less, V:
0.10% or less, Ni: 0.50% or less, Cr: 1.0
0% or less, Cu: 0.50% or less, Ti: 0.10% or less, Nb: 0.10% or less, B: 0.005% or less, the balance being Fe and inevitable High strength, high toughness characterized by subjecting steel made of impurities to quenching at 850-1000 ° C. after quenching, and then subjecting to cold working to predetermined dimensions or annealing after cold working. Manufacturing method of steel pipe for airbag. 4. C: 0.05% or more and less than 0.15%, S
i: 0.50% or less, Mn: 0.30% to 2.00%,
P: 0.020% or less, S: 0.020% or less, Al:
0.10% or less, Mo: 0.50% or less, V:
0.10% or less, Ni: 0.50% or less, Cr: 1.0
0% or less, Cu: 0.50% or less, Ti: 0.10% or less, Nb: 0.10% or less, B: 0.005% or less, the balance being Fe and inevitable After the pipe made of the steel made of impurities, quenching at 850 to 1000 ° C.,
After tempering at 450 ° C. or higher and lower than the Ac1 transformation point, a high-strength high-toughness airbag is characterized in that a predetermined size is subjected to cold working or is subjected to annealing after cold working. Manufacturing method of steel pipe. 5. C: 0.01% to 0.20%, Si:
0.50% or less, Mn: 0.30% to 2.00%, P:
0.020% or less, S: 0.020% or less, Al: 0.
After producing steel containing 10% or less, the balance being Fe and unavoidable impurities, the steel is quenched at 850 to 1000 ° C., and then cold-worked to a predetermined size or sintered after cold-working. A method for producing a steel pipe for a high-strength, high-toughness airbag, which is characterized by performing a masashi treatment. 6. C: 0.01% to 0.20%, Si:
0.50% or less, Mn: 0.30% to 2.00%, P:
0.020% or less, S: 0.020% or less, Al: 0.
After producing a steel containing 10% or less, the balance being Fe and unavoidable impurities, quenching at 850 to 1000 ° C,
After tempering at 450 ° C. or higher and lower than the Ac1 transformation point, a high-strength high-toughness air bag characterized by being subjected to an annealing treatment with or without cold working to a predetermined size. Manufacturing method of steel pipe. 7. C: 0.01% to 0.20%, Si:
0.50% or less, Mn: 0.30% to 2.00%, P:
0.020% or less, S: 0.020% or less, Al: 0.
Including 10% or less, Mo: 0.50% or less, V: 0.1
0% or less, Ni: 0.50% or less, Cr: 1.00% or less, Cu: 0.50% or less, Ti: 0.10% or less, N
b: 0.10% or less, B: 0.005% or less, and after quenching at 850-1000 ° C. after pipe-forming steel containing at least one of Fe and inevitable impurities,
A method for producing a steel tube for a high-strength and tough airbag, wherein an annealing process is performed while cold working is performed to a predetermined size or after cold working. 8. C: 0.01% to 0.20%, Si:
0.50% or less, Mn: 0.30% to 2.00%, P:
0.020% or less, S: 0.020% or less, Al: 0.
Including 10% or less, Mo: 0.50% or less, V: 0.1
0% or less, Ni: 0.50% or less, Cr: 1.00% or less, Cu: 0.50% or less, Ti: 0.10% or less, N
b: 0.10% or less, B: 0.005% or less, the steel containing at least one of Fe and unavoidable impurities, and then quenching at 850 to 1000 ° C.
A steel pipe for a high-strength high-toughness airbag, characterized in that after tempering at a temperature of at least C1 and lower than the Ac1 transformation point, annealing is performed while cold working to a predetermined size or after cold working. Manufacturing method.