CN1902330A

CN1902330A - Low carbon alloy steel tube having ultra high strength and excellent toughness at low temperature and method of manufacturing the same

Info

Publication number: CN1902330A
Application number: CN 200480028146
Authority: CN
Inventors: 埃德高多·奥斯卡·洛佩斯; 爱德华多·阿尔特舒勒
Original assignee: Tenaris Connections AG
Current assignee: Tenaris Connections BV
Priority date: 2003-10-10
Filing date: 2004-10-11
Publication date: 2007-01-24
Anticipated expiration: 2024-10-11
Also published as: CN100460527C; AR046543A1

Abstract

A low carbon alloy steel tube and a method of manufacturing the same, in which the steel tube consists essentially of, by weight: about 0.06% to about 0.18% carbon; about 0.5% to about 1.5% manganese; about 0.1% to about 0.5% silicon; up to about 0.015% sulfur; up to about 0.025% phosphorous; up to about 0.50% nickel; about 0.1% to about 1.0% chromium; about 0.1% to about 1.0% molybdenum; about 0.01% to about 0.10% vanadium; about 0.01% to about 0.10% titanium; about 0.05% to about 0.35% copper; about 0.010% to about 0.050% aluminum; up to about 0.05% niobium; up to about 0.15% residual elements; and the balance iron and incidental impurities. The steel has a tensile strength of at least about 145 ksi and exhibits ductile behavior at temperatures as low as -60 DEG C.

Description

Have superstrength and fabulous flexible low-carbon alloy steel pipe and manufacture method thereof at low temperatures

Related application

The application requires the right of priority of the non-temporary patent application of the U.S. number of the U.S. Provisional Patent Application number application on October 5th, 60/509806 and 2004 of on October 10th, 2003 application.

Technical field

The present invention relates to a kind ofly have superstrength and fabulous flexible low-carbon alloy steel pipe at low temperatures, and the manufacture method of this steel pipe.Described steel pipe is suitable for making the container parts that is used for the vehicle restraint system parts, and an example is exactly the aerator of automotive airbag.

Background technology

The airbag inflator that is used for vehicles occupant restraint system need satisfy strict 26S Proteasome Structure and Function standard.Therefore, the essential process that adopts strictness in manufacturing process.Though test in place shows the industrial 26S Proteasome Structure and Function standard in the past that satisfied, need to improve and/or new performance to satisfy the needs of development, though it is also very important constantly to reduce manufacturing cost simultaneously.

In current many vehicles, air bag or supplemental restraint system all are important security features.In the past, gas-bag system adopts volatile pharmaceutical chemicals, but its costliness, and because environment and recovery problem in recent years, have been developed a kind of aerator of novel type, its utilization is full of the pressure reservoir of nitrogen or class/make like the steel pipe of thing, and such use is increasing.

Above-mentioned pressure reservoir is a kind of container, and normal time, this pressure reservoir was preserved highly compressed gas or analogue, exploded into air bag in one or more blast stage when car collision.Correspondingly, in the extremely short time period, be subjected to the stress of high strain rate as the steel pipe of this pressure reservoir.Therefore, compare with simple structure such as common pressurized cylinder, above-mentioned steel pipe needs high dimension precision, workability and weldability, and it must also have high strength, toughness and fabulous explosion-proof performance.It is important that dimensional precision charges into air bag for the gas that guarantees very accurate body warp.

Cold formability is extremely important for the tubular member of making pressure reservoir, because they form finished steel after the seamless tube manufacturing.Different shapes depends on the container structure that obtains by cold shaping.Key is the pressurized vessel that obtains not have crack and surface imperfection after cold shaping.In addition, also be vital even after cold shaping, have extraordinary toughness at low temperatures.

The steel of having developed has extraordinary weldability, need not preheat or weld postheat treatment before welding.In order to obtain required weldability, it is about 0.63% that carbon equivalent should be lower than, as shown in the formula qualification,

Ceq＝％C+％Mn/6+(％Cr+％Mo+％V)/5+(％Ni+％Cu)/15

In the preferred embodiment of the invention, as defined above carbon equivalent should be lower than about 0.63% so that guarantee weldability better.

For the process gas container, cold-drawn pipe prepared in accordance with the present invention is cut off on length, utilizes the cold formation of different known technology (as wrinkling, as to swage etc.) so that obtain required shape then.Alternately, can adopt welded tube.Subsequently, in order to produce pressure reservoir, utilize suitable technology blind plate and scatterer to be welded to each end of container as the pressure welding that rubs, gas tungsten arc welding or Laser Welding etc.These welding are very strict, need suitable labor force, test in some cases to guarantee the weld integrity of whole pressurized vessel and airbag deployment (deployment).Having observed these welding can break or damage, and jeopardizes the integrity of pressure reservoir and the work of possibility air bag.

The test aerator is to guarantee that it can guarantee structural integrity in the air bag use.One of them test is exactly so-called bursting test.This is a kind of destructive test, when jar suffers to use than its normal running in test, i.e. and the remarkable high interior pressure of airbag deployment.In this test, the interior straightening that aerator is raise is to breaking.

From these tests, look back the result and the research trial jar sample of bursting test, find that fracture takes place in two kinds of different modes: ductile rupture and brittle rupture, dual mode associating sometimes.Observed in ductile rupture, the projection (bubble is showed as breaking) that takes place to disconnect is the fracture of turning up of example.Fracture surface tilts near 45 degree with respect to the outside surface of pipe, is positioned at the target area.On the other hand, in brittle rupture, show non-significant longitudinal crack, in this symbol material the brittle zone is arranged along the aerator length direction.In the case, surface of fracture is normal for tube outer surface.These two kinds of fracture modes have distinguishing surface when observing under scanning electronic microscope, and indenture is the feature of ductile rupture, and the crack is the brittle rupture symbol simultaneously.

Sometimes, can observe the associating of these two kinds of fracture modes, brittle crack is expanded from the toughness burst region.Because total system comprises airbag inflator, can in the vehicles of very different weather operations, use, key is that material shows ductility in wide temperature range, and is warm from being as cold as very much.

Summary of the invention

The present invention relates to a kind of be suitable for having superstrength under the low temperature (minimum UTS 145ksi) and very high parting pressure.In addition, described steel has fabulous toughness at low temperatures, and-60 ℃ guarantee ductility, and promptly tough-crisp transition temperature (DBTT) is lower than-60 ℃, even may reach-100 ℃.The invention still further relates to the manufacturing process of this steel pipe.

Material of the present invention is designed for the container parts of preparation vehicle restraint system parts, for example automotive airbag aerator.

Preferred forms

Though the embodiment that the present invention allows has various forms, should be appreciated that hereinafter with the preferred embodiment of describing disclosed be a kind of example of the present invention, rather than the embodiment shown in the present invention is defined as.

The present invention relates to a kind of steel pipe that is used to place the gasbag pressure container.More specifically, the present invention relates to a kind of low-carbon (LC) superstrength steel grade that is used for seamless pressurized vessel, it guarantees ductility at-60 ℃, and promptly tough-crisp transition temperature (DBTT) is lower than-60 ℃.

More specifically, the present invention relates to a kind of chemical ingredients and a kind of manufacturing process that is used to make the weldless steel tube of air bag.

A kind of synoptic diagram of manufacture method of the possible seamless low-carbon (LC) ultrahigh-strength steel of production is as follows:

1. steel-making

2. cast steel

3.Tue hot rolling

4. hot rolling depression (hollow) finishing procedure

5. cold drawn

6. thermal treatment

7. cold-drawn pipe finishing procedure

A main purpose of process for making is by removing carbon elimination, silicon, sulphur, phosphorus and the concise iron of manganese.Especially, because the mechanical property of sulphur and phosphorus infringement material, they are deleterious to steel.Before or after based process, utilize the specific purification step of ladle metallurgy, so that in the steel making working procedure on basis, can accelerate to handle.

Process for making carries out under extremely pure condition to obtain low-down sulphur and phosphorus content, and it is again the key that obtains required superstrength product.Correspondingly, the target of impurity level is 2 or lower-thin series and 1 or lower-thick series, adopts the substandard criterion of ASTM E45-Worst Field Method (method A).In a preferred embodiment of the invention, the maximum little foreign matter content according to above-mentioned canonical measure should be:

Dopant type	Thin	Thick
Dopant type	Thin	Thick	A	0.5	0
B	1.5	1.0	A	0.5	0
B	1.5	1.0	C	0	0
D	1.5	0.5	C	0	0

In addition, extremely pure conditions permit obtains oversized dimensions impurity and is of a size of 30 microns or littler.The total oxygen level of the limit of these foreign matter contents that obtained is 20ppm.

In secondary metallurgy, extremely pure condition is by being blown into rare gas element to force the floating enforcement of impurity and impurity in ladle furnace.The fluid slag product can absorb impurity and impurity, and contaminant size and shape change by add calcification silicon in the liquid steel, produce the high-quality steel of low impurity content.

Chemical ingredients is as follows in the steel that is obtained, and " % " refers to " mass percent " under the various situations:

Carbon (C)

Carbon is a kind of element of raising hardness of steel of cheapness, if but its content is lower than 0.06%, just be difficult to obtain required intensity.On the other hand, if the carbon content in the steel is higher than 0.18%, then cold-workability, weldability and toughness reduce.Therefore, the carbon content scope is 0.006%-0.18%.Preferred carbon content scope is 0.07%-0.12%, even preferred scope is 0.08%-0.11%.

Manganese (Mn)

Manganese is a kind of element of effective raising steel hardness, so it improves intensity and toughness.If its content is lower than 0.5%, just be difficult to obtain required intensity, yet it surpasses 1.5% energy band structure and becomes obviously, and toughness reduction.Therefore, the content of manganese is 0.5%-1.5%.Yet the scope of preferred manganese is 1.00%-1.40%, and preferred scope is 1.03%-1.18%.

Silicon (Si)

Silicon is a kind of deoxidation effect that has in process for making, can also improve the element of the intensity of steel.If silicone content is lower than 0.10%, steel is easy to oxidation, and on the other hand, if its content is higher than 0.50%, then toughness and workability all reduce.Therefore, silicone content is 0.1%-0.5%.The scope of preferred silicon is 0.15%-0.35%.

Sulphur (S)

Sulphur is a kind of element that causes steel toughness to reduce.Therefore, the maximum level of sulphur is limited to 0.015%.Preferred maximum is 0.010%, and preferred maximum value is 0.003%.

Phosphorus (P)

Phosphorus is a kind of element that causes steel toughness to reduce.Therefore, the maximum level of phosphorus is limited to 0.025%.Preferred maximum is 0.015%, and more preferably maximum value is 0.012%.

Nickel (Ni)

Nickel is to improve hardness of steel and flexible element, but very expensive, so the maximum level of nickel is limited to 0.50%.Preferred maximum is 0.20%, and preferred maximum value is 0.10%.

Chromium (Gr)

Chromium is a kind ofly can effectively improve hardness of steel, toughness and corrosion proof element.If its content is lower than 0.10%, be difficult to obtain required intensity, yet if it surpasses 1.0%, then the toughness of welding zone reduces significantly.Therefore, the content of chromium is 0.1%-1.0%.Yet the scope of preferred chromium is 0.55%-0.80%, and preferred scope is 0.63%-0.73%.

Molybdenum (Mo)

Molybdenum is a kind of element of effective raising hardness of steel, and helps to postpone softening in tempering.If its content is lower than 0.10%, be difficult to obtain the intensity of welding zone, yet if it surpasses 1.0%, then the toughness of welding zone reduces significantly.Therefore, the content of molybdenum is 0.1%-1.0%.Yet this iron alloy is expensive, need reduce maximum level forcibly.Therefore, the scope of preferred molybdenum is 0.30%-0.50%, and preferred scope is 0.40%-0.45%.

Vanadium (V)

Vanadium is a kind of element that can effectively improve hardness of steel, even add on a small quantity, and allows to postpone softening in tempering.The optimum content of finding vanadium is 0.01%-0.10%.Yet this iron alloy is expensive, need reduce maximum level forcibly.Therefore, the scope of preferred vanadium is 0.01%-0.07%, and preferred scope is 0.03-0.05%.

Titanium (Ti)

Titanium is-kind can effectively improve the element of hardness of steel, even add a small amount of.The optimum content of finding titanium is 0.01%-0.10%.Yet this iron alloy is expensive, need reduce maximum level forcibly.Therefore, the scope of preferred vanadium is 0.01%-0.05%, and preferred scope is 0.025-0.035%.

Copper (Cu)

This element improves the solidity to corrosion of pipe, so the content range of copper is 0.05%-0.35%, and preferred range is 0.15%-0.30%.

Aluminium (Al)

This element adds in process for making to reduce foreign matter content and concise crystalline grain of steel.The content of preferred aluminium is 0.010%-0.050%.

The preferable range of the element of not listing above other is as follows:

Element wt

Niobium 0.05% maximum

Tin 0.05% maximum

Antimony 0.05% maximum

Plumbous 0.05% maximum

Arsenic 0.05% maximum

The residual element that are used for producing the single jar of steel in pipe or chamber should be:

Sn+Sb+Pb+As≤0.05% maximum

S+P≤0.025

Next step is a cast steel, can be by the solid-state steel bar of punching or spreading formation weldless steel tube to produce.Cast the solid billet that has the homogeneous diameter along the steel axle at steel workshop steel.

The solid cylinder steel bar of superelevation Clean Steel is heated to about 1200 ℃-1300 ℃, and carries out steel rolling process at this point.Preferably, steel bar is heated to 1250 ℃, then by the loud, high-pitched sound rolling mill.Steel bar is preferably utilized known Manessmann technology by punching, and external diameter and wall thickness reduce considerably in course of hot rolling subsequently, and length increases considerably simultaneously.For example, the steel bar of 148 mm outer diameter is rolled into the hot-rolled tube of 48.3 millimeters of external diameters, 3.25 millimeters of wall thickness.

As the measurement of solid-state section area and hot-rolled tube section area, section area is reduced to and obtains concise microstructure is important, is essential for obtaining required mechanical property.Therefore, minimum section area was reduced to 15: 1, and preferred and most preferred section area minimizing was respectively 20: 1 and 25: 1.

Seamless hot-finished tube cool to room temperature with the superelevation Clean Steel made thus.The seamless hot-finished tube of the superelevation Clean Steel of Zhi Zaoing is at the pipe circumference with radially all have a wall thickness near homogeneous along tubular axis thus.

After this, through the hot rolled pipe by different concise steps, for example length direction is cut into the 2-4 piece, and if desired, terminal cropped, aligning on known rotating and straightening equipment, and carry out nondestructively measuring by one or more different known technologies (for example electromagnetism is measured or ultrasound is measured).

After this, the surface of each hot rolling plumber block is cold drawn suitably arrangement.Described arrangement is included in acidleach in the acid solution, coats suitable lubricant film, zinc phosphate and stearic acid (estearathe) sodium combination as is known, perhaps active oil.After the surface dressing, weldless steel tube is by cold drawn, by diameter less than by the outside die drawing weldless steel tube of the external diameter of trombone slide.In most cases, the internal surface of described pipe is also supported by the interior core that an end is anchored on the ear of maize, so that described core close described mould in the process of drawing.This pulling process does not need described pipe is heated to more than the room temperature in advance.

Described seamless tube is once cold drawn at least, all reduces the external diameter and the wall thickness of pipe at every turn.The cold-drawn steel pipe of manufacturing has along tubular axis to the external diameter of homogeneous with at the pipe circumference with radially all have a wall thickness near homogeneous along tubular axis.Described cold-drawn pipe preferably has the external diameter of 10-70 millimeter, the wall thickness of preferred 1-4 millimeter.

After this, the thermal treatment in the austenitizing stove of described cold-drawn pipe, treatment temp is being higher than austenitizing temperature or Ac3 (for specific chemical property disclosed herein, being about 880 ℃) at least, but preferably is higher than 920 ℃ and be lower than 1050 ℃.The purpose that adopts this maximum austenitizing temperature is for fear of grain coarsening.This technology can be carried out in Fuel Furnace or conduction type furnace, but the preferred latter.Transition in stove (transit) time depends on the kind of using stove consumingly.Have been found that as adopting conduction type furnace more easily to obtain the required great surface quality of the application.This is because the characteristic of induction process wherein relates to very short transit time, has prevented the generation of oxidation.Preferably, the austenitizing heating rate is at least about 100 ℃ of per seconds, but at least 200 ℃ of per seconds more preferably.High heating rate and its result, very Duan heat-up time, extraordinary crystal grain microstructure is extremely important for obtaining, on the contrary it guarantees required mechanical property.

In addition, suitable stacking factor is defined as the ratio of the circumferential area that the circumferential area of circumferential area that the external diameter by described pipe limits and conduction type furnace coil pipe internal diameter limits, and is important for the required high heating rate of acquisition.Minimum stacking factor is about 0.16, and preferred minimum stacking factor is about 0.36.

At the outlet area of stove or near outlet area, described pipe extinguishes by suitable quench fluid.Quench fluid preferably water or water base quenching solution.Described pipe temperature drops to room temperature rapidly, preferably at least about 100 ℃ of per seconds, more preferably at least about 200 ℃ of per seconds.The high rate of cooling of this limit is crucial for obtaining microstructure conversion completely.

Described steel pipe is being lower than under the temperature of Ac1 under suitable temperature and tempering in cycling time.Preferably, tempering temperature is between 400-600 ℃, more preferably between 450-550 ℃.Soaking time answers sufficiently long guaranteeing extraordinary temperature homogeneity, if but oversize, then can not get required mechanical property.Therefore, the soaking time of employing is between 2-30 minute, preferably between 4-20 minute.The temperature adjustment process is preferably carried out under the reduction of protectiveness or neutral atmosphere, to avoid described pipe decarburization and oxidation.

The superstrength steel pipe of manufacturing carries out nondestructive mensuration by different concise steps at known rotating and straightening equipment aligning with by one or more known technology.Preferably, for this application pipe, should not only measure by known ultrasound technology but also by electromagnetic technique.

Tubing after the thermal treatment can chemical treatment to obtain required outward appearance and low-down surfaceness.For example, described pipe can be in sulfuric acid and hydrochloric acid acid, utilize zinc phosphate phosphatization and petroleum based oil or mineral oil to refuel.The steel pipe that obtains by described method should have following mechanical property so that reach order of the present invention:

The about 125ksi of yield strength (862MPa) is minimum

More preferably 135ksi (930MPa) is minimum

The about 145ksi of tensile strength (1000MPa) is minimum

Extend about 9% minimum

The about 40HRC maximum of hardness

More preferably 37HRC maximum

Yield strength, tensile strength, elongation and hardness test should be carried out according to the step described in ASTM E8 and the ASTM A370.For tensile strength, preferred full-scale sample is used to evaluate and test whole tubular section.

Squeezing test will meet 49 CFR, 178.65 joints, the requirement of standard DOT 39.Therefore, tube section should not break under 60 degree angle V-arrangement processing are flattened, until 6 thickness of pipe of opposite distance.The steel of manufacturing can satisfy this test comprehensively.

Well balanced in order to obtain between intensity and toughness, the austenite grain size of existing (being called the former sometimes) preferably should be 7 or thinner, and more preferably 9 or thinner, according to ASTM E-112 canonical measure.Can reach this is because the extremely short heating period in the austenitization.

The steel pipe that is obtained by described method should have described performance so that satisfy needs of the present invention.

The needs of industry constantly reduce required toughness value.The present invention has good surface appearance, has, and for example the surface smoothness of processing back internal surface of pipe and outside surface is maximum 3.2 microns.This requirement is by cold drawn, short austenitizing time, reduction or neutral atmosphere temperature adjustment, and the sufficient surface chemistry arrangement in the different step reaches in technology.

Should carry out the hydraulic pressure bursting test by the end in sealed tube cross section, for example by managing terminal Welding flat steel plate.300 millimeter tube cross sections keep not constraint down so that expand whole hoop stresses.The tube section pressurization is undertaken by pump oil, water-alcohol or their mixture.

Required parting pressure depends on the size of pipe.Through bursting test, the ultrahigh-strength steel seamless tube has the ductility of assurance under-60 ℃.The test of carrying out on the sample of producing shows that this kind steel pipe has the ductility of assurance under-60 ℃, and tough-crisp transition temperature is lower than-60 ℃.

The inventor finds that a kind of further representational validation test is bursting test, can carry out under room temperature or low temperature, replaces charpy impact test (according to ASTM E23).This is because therefore relative thick and little this fact of external diameter of thin-walled of these products that adopts is not laterally having the ASTM sample of standard to process for charpy impact test.In addition, impact probe, have to use flattening deformation for the curved tube probe in order to obtain this undersized Xia Shi.This mechanical property for steel has realizable effect, particularly shock strength.Therefore, in this process, do not obtain representational shock test.

Claims

1, a kind of low-carbon alloy steel pipe is mainly composed of the following components, calculates by weight: the carbon of about 0.06%-0.18%; The manganese of about 0.5%-1.5%; The silicon of about 0.1%-0.5%; Be up to about 0.015% sulphur; Be up to about 0.025% phosphorus; Be up to about 0.50% nickel; The chromium of about 0.1%-1.0%; The molybdenum of about 0.1%-1.0%; The vanadium of about 0.01%-0.1%; The titanium of about 0.01%-0.1%; The copper of about 0.05%-0.35%; The aluminium of about 0.010%-0.050%; Be up to about 0.05% niobium; Be up to about 0.15% residual element; And the iron of equal amount and inevitable impurity, wherein steel pipe has at least about the tensile strength of 145ksi and is lower than tough-crisp transition temperature of-60 ℃.

2, according to the low-carbon alloy steel of claim 1, wherein steel pipe is mainly composed of the following components, calculates by weight: the carbon of about 0.07%-0.12%; The manganese of about 1.00%-1.40%; The silicon of about 0.15%-0.35%; Be up to about 0.010% sulphur; Be up to about 0.015% phosphorus; Be up to about 0.20% nickel; The chromium of about 0.55%-0.80%; The molybdenum of about 0.30%-0.50%; The vanadium of about 0.01%-0.07%; The titanium of about 0.01%-0.05%; The copper of about 0.15%-0.30%; The aluminium of about 0.010%-0.050%; Be up to about 0.05% niobium; Be up to about 0.15% residual element; And the iron of equal amount and inevitable impurity.

3, according to the low-carbon alloy steel of claim 1, wherein steel pipe is mainly composed of the following components, calculates by weight: the carbon of about 0.08%-0.11%; The manganese of about 1.03%-1.18%; The silicon of about 0.15%-0.35%; Be up to about 0.003% sulphur; Be up to about 0.012% phosphorus; Be up to about 0.10% nickel; The chromium of about 0.63%-0.73%; The molybdenum of about 0.40%-0.45%; The vanadium of about 0.03%-0.05%; The titanium of about 0.025%-0.035%; The copper of about 0.15%-0.30%; The aluminium of about 0.010%-0.050%; Be up to about 0.05% niobium; Be up to about 0.15% residual element; And the iron of equal amount and inevitable impurity.

4, according to the low-carbon alloy steel of claim 1, wherein steel pipe has the yield strength at least about 125ksi.

5, according to the low-carbon alloy steel of claim 1, wherein steel pipe has the yield strength at least about 135ksi.

6, according to the low-carbon alloy steel of claim 1, wherein steel pipe has the extension at least about 9%.

7, according to the low-carbon alloy steel of claim 1, wherein steel pipe has the hardness that is no more than 40HRC.

8, according to the low-carbon alloy steel of claim 1, wherein steel pipe has the hardness that is no more than 37HRC.

9, according to the low-carbon alloy steel of claim 1, wherein steel pipe has and is lower than about 0.63% carbon equivalent, and carbon equivalent is determined according to following formula:

Ceq＝％C+％Mn/6+(％Cr+％Mo+％V)/5+(％Ni+％Cu)/15

10, according to the low-carbon alloy steel of claim 9, wherein steel pipe has and is lower than about 0.60% carbon equivalent.

11, according to the low-carbon alloy steel of claim 9, wherein steel pipe has and is lower than about 0.56% carbon equivalent.

12, according to the low-carbon alloy steel of claim 1, wherein steel pipe maximum contaminant content is 2 or lower-thin series and 1 or lower-thick series, adopts the substandard criterion of ASTM E45-Worst Field Method (method A).

13, according to the low-carbon alloy steel of claim 1, wherein steel pipe is as follows according to the maximum contaminant content that the substandard criterion of ASTM E45-WorstField Method (method A) has: Dopant type Thin Thick A 0.5 0 B 1.5 1.0 C 0 0 D 1.5 0.5

14, according to the low-carbon alloy steel of claim 13, wherein the excessive contaminant size of Huo Deing is 30 microns or littler.

15, according to the low-carbon alloy steel of claim 14, wherein total oxygen level is limited to 20ppm.

16, according to the low-carbon alloy steel of claim 1, wherein steel pipe has jointless construction.

17, a kind of gas storage aerator pressurized vessel that comprises the low-carbon alloy steel pipe of claim 1.

18, a kind of automotive airbag aerator that comprises the low-carbon alloy steel pipe of claim 1.

19, a kind of low-carbon alloy steel pipe is mainly composed of the following components, calculates by weight: the carbon of about 0.08%-0.11%; The manganese of about 1.03%-1.18%; The silicon of about 0.15%-0.35%; Be up to about 0.003% sulphur; Be up to about 0.012% phosphorus; Be up to about 0.10% nickel; The chromium of about 0.63%-0.73%; The molybdenum of about 0.40%-0.45%; The vanadium of about 0.03%-0.05%; The titanium of about 0.025%-0.35%; The copper of about 0.15%-0.30%; The aluminium of about 0.010%-0.050%; Be up to about 0.05% niobium; Be up to about 0.15% residual element; And the iron of equal amount and inevitable impurity, wherein steel pipe has at least about the tensile strength of 145ksi and is lower than tough-crisp transition temperature of-60 ℃.

20, according to the low-carbon alloy steel of claim 19, wherein steel pipe has jointless construction.

21, a kind of gas storage aerator pressurized vessel that comprises the low-carbon alloy steel pipe of claim 19.

22, a kind of automotive airbag aerator that comprises the low-carbon alloy steel pipe of claim 19.

23, a kind of method that is used for gas storage aerator pressurized vessel steel pipe of making certain-length may further comprise the steps:

Produce the pipe of certain-length by steel, described steel are mainly composed of the following components, calculate by weight: the carbon of about 0.06%-0.18%, the manganese of about 0.5%-1.5%, the silicon of about 0.1%-0.5% is up to about 0.015% sulphur, is up to about 0.025% phosphorus, be up to about 0.50% nickel, the chromium of about 0.1%-1.0%, the molybdenum of about 0.1%-1.0%, the vanadium of about 0.01%-0.1%, the titanium of about 0.01%-0.1%, the copper of about 0.05%-0.35%, the aluminium of about 0.010%-0.050% is up to about 0.05% niobium, be up to about 0.15% residual element, and the iron of equal amount and inevitable impurity;

Above-mentioned steel pipe is cold drawn to obtain required size;

Austenitizing, by heat cold-drawn steel pipe Ac3 extremely at least in induction type austenitizing stove, heating rate is at least about 100 ℃ of per seconds;

After the heating steps, in quench fluid, extinguish steel pipe until pipe near room temperature, rate of cooling is at least about 100 ℃ of per seconds; With

After extinguishing step, be lower than under the temperature of Ac1 the tempering steel pipe 2-30 minute.

24, according to the method for claim 23, wherein the steel pipe of being produced is mainly composed of the following components, calculates by weight: the carbon of about 0.07%-0.12%; The manganese of about 1.00%-1.40%; The silicon of about 0.15%-0.35%; Be up to about 0.010% sulphur; Be up to about 0.015% phosphorus; Be up to about 0.20% nickel; The chromium of about 0.55%-0.80%; The molybdenum of about 0.30%-0.50%; The vanadium of about 0.01%-0.07%; The titanium of about 0.01%-0.05%; The copper of about 0.15%-0.30%; The aluminium of about 0.010%-0.050%; Be up to about 0.05% niobium; Be up to about 0.15% residual element; And the iron of equal amount and inevitable impurity.

25, according to the method for claim 23, wherein the steel pipe of being produced is mainly composed of the following components, calculates by weight: the carbon of about 0.08%-0.11%; The manganese of about 1.03%-1.18%; The silicon of about 0.15%-0.35%; Be up to about 0.003% sulphur; Be up to about 0.012% phosphorus; Be up to about 0.10% nickel; The chromium of about 0.63%-0.73%; The molybdenum of about 0.40%-0.45%; The vanadium of about 0.03%-0.05%; The titanium of about 0.025%-0.035%; The copper of about 0.15%-0.30%; The aluminium of about 0.010%-0.050%; Be up to about 0.05% niobium; Be up to about 0.15% residual element; And the iron of equal amount and inevitable impurity.

26, according to the method for claim 23, the steel pipe that wherein obtains has the yield strength at least about 125ksi.

27, according to the method for claim 23, the steel pipe that wherein obtains has the yield strength at least about 135ksi.

28, according to the method for claim 23, the steel pipe that wherein obtains has the tensile strength at least about 145ksi.

29, according to the method for claim 23, the steel pipe that wherein obtains has the extension at least about 9%.

30, according to the method for claim 23, the steel pipe that wherein obtains has the hardness that is no more than 40HRC.

31, according to the method for claim 23, the steel pipe that wherein obtains has the hardness that is no more than 37HRC.

32, according to the method for claim 23, the steel pipe that wherein obtains has and is lower than tough-crisp transition temperature of-60 ℃.

33, according to the method for claim 23, wherein in the austenitizing heating steps, steel pipe is heated to about 920-1050 ℃.

34, according to the method for claim 33, wherein in the austenitizing heating steps, the heating rate of steel pipe is at least about 200 ℃ of per seconds.

35, according to the method for claim 23, wherein in extinguishing step, the rate of cooling of steel pipe is at least about 200 ℃ of per seconds.

36, according to the method for claim 23, wherein in tempering step, steel pipe tempering between about 400-600 ℃ temperature.

37, according to the method for claim 23, wherein in tempering step, the steel pipe tempering time is about 4-20 minute.

38, according to the method for claim 23, further comprise the arrangement step wherein the tempered steel pipe by acidleach, phosphorylation with oil.

39, a kind of method of making the steel pipe that is used for gas storage aerator pressurized vessel of certain-length may further comprise the steps:

By the pipe of steel production certain-length, described steel are mainly composed of the following components, calculate by weight:

The carbon of about 0.08%-0.11%, the manganese of about 1.03%-1.18%, the silicon of about 0.15%-0.35%, be up to about 0.003% sulphur, be up to about 0.012% phosphorus, be up to about 0.10% nickel, the chromium of about 0.63%-0.73%, the molybdenum of about 0.40%-0.45%, the vanadium of about 0.03%-0.05%, the titanium of about 0.025%-0.035%, the copper of about 0.15%-0.30%, the aluminium of about 0.010%-0.050% is up to about 0.05% niobium, be up to about 0.15% residual element, and the iron of equal amount and inevitable impurity;

Above-mentioned steel pipe is cold drawn to obtain required size;

Austenitizing, by the heating cold-drawn steel pipe is to 920-1050 ℃ in induction type austenitizing stove, heating rate is at least about 200 ℃ of per seconds;

After the heating steps, in quench fluid, extinguish steel pipe until pipe near room temperature, rate of cooling is at least about 200 ℃ of per seconds; With

After extinguishing step, the tempering steel pipe is 4-20 minute under 450-550 ℃ temperature,

The arrangement step wherein the tempered steel pipe by acidleach, phosphorylation with oil,

Wherein the steel pipe after the arrangement has the yield strength at least about 135ksi, the tensile strength of 145ksi, and extension is at least about 9%, and hardness is not more than 37HRC, is lower than tough-crisp transition temperature and good surface appearance of-60 ℃.