CN101045978A - Manufacturing method for seamless steel pipe - Google Patents
Manufacturing method for seamless steel pipe Download PDFInfo
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- CN101045978A CN101045978A CN 200710088963 CN200710088963A CN101045978A CN 101045978 A CN101045978 A CN 101045978A CN 200710088963 CN200710088963 CN 200710088963 CN 200710088963 A CN200710088963 A CN 200710088963A CN 101045978 A CN101045978 A CN 101045978A
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- 229910000831 Steel Inorganic materials 0.000 title claims abstract description 90
- 239000010959 steel Substances 0.000 title claims abstract description 90
- 238000004519 manufacturing process Methods 0.000 title claims abstract description 36
- 238000005096 rolling process Methods 0.000 claims abstract description 60
- 238000003303 reheating Methods 0.000 claims abstract description 21
- 229910052799 carbon Inorganic materials 0.000 claims abstract description 17
- 230000009466 transformation Effects 0.000 claims abstract description 16
- OKTJSMMVPCPJKN-UHFFFAOYSA-N Carbon Chemical compound [C] OKTJSMMVPCPJKN-UHFFFAOYSA-N 0.000 claims abstract description 15
- 238000010438 heat treatment Methods 0.000 claims abstract description 14
- 238000005098 hot rolling Methods 0.000 claims abstract description 10
- 229910052748 manganese Inorganic materials 0.000 claims abstract description 7
- 229910052804 chromium Inorganic materials 0.000 claims abstract description 6
- 229910052758 niobium Inorganic materials 0.000 claims abstract description 6
- 229910052720 vanadium Inorganic materials 0.000 claims abstract description 6
- 238000000034 method Methods 0.000 claims description 42
- 238000001816 cooling Methods 0.000 claims description 13
- 229910052739 hydrogen Inorganic materials 0.000 claims description 13
- 238000005553 drilling Methods 0.000 claims description 11
- 239000012535 impurity Substances 0.000 claims description 11
- 229910052760 oxygen Inorganic materials 0.000 claims description 9
- 229910052802 copper Inorganic materials 0.000 claims description 5
- 229910052757 nitrogen Inorganic materials 0.000 claims description 5
- -1 S is below 0.005% Substances 0.000 claims description 3
- 229910052717 sulfur Inorganic materials 0.000 claims description 2
- 239000003129 oil well Substances 0.000 abstract description 11
- 229910052782 aluminium Inorganic materials 0.000 abstract description 2
- 229910052710 silicon Inorganic materials 0.000 abstract description 2
- 230000033228 biological regulation Effects 0.000 description 39
- 238000012545 processing Methods 0.000 description 23
- 230000000694 effects Effects 0.000 description 16
- 239000000126 substance Substances 0.000 description 16
- 238000012360 testing method Methods 0.000 description 15
- 238000009863 impact test Methods 0.000 description 10
- 239000013078 crystal Substances 0.000 description 9
- 239000000463 material Substances 0.000 description 9
- 238000007669 thermal treatment Methods 0.000 description 9
- UFHFLCQGNIYNRP-UHFFFAOYSA-N Hydrogen Chemical compound [H][H] UFHFLCQGNIYNRP-UHFFFAOYSA-N 0.000 description 8
- 239000001257 hydrogen Substances 0.000 description 8
- 229910001563 bainite Inorganic materials 0.000 description 6
- 229910000734 martensite Inorganic materials 0.000 description 6
- 230000008569 process Effects 0.000 description 6
- 238000010079 rubber tapping Methods 0.000 description 6
- 208000037656 Respiratory Sounds Diseases 0.000 description 5
- 239000000203 mixture Substances 0.000 description 5
- QVGXLLKOCUKJST-UHFFFAOYSA-N atomic oxygen Chemical compound [O] QVGXLLKOCUKJST-UHFFFAOYSA-N 0.000 description 4
- 229910001566 austenite Inorganic materials 0.000 description 4
- 239000001301 oxygen Substances 0.000 description 4
- 238000012856 packing Methods 0.000 description 4
- 229910000859 α-Fe Inorganic materials 0.000 description 3
- 230000009471 action Effects 0.000 description 2
- 230000009975 flexible effect Effects 0.000 description 2
- 239000004615 ingredient Substances 0.000 description 2
- 229910052751 metal Inorganic materials 0.000 description 2
- 238000013508 migration Methods 0.000 description 2
- 230000005012 migration Effects 0.000 description 2
- 235000019362 perlite Nutrition 0.000 description 2
- 239000010451 perlite Substances 0.000 description 2
- 238000010791 quenching Methods 0.000 description 2
- 230000009467 reduction Effects 0.000 description 2
- 238000004513 sizing Methods 0.000 description 2
- 230000000996 additive effect Effects 0.000 description 1
- 238000000137 annealing Methods 0.000 description 1
- 230000008901 benefit Effects 0.000 description 1
- 230000015572 biosynthetic process Effects 0.000 description 1
- 230000000052 comparative effect Effects 0.000 description 1
- 238000012937 correction Methods 0.000 description 1
- 238000006356 dehydrogenation reaction Methods 0.000 description 1
- 238000009795 derivation Methods 0.000 description 1
- 238000005516 engineering process Methods 0.000 description 1
- 238000011156 evaluation Methods 0.000 description 1
- 230000005764 inhibitory process Effects 0.000 description 1
- 238000003754 machining Methods 0.000 description 1
- 238000002844 melting Methods 0.000 description 1
- 230000008018 melting Effects 0.000 description 1
- 238000012797 qualification Methods 0.000 description 1
- 230000000171 quenching effect Effects 0.000 description 1
- 238000005204 segregation Methods 0.000 description 1
- 238000002791 soaking Methods 0.000 description 1
- 238000009628 steelmaking Methods 0.000 description 1
- 238000005496 tempering Methods 0.000 description 1
- 238000009864 tensile test Methods 0.000 description 1
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Abstract
The invention provides an efficient manufacturing method for excellent seamless steel pipe used as oil well pipe. It meets the N80-level strength requirements of API specification and has excellent toughness. After heating the steel billet containing C: 0.30~0.45%, Si: below 0.50%, Mn: 1.0~2.0%, Cr: 0.2~1.0 %, V: 0.02~0.20%, Nb: 0.005~0.050% and Al: below 0.050% according to mass percentage, perforating it, carrying out hot rolling according to more than 30% sectional area's finishing degree by mandrel mill, the steel billet is cooled to a temperature below Ar<SUB>1</SUB> transformation point, and then heated by reheating furnace to a temperature between Ac<SUB>3</SUB> and Ac<SUB>3</SUB> plused by 30 degrees and sectional area's finishing degree(%) obtained by drawing-rolling machine, machined by the drawing-rolling machine on conditions meeting the undermentioned formula (i), then air cooled. X: sectional area's finishing degree''%'', Ceq: carbon equivalent''%''. 552<2.04X+681.5Ceq<758 ...(i).
Description
Technical field
The manufacture method of the weldless steel tube that the present invention relates to intensity and good-toughness and be fit to as oil well pipe.
Background technology
Weldless steel tube desired strength, toughness that is used for oil well pipe etc. is good, the oil well pipe of the N80 grade of API (API) specification, and the regulation tensile strength is more than the 724MPa, yield strength is 552～758MPa.
Make the weldless steel tube of the regulation of the N80 grade that satisfies this API specification, behind tubulation, thereby generally quench, tempered thermal treatment high strength.But, in order to carry out above-mentioned thermal treatment, need the process furnace of quenching usefulness, the equipment such as holding furnace that tempering is used, thereby cost improves.
Therefore, proposed to use processing thermal treatment tubulation, do not implemented thermal treatment behind the tubulation and only carry out air cooling and just possess high-intensity oil well seamless steel pipe, and also supply in practicality.For example, in Patent Document 1 publicity following method, the heating soaking is after 900～1300 ℃, bore a hole with tapping machine, then the pipe that will implement the first time hot-work (wall thickness processing) of working modulus more than 30% with mandrel mill is cooled to the speed of cooling of regulation and is lower than 400 ℃, is heated to Ac with reheating furnace thereafter
3Above specified temperature scope is implemented the second time hot-work (undergauge or wall thickness process) of working modulus 5% or more air cooling afterwards with roller mill etc.
In addition, in Patent Document 2 publicity following method, with tapping machine and mandrel mill bore a hole with hot-work after, be chilled to temperature below 350 ℃ with the speed of cooling of regulation, subsequently at reheat to Ac
1After the temperature in the following specialized range, carry out undergauge processing with roller mill with the sectional shrinkage more than 5%, carry out air cooling afterwards, in Patent Document 3, also propose before reheating furnace is packed into, pipe to be cooled to below the transformation temperature (Ac1), carry out reheat, be refined to the drawing/rolling machine regulation size application processing heat treated manufacture method.
These methods are because can omit thermal treatment, so have the high advantage of the efficient of manufacturing.But, when the degree of finish of drawing/rolling machine all hangs down, can not satisfy the intensity of above-mentioned API specification specifies, or become the former material that toughness is low and be highly brittle.
As the measure of its solution, following method is proposed in Patent Document 4, will be cooled to Ar with the former material of mandrel mill hot rolled
1After the temperature below the point, use the reheating furnace reheat to Ac
3Transformation temperature～Ac
3Transformation temperature+50 ℃, thus make the structural transformation of bainite or martensite main body become austenite structure, and then, before roller mill is rolling, evenly be cooled to 700～780 ℃ after, rolling with the roller mill undergauge.According to this method, can be met high tenacity, the high strength seamless steel pipe of the N80 grade regulation of API specification.But, added above-mentioned homogeneous refrigerating work procedure because before roller mill is rolling, pay, make the shortcoming that efficient reduces greatly so have.
Patent Document 1: the spy opens flat 2-254122 communique
Patent Document 2: the spy opens clear 63-96215 communique
Patent Document 3: the spy opens flat 3-107421 communique
Patent Document 4: the spy opens flat 6-240357 communique
As mentioned above, used in the manufacture method of the heat treated weldless steel tube of existing processing, will be cooled to the temperature range of regulation with mandrel mill hot rolled pipe after, the reheating furnace reheat of packing into.But, be rolled in machine rolling the problem that exists the intensity that can not be met above-mentioned API specification specifies or toughness to reduce when its degree of finish is low afterwards.Before roller mill is rolling, increase homogeneous refrigerative operation for addressing this problem, make efficient and reduce greatly.
Summary of the invention
The present invention constitutes in light of this situation, its purpose is, a kind of manufacture method of weldless steel tube is provided, make weldless steel tube efficiently with processing thermal treatment as oil well pipe, this weldless steel tube satisfies the intensity regulation of the N80 grade of API specification, and (tensile strength: 724MPa is above, yield strength: 552MPa～758MPa), and toughness is also excellent.
For addressing the above problem, present inventors have repeated to inquire into the efficient processing thermal treatment that is suitable for.Consequently, judgement is before the reheating furnace of will being packed into by the pipe after the mandrel mill hot rolling, need be phase-changed into martensite, bainite, ferrite, perlite or their mixed structure any (being preferably martensite or bainite), make structure refinement, make the pipe after the hot rolling be cooled to Ar
1Below the transformation temperature.Used in the manufacturing of the heat treated weldless steel tube of existing processing, because with reinstalling reheating furnace after the mandrel mill hot rolling usually, so produce the problem of described intensity, toughness reduction.This problem can not solve with the method for above-mentioned Patent Document 1～3 motion.
In addition, present inventors find, between the degree of finish (sectional area degree of finish) that chemical ingredients of suitable steel (at this moment being carbon equivalent) and suitable employing drawing/rolling machine obtain dependency are arranged.In addition,, also consider the degree of finish that employing drawing/rolling machine obtains, then just be judged as and reasonably carry out the setting of the Heating temperature upper limit if on the basis of the Heating temperature condition in the decision reheating furnace.
The present invention is based on this opinion, its purport is the manufacture method of following weldless steel tube.
That is, a kind of manufacture method of weldless steel tube at the heating steel billet, and with after the perforation of drilling/rolling machine, is implemented hot rolling with mandrel mill with the sectional area degree of finish more than 30% and is processed into pipe, and this pipe is cooled to Ar
1Below the transformation temperature, then, be heated to Ac with reheating furnace
3～(Ac
3The sectional area degree of finish (%) that+30 ℃+employing drawing/rolling machine obtains) after the temperature range, condition with drawing/rolling machine following to satisfy (i) formula is processed, carry out air cooling then, wherein, described steel billet contains in quality %: C:0.30～0.45%, below the Si:0.50%, Mn:1.0～2.0%, Cr:0.2～1.0%, V:0.02～0.20%, Nb:0.005～0.050% and below the Al:0.050%, surplus is Fe and impurity, is below 0.05% as the P of impurity, S is below 0.005%, Cu is below 0.05%, N is below 0.030%, O (oxygen) is below 0.005%, H is below 0.0005%.
552＜2.04X+681.5C
eq＜758 …(i)
Here, X: the sectional area degree of finish " % " that adopts the drawing/rolling machine to obtain
C
Eq: the carbon equivalent of representing with following formula " % "
C
eq＝C+Mn/5+Si/7+(Cu+Cr)/9+Ni/22+V/2
In the formula of the above-mentioned carbon equivalent of expression, each symbol of element such as C, Mn is meant the content (quality %) of each element.
Here " sectional area degree of finish " is the degree of finish of representing with the decrement of the sectional area of the pipe before and after the processing.That is, use the degree of finish that { sectional area before (sectional area after the sectional area-processing before the processing)/processing } * 100 (%) try to achieve.
In the manufacture method of the weldless steel tube of the invention described above, steel billet contains above-mentioned chemical ingredients, can also contain in quality %: C:0.30～0.45%, below the Si:0.50%, Mn:1.0～2.0%, Cr:0.2～1.0%, V:0.02～0.20%, Nb:0.005～0.050% and below the Al:0.050%, also contain below the Ni:0.10%, below the Mo:0.10% and in below the Ti:0.05% one or more, surplus is Fe and impurity, is below 0.05% as the P of impurity, S is below 0.005%, Cu is below 0.05%, N is below 0.030%, O (oxygen) is below 0.005%, H is below 0.0005%.
Manufacture method according to weldless steel tube of the present invention, (tensile strength: 724MPa is above, yield strength: 552MPa～758MPa), and the also excellent weldless steel tube as oil well pipe of toughness can to use processing thermal treatment high efficiency manufacturing to satisfy the intensity regulation of the N80 grade of API specification.
Description of drawings
It is graceful that Fig. 1 is that weldless steel tube is made in the explanation hot rolling is the figure of one of the manufacturing process example of this graceful tubulation method;
Fig. 2 is the figure of carbon equivalent with the relation of the sectional area degree of finish that adopts the drawing/rolling machine to obtain of expression steel;
Fig. 3 represents the hydrogen richness of steel billet and the figure of the relation that the hydrogen crackle takes place.
Nomenclature
1: circular steel billet
2: the hollow pipe
3: the drilling/rolling machine
4: mandrel mill
4r: roll
5: reheating furnace
6: the drawing/rolling machine
Embodiment
Below, with regard to the manufacture method of weldless steel tube of the present invention, comprise chemical constitution that is defined as above the steel that constitutes this steel pipe and the reason of creating conditions, carry out specific description.
At first, the action effect of each composition that contains in the narration steel and the qualification reason of its content.In addition, ' % ' of each composition is meant " quality % ".
C：0.30～0.45％
C is the indispensable element that is used to improve the intensity of the weldless steel tube made from method of the present invention.C content is lower than 30%, just can not obtain full intensity.In addition, if C content surpasses 45%, then toughness reduces, and the cross section migration temperature of pendulum impact test is more than 0 ℃, therefore becomes the problem in the practicality sometimes.Not about the regulation of pendulum impact test, still, preferred cross-sections migration temperature is for being lower than 0 ℃ in the practicality in the N80 of API specification grade.
Below the Si:0.50%
Because Si has desoxydatoin, so preferred a small amount of the interpolation.But, because excessive interpolation toughness can worsen, so the upper limit of Si content is set at 0.50%.Even a spot of interpolation also is resultful, therefore, the lower limit of Si content is unqualified, still, for obtaining obvious effects, preferably contains more than 0.05%.
Mn：1.0～2.0％
Owing to as above stipulate to improve the upper limit of C content of the intensity of steel like that, therefore, Mn is the element that the high strength with the weldless steel tube of method manufacturing of the present invention is played very large effect.The content of Mn is lower than at 1.0% o'clock, the intensity that can not obtain stipulating, and in addition, if content surpasses 2.0%, then toughness worsens.Therefore, Mn content is set at 1.0～2.0%.
Cr：0.2～1.0％
Cr is one of the element that must add that is used for the high strength of steel.The content of Cr is lower than at 0.2% o'clock, the intensity that can not obtain stipulating, if content surpasses 1.0%, then thick Cr carbide produces in a large number, and toughness is reduced, and therefore, the content of Cr is set at 0.2～1.0%.
V：0.02～0.20％
V is used to obtain high strength, the necessary element of high yield ratio (yield-point/tensile strength).The low more crystal grain of sectional area working modulus during with the precision work of drawing/rolling machine is thickization more, and yield ratio descends, and therefore, adds V and must obtain high strength, high yield ratio.The content of V is lower than at 0.02% o'clock, and the additive effect of V can not find full expression.In addition, if content surpasses 0.20%, then toughness descends.Therefore, the content of V is set at 0.02～0.20%.
Nb：0.005～0.050％
Nb has the NbC of separating out, and when heating with reheating furnace, by the pinning effect the thick effect of the crystal grain of inhibition is arranged.The addition of Nb is lower than at 0.005% o'clock, and its effect can not find full expression, and content surpasses at 0.050% o'clock, and toughness descends.Therefore, the content of Nb is set at 0.005～0.050%.
Below the Al:0.050%
Al has dehydrogenation, so can use in the steel-making stage.But excessive containing sometimes, toughness worsens, and therefore, the content of Al is set in below 0.050%.
With the weldless steel tube of method manufacturing of the present invention be contain above-mentioned composition, surplus is the steel pipe of Fe and impurity.As impurity, regulation P below 0.05%, S below 0.005%, Cu below 0.05%, N below 0.030%, O (oxygen) below 0.005%, H is below 0.0005%, it be the reasons are as follows.
P separates out at crystal boundary, and toughness is extremely worsened.Preferred P is few more good more, and molten steel contains more P usually, is the element of unavoidably sneaking into.Therefore, the upper limit with the tolerable limit of P content is set at 0.05%.
S is because segregation, and toughness is extremely worsened.Preferred S is few more good more, is the element of unavoidably sneaking into same with P.Therefore, the upper limit with the tolerable limit of S content is set at 0.005%.
Cu content hot workability for a long time worsens, so few more good more.Therefore, the upper limit with Cu content is set at 0.05%.
N invades the molten steel from atmosphere.Its content surpasses 0.030% o'clock toughness to be worsened, and therefore the upper limit with the allowed band of N content is set at 0.030%.
O (oxygen) invades when melting in the steel, and the inclusion in the steel increases toughness and worsens.Therefore, O content is set at below 0.005%.Be preferably below 0.003%.
When H was present in the steel in the steel billet stage, steel billet caused the hydrogen crackle, and the manufacturing of steel pipe can not be carried out.Therefore, the content of H is necessary for (with reference to Fig. 3 described later) below 0.0005% in the steel billet stage.Be preferably below 0.0002%.For satisfying this condition, as long as carry out the adjustment of the hydrogen richness of annealing softening etc. by steel billet.
Weldless steel tube with method manufacturing of the present invention not only contains in the above-mentioned composition (C, Si, Mn, Cr, V, Nb and Al), can also contain below the Ni:0.10%, below the Mo:0.10% and in below the Ti:0.05% one or more.Why action effect and the content with these compositions is limited to above-mentioned scope, is because following reason is arranged.
Below the Ni:0.10%
Ni has the flexible action effect that improves steel, therefore, as long as add as required.Because it is valuable metallic element, thus a large amount of contain sometimes that the goods cost increases, unfavorable to economy, so the upper limit of Ni content is set at 0.10%.Even a small amount of interpolation also produces effect, so the lower limit of Ni content do not limit, and still, contains more than 0.03% for obtaining obvious effects, being preferably.
Below the Mo:0.10%
Mo rises carbon equivalent, and the element useful to the high strength of steel can add as required.Since with Ni be valuable metallic element equally, therefore the upper limit with its content is set at 0.10%.Even a small amount of interpolation also produces effect, so the lower limit of Mo content do not limit, and still, contains more than 0.03% for obtaining obvious effects, being preferably.
Below the Ti:0.05%
Ti has when making the low material high strength of processibility improve carbon equivalent, prevents the effect of the crackle of steel billet, therefore can add as required.When carbon equivalent 0.80 was above, its effect was remarkable especially.But the toughness that Ti added dimension can reduce, so the upper limit of Ti content is set at 0.05%.Even a small amount of interpolation also produces effect, so the lower limit of Ti content do not limit, and still, contains more than 0.02% for obtaining obvious effects, being preferably.
Narration is created conditions below.
The manufacture method of weldless steel tube of the present invention is, the steel billet that heating has above-mentioned chemical constitution, after the perforation of drilling/rolling machine, implement hot rolling with mandrel mill with the sectional area degree of finish more than 30% and become pipe, this pipe is cooled to below the Ar1 transformation temperature, then be heated to the temperature range of Ac3～(the sectional area degree of finish (%) that Ac3+30 ℃+employing drawing/rolling machine obtains) with reheating furnace, afterwards, condition with drawing/rolling machine above-mentioned to satisfy (i) formula is processed, and then carries out air cooling.
Before explanation limits the reason of creating conditions of weldless steel tube like this, be that this graceful tubulation method is summarized at first to general the graceful of manufacture method application as weldless steel tube.
Making the graceful of weldless steel tube under the thermal environment is that this graceful tubulation method is made of following operation: the perforation process of the central part perforate of middle real steel billet, with the wall thickness of the hollow pipe of this perforation be processed as main purpose the extension rolling process, make pipe external diameter tube reducing and be refined to the fixed diameter rolling operation of target size.
Usually, using graceful in perforation process is drilling/rolling machines such as this graceful tapping machine, chiasma type drilling/rolling machine, pressure pierce roller mill, extending roller mills such as rolling process use mandrel mill, mandrel mill, Assel mill, in addition, in the fixed diameter rolling operation, use drawing/rolling machine and sizing mill diplodal roller mill respectively.
It is graceful that Fig. 1 is that weldless steel tube is made in the explanation hot rolling is the figure of one of the manufacturing process example of this graceful tubulation method.This pipe-making method be will be heated to specified temperature middle real circular steel billet 1 as being rolled material, should flow to drilling/rolling machine 3 by circle steel billet 1, hollow pipe 2 is made in the perforation of its axle center part.Subsequently, the hollow pipe of making 2 directly or is as required carried out hole enlargement, thin-walled property by the elongating mill with the same formation of above-mentioned drilling/rolling machine, afterwards, the extension reduction unit that flows to follow-up mandrel mill 4 extends rolling.
Extend when rolling with mandrel mill 4, hollow pipe 2 extends by the core bar 4b that packs into and the roll 4r of restriction pipe outside, and cooling simultaneously.Therefore, the hollow pipe 2 that has passed through mandrel mill 4 reheating furnace 5 of packing into once more subsequently carries out reheat.Afterwards, grind pipe, shape corrections and sizing, create the weldless steel tube of goods through above-mentioned finishing procedure by drawing/rolling machine 6.
In the manufacture method of weldless steel tube of the present invention, at first, the steel billet that heating has above-mentioned chemical constitution becomes the hollow tube base with the perforation of drilling/rolling machine.Be to use drilling/rolling machine shown in Figure 13 to make the perforation process of the plain pipe 2 of hollow.
At this moment there is no particular limitation for the Heating temperature of steel billet.Preferably in 1150～1250 ℃ that carry out usually temperature range, heat.Also, make heat-up time at the central part of said temperature scope internal heating to steel billet as long as suit decision.Usually preferred 2～4 hours.In addition, perforation also can use above-mentioned graceful be any drilling/rolling machine outside this graceful tapping machine.Used tapping machine in an embodiment of the present invention.
Afterwards, this hollow pipe is implemented hot-work (below be also referred to as " time processing ") with mandrel mill with the sectional area degree of finish more than 30%, obtain pipe.Promptly extend rolling process.
It is in order to make the crystal grain miniaturization, to be lower than at 30% o'clock that the sectional area degree of finish is set at more than 30%, and miniaturization is insufficient.
Subsequently this pipe is cooled to A
R1Below the transformation temperature.This is for before packing reheating furnace at the pipe behind the hot rolling that will be undertaken by mandrel mill as mentioned above, be phase-changed into martensite, bainite, ferrite, perlite or their mixed structure any and make structure refinement.Under this situation, manufacturing efficient is reduced, therefore preferred phase transformation to martensite or bainite to the time-consuming ferrite of cooling, pearlitic phase transformation.
Then, above-mentioned cooled pipe is heated to A with reheating furnace
C3～(A
C3The sectional area degree of finish (%) that+30+ adopts the drawing/rolling machine to obtain) temperature range.
The reheat temperature is set at A
C3Be in order to be cooled to A before packing into to reheating furnace more than the transformation temperature
R1Below the transformation temperature, by being heated to A
C3Transformation temperature above and again anti-phase become austenite structure, make structure refinement.
On the other hand, the upper limit of reheat temperature such as above-mentioned mode being limited is in order to prevent thickization of austenite crystal.When the sectional area degree of finish that the drawing/rolling machine obtains hangs down, follow the refinement of crystal grain of processing insufficient, crystal grain is thick, and intensity, toughness also reduce.Therefore, reduce the reheat temperature more, just need further to stop thickization of austenite crystal.Therefore, in the formula of expression reheat upper temperature limit, inserted " the sectional area degree of finish (%) that adopts the drawing/rolling machine to obtain ".
That is when in reheating furnace, formulating the Heating temperature condition, not the A that will determine according to steel grade separately,
C3Transformation temperature is as benchmark, but will be at A
C3Increase on the transformation temperature temperature that the sectional area degree of finish (%) will adopt the drawing/rolling machine to obtain changes (℃) the temperature of numerical value be benchmark, because the sectional area degree of finish during by the drawing/rolling machining is reflected on the reheat temperature the influence of crystal grain miniaturization, so the upper limit that can more rational setting reheat temperature.
Then, the pipe of reheat is implemented processing with the drawing/rolling machine under the condition that satisfies above-mentioned (i) formula.Shown in Figure 1 be by drawing/rolling machine 6 the fixed diameter rolling operation.
Why make such regulation and be because, as follows, between the sectional area degree of finish (X) that chemical constitution of suitable steel (carbon equivalent Ceq) and suitable employing drawing/rolling machine obtain dependency is arranged, by under the condition that satisfies (i) formula, implementing processing, can be met the intensity regulation of the N80 grade of this API specification.
Fig. 2 is the figure of carbon equivalent with the relation of the sectional area degree of finish that adopts the drawing/rolling machine to obtain of expression steel.With carbon equivalent (Ceq) and sectional area degree of finish (X) as diaxon, in embodiment described later, the pipe of chemical constitution in the scope of the present invention's regulation to steel, the value of carbon equivalent and sectional area degree of finish is made into figure, zero expression yield strength and tensile strength satisfy the value of the intensity regulation of API specification N80 grade, the value the beyond * expression regulation.
With straight line L among the figure and straight line H represent above-mentioned zero and * boundary, be the zone of intensity regulation of satisfying the N80 grade of API specification near straight line L top, near the zone of the below of straight line H.
Straight line L can be expressed as " 552=2.04X+681.5Ceq " from its obliquity and the position on coordinate, and the zone of this straight line L top can be expressed as " 552＜2.04X+681.5Ceq ".In addition, straight line H can be expressed as " 2.04X+681.5Ceq=758 " from its obliquity and the position on coordinate with figure, and the zone of the below of this straight line H can be expressed as " 2.04X+681.5Ceq＜758 ".
" 552＜2.04X+681.5Ceq " of the region representation above this straight line L and " 2.04X+681.5Ceq＜758 " of the region representation below the straight line H are combined into 552＜2.04X+681.5Ceq＜758, promptly obtain (i) formula.Satisfy should (i) formula the zone, be the zone of " specialized range of the present invention " expression among Fig. 2, be the zone of intensity regulation of satisfying the N80 grade of API specification.
Like this, above-mentioned (i) formula is by the carbon equivalent (Ceq) in the test of most tubulations and adopts sectional area degree of finish (X) that the drawing/rolling machine obtains, and the conditional of the relation derivation of the intensity (yield strength, tensile strength) of the weldless steel tube that obtains this moment.
In addition, comprising straight line L below it, not satisfying the intensity regulation (be expressed as " undercapacity ") of the N80 grade of API specification in Fig. 2, comprising the zone of straight line H above it, is (be expressed as in Fig. 2 " cross intensity ") outside the intensity regulation of API specification.
After the processing of the drawing/rolling machine of stating on the implementation, carry out air cooling.
The manufacture method of weldless steel tube according to the present invention as described hereinbefore, (tensile strength: 724MPa is above, the oil well pipe of yield strength: 552MPa～758MPa) can to make the intensity regulation of the N80 grade that satisfies the API specification expeditiously with processing thermal treatment.And, have above-mentioned chemical constitution because constitute the steel of this weldless steel tube, so toughness is also excellent.
Embodiment
Utilization possess above-mentioned operation shown in Figure 1 weldless steel tube producing apparatus (wherein, between mandrel mill 4 and reheating furnace 5, set up the water-jet cooling apparatus), the steel pipe of principal dimension is estimated the tensile strength and the yield strength that are defined as same specification in the oil well pipe of the N80 grade of manufacturing API specification.
At first, making has the (note of the holding concurrently A of chemical constitution shown in the table 1
C3Transformation temperature) steel billet of diameter 225mm.With after this heating of pipe blank to 1200 ℃, bore a hole via tapping machine.Afterwards, implement 1 time with mandrel mill with the sectional area degree of finish more than 30% and process and the pipe of manufacturing diameter 200mm, this pipe is cooled to A by water-jet
R1The temperature range that transformation temperature is following.Subsequently, be heated to A with reheating furnace
C3Transformation temperature～(A
C3The sectional area degree of finish (%) that+employing drawing/rolling machine obtains) after the temperature range, carries out 2 processing (final precision work), carry out air cooling afterwards, obtain the weldless steel tube of specified dimension with the drawing/rolling machine.
From each steel pipe that obtains with aforesaid method, cut out arcuation test film (test film shape: P2 or P3) based on the API specification, implement tension test by tensile testing machine.
The evaluation of stretch test result is a benchmark with the regulation (yield strength: 552MPa～758MPa, tensile strength: more than the 724MPa) of the N80 grade of API specification, when satisfying this regulation, is evaluated as " well ".
In addition, there is not regulation in the N80 grade of API specification about pendulum impact test, but consider to make to use and go up no problem steel, in pendulum impact test, add and to be evaluated as the prerequisite of " well " in the ductility fracture rate of 0 ℃ of test temperature more than 50%.
Table 2～table 4 expression test-results.In table 2～table 4, it is that the drawing/rolling machine carries out external diameter, wall thickness and the sectional area degree of finish at this moment after the processing 2 times that " external diameter ", " wall thickness " on " pipe " hurdle reaches " sectional area degree of finish ".In addition, " K " value is meant, to the X (the sectional area degree of finish that adopts the drawing/rolling machine to obtain) of " 2.04X+681.5Ceq " and Ceq (carbon equivalent) value calculated of input value respectively.If this K value (i.e. " 2.04X+681.5Ceq ") greater than 552, then shows the zone of straight line L top among Fig. 2, if the K value, then shows the zone of straight line H below less than 758.
In addition, Fig. 3 is the hydrogen richness of expression steel billet and the graph of a relation that the hydrogen crackle takes place.With reference to this Fig. 3, the hydrogen content of steel billets that is used in the present embodiment test can not cause the hydrogen crackle all below 0.0004%.
Table 1
| The material numbering | Chemical constitution [quality %, surplus are Fe and impurity] | Ac 3The point [℃] | |||||||||||||||||
| C | Si | Mn | P | S | Cu | Cr | Ni | Mo | Ti | V | Nb | Al | N | O | H | Ceq | |||
| Example of the present invention | A | 0.36 | 0.43 | 1.47 | 0.028 | 0.0005 | 0.03 | 0.31 | 0.03 | 0.07 | 0.001 | 0.04 | 0.020 | 0.045 | 0.005 | 0.0032 | 0.0002 | 0.775 | 797 |
| B | 0.31 | 0.41 | 1.90 | 0.014 | 0.0008 | 0.01 | 0.24 | 0.02 | 0.03 | 0.014 | 0.06 | 0.025 | 0.029 | 0.005 | 0.0014 | 0.0003 | 0.807 | 810 | |
| C | 0.37 | 0.36 | 1.60 | 0.014 | 0.0007 | 0.02 | 0.21 | 0.02 | 0.06 | 0.023 | 0.12 | 0.032 | 0.033 | 0.004 | 0.0018 | 0.0001 | 0.828 | 793 | |
| D | 0.42 | 0.39 | 1.22 | 0.027 | 0.0006 | 0.02 | 0.32 | 0.05 | 0.02 | 0.031 | 0.13 | 0.034 | 0.038 | 0.005 | 0.0024 | 0.0001 | 0.825 | 781 | |
| E | 0.43 | 0.21 | 1.06 | 0.030 | 0.0012 | 0.02 | 0.23 | 0.05 | 0.02 | 0.041 | 0.19 | 0.015 | 0.022 | 0.005 | 0.0019 | 0.0003 | 0.797 | 774 | |
| F | 0.34 | 0.33 | 1.10 | 0.025 | 0.0008 | 0.01 | 0.25 | 0.04 | 0.05 | 0.022 | 0.06 | 0.044 | 0.037 | 0.006 | 0.0026 | 0.0002 | 0.668 | 806 | |
| G | 0.32 | 0.19 | 1.36 | 0.027 | 0.0006 | 0.02 | 0.32 | 0.01 | 0.08 | 0.035 | 0.09 | 0.021 | 0.044 | 0.003 | 0.0020 | 0.0002 | 0.702 | 806 | |
| H | 0.33 | 0.48 | 1.91 | 0.016 | 0.0009 | 0.02 | 0.32 | 0.00 | 0.03 | 0.011 | 0.14 | 0.034 | 0.038 | 0.005 | 0.0023 | 0.0002 | 0.888 | 809 | |
| I | 0.36 | 0.28 | 1.03 | 0.030 | 0.0007 | 0.01 | 0.21 | 0.04 | 0.01 | 0.044 | 0.09 | 0.022 | 0.043 | 0.008 | 0.0034 | 0.0004 | 0.677 | 797 | |
| J | 0.30 | 0.18 | 1.15 | 0.031 | 0.0006 | 0.02 | 0.25 | 0.05 | 0.02 | 0.029 | 0.06 | 0.034 | 0.039 | 0.004 | 0.0030 | 0.0002 | 0.618 | 812 | |
| K | 0.42 | 0.39 | 1.04 | 0.026 | 0.0009 | 0.03 | 0.36 | 0.02 | 0.05 | 0.014 | 0.06 | 0.034 | 0.038 | 0.005 | 0.0013 | 0.0003 | 0.758 | 782 | |
| L | 0.43 | 0.26 | 1.94 | 0.015 | 0.0012 | 0.01 | 0.26 | 0.08 | 0.01 | 0.043 | 0.11 | 0.037 | 0.048 | 0.010 | 0.0042 | 0.0003 | 0.944 | 788 | |
| M | 0.38 | 0.18 | 1.72 | 0.017 | 0.0013 | 0.01 | 0.83 | 0.03 | 0.04 | 0.024 | 0.17 | 0.035 | 0.042 | 0.007 | 0.0028 | 0.0001 | 0.929 | 785 | |
| N | 0.40 | 0.35 | 1.43 | 0.021 | 0.0005 | 0.02 | 0.61 | 0.02 | 0.01 | 0.036 | 0.18 | 0.034 | 0.024 | 0.007 | 0.0021 | 0.0002 | 0.897 | 790 | |
| O | 0.30 | 0.42 | 1.09 | 0.022 | 0.0006 | 0.01 | 0.23 | 0.01 | 0.02 | 0.016 | 0.03 | 0.012 | 0.027 | 0.008 | 0.0015 | 0.0001 | 0.620 | 809 | |
| Comparative example | P | *0.27 | 0.28 | 1.43 | 0.034 | 0.0009 | 0.03 | 0.46 | 0.03 | 0.04 | 0.029 | 0.08 | *0.061 | 0.037 | 0.008 | 0.0040 | 0.0003 | 0.692 | 809 |
| Q | 0.35 | *0.72 | 1.78 | 0.024 | 0.0007 | 0.02 | *0.16 | 0.02 | 0.05 | 0.036 | *0.22 | 0.047 | 0.021 | 0.011 | 0.0033 | 0.0002 | 0.940 | 806 | |
| R | 0.41 | 0.26 | *0.94 | 0.042 | 0.0021 | 0.03 | 0.42 | 0.04 | 0.07 | *0.061 | 0.08 | 0.014 | 0.039 | 0.013 | 0.0036 | 0.0004 | 0.727 | 780 | |
| S | 0.33 | 0.37 | 1.14 | *0.057 | 0.0013 | 0.02 | 0.24 | 0.01 | 0.03 | 0.022 | 0.16 | 0.032 | 0.042 | 0.007 | 0.0018 | 00002 | 0.720 | 808 | |
| T | 0.37 | 0.24 | 1.74 | 0.022 | *0.0060 | 0.04 | *1.03 | 0.03 | 0.03 | 0.043 | 0.07 | 0.026 | 0.041 | 0.007 | 0.0024 | 0.0001 | 0.908 | 785 | |
| U | *0.48 | 0.29 | 1.29 | 0.014 | 0.0014 | 0.04 | *0.04 | 0.03 | 0.07 | 0.034 | 0.12 | *0.003 | 0.031 | 0.008 | 0.0043 | 0.0003 | 0.850 | 783 | |
| V | 0.41 | 0.43 | *2.11 | 0.016 | 0.0017 | 0.01 | *0.15 | 0.04 | 0.06 | 0.047 | *0.01 | 0.008 | 0.037 | 0.011 | 0.0026 | 0.0002 | 0.918 | 785 | |
| W | 0.33 | 0.21 | 1.06 | 0.023 | 0.0009 | 0.03 | 0.23 | 0.08 | 0.07 | 0.031 | 0.06 | 0.024 | *0.058 | *0.032 | 0.0017 | 0.0002 | 0.635 | 804 | |
| X | 0.41 | 0.32 | 1.45 | 0.014 | 0.0008 | 0.01 | 0.34 | 0.04 | 0.06 | 0.024 | *0.22 | 0.014 | 0.023 | 0.008 | *0.0058 | 0.0001 | 0.896 | 787 | |
(remarks)
*Seal: beyond the scope of expression by the present invention's regulation.
Table 2
| Sample No. | The temperature of pipe before the reheat " ℃ " | The reheat temperature " ℃ " | Pipe | Tension test | The ductility fracture rate " % " of pendulum impact test | ||||||
| Chemical constitution | External diameter " mm " | Wall thickness " mm " | Sectional area degree of finish " % " | The K value | Yield strength " MPa " | Tensile strength " MPa " | |||||
| The material sequence number | The C equivalent | ||||||||||
| 1 | 350 | 810 | A | 0.775 | 73.03 | 5.51 | 73.1 | 677.3 | 662.1 | 850.4 | 92 |
| 2 | B | 0.807 | 73.03 | 5.51 | 73.1 | 742.0 | 679.4 | 853.6 | 95 | ||
| 3 | C | 0.828 | 73.03 | 5.51 | 73.1 | 713.4 | 700.3 | 884.2 | 90 | ||
| 4 | D | 0.825 | 73.03 | 5.51 | 73.1 | 711.3 | 705.6 | 873.3 | 92 | ||
| 5 | E | 0.797 | 73.03 | 5.51 | 73.1 | 692.3 | 701.6 | 880.7 | 93 | ||
| 6 | F | 0.668 | 73.03 | 5.51 | 73.1 | 604.4 | 600.1 | 768.4 | 98 | ||
| 7 | G | 0.702 | 73.03 | 5.51 | 73.1 | 627.5 | 628.4 | 806.9 | 95 | ||
| 8 | H | 0.888 | 73.03 | 5.51 | 73.1 | 754.3 | 740.8 | 824.8 | 86 | ||
| 9 | I | 0.677 | 73.03 | 5.51 | 73.1 | 610.5 | 612.3 | 783.6 | 94 | ||
| 10 | J | 0.618 | 73.03 | 5.51 | 73.1 | 570.3 | 572.4 | 740.6 | 100 | ||
| 11 | K | 0.758 | 73.03 | 5.51 | 73.1 | 665.7 | 647.8 | 824.6 | 94 | ||
| 12 | L | 0.944 | 73.03 | 5.51 | 73.1 | *792.5 | 793.4 | 981.4 | 82 | ||
| 13 | M | 0.929 | 73.03 | 5.51 | 73.1 | *782.2 | 790.0 | 976.6 | 80 | ||
| 14 | N | 0.897 | 73.03 | 5.51 | 73.1 | *760.4 | 767.7 | 944.3 | 82 | ||
| 15 | O | 0.620 | 73.03 | 5.51 | 73.1 | 571.7 | 570.0 | 750.8 | 100 | ||
| 16 | A | 0.775 | 88.90 | 6.45 | 61.5 | 653.6 | 635.1 | 814.6 | 92 | ||
| 17 | B | 0.807 | 88.90 | 6.45 | 61.5 | 675.4 | 659.4 | 847.3 | 94 | ||
| 18 | C | 0.828 | 88.90 | 6.45 | 61.5 | 689.7 | 681.4 | 860.2 | 95 | ||
| 19 | D | 0.825 | 88.90 | 6.45 | 61.5 | 687.7 | 682.0 | 869.1 | 94 | ||
| 20 | E | 0.797 | 88.90 | 6.45 | 61.5 | 668.6 | 654.3 | 837.2 | 96 | ||
| 21 | F | 0.668 | 88.90 | 6.45 | 61.5 | 580.7 | 586.2 | 770.9 | 100 | ||
| 22 | G | 0.702 | 88.90 | 6.45 | 61.5 | 603.9 | 604.9 | 791.5 | 98 | ||
| 23 | H | 0.888 | 88.90 | 6.45 | 61.5 | 730.6 | 713.8 | 880.7 | 86 | ||
| 24 | I | 0.677 | 88.90 | 6.45 | 61.5 | 586.8 | 590.4 | 776.4 | 100 | ||
| 25 | J | 0.618 | 88.90 | 6.45 | 61.5 | *546.6 | 547.2 | 732.9 | 100 | ||
| 26 | K | 0.758 | 88.90 | 6.45 | 61.5 | 642.0 | 613.9 | 792.2 | 88 | ||
| 27 | L | 0.944 | 88.90 | 6.45 | 61.5 | *768.8 | 769.3 | 951.7 | 82 | ||
| 28 | M | 0.929 | 88.90 | 6.45 | 61.5 | *758.6 | 760.8 | 940.8 | 83 | ||
| 29 | N | 0.897 | 88.90 | 6.45 | 61.5 | 736.8 | 737.4 | 917.3 | 86 | ||
| 30 | O | 0.620 | 88.90 | 6.45 | 61.5 | *548.0 | 549.0 | 726.8 | 96 | ||
(remarks) * seal: beyond the scope of expression by the present invention's regulation.Roll off the production line: outside the regulation of the N80 grade of expression API specification.
Table 3
| Sample No. | The temperature of pipe before the reheat " ℃ " | The reheat temperature " ℃ " | Pipe | Tension test | The ductility fracture rate " % " of pendulum impact test | ||||||
| Chemical constitution | External diameter " mm " | Wall thickness " mm " | Sectional area degree of finish " % " | The K value | Yield strength " MPa " | Tensile strength " MPa " | |||||
| The material sequence number | The C equivalent | ||||||||||
| 31 | 350 | 810 | A | 0.775 | 139.7 | 9.17 | 30.6 | 590.6 | 581.3 | 754.6 | 93 |
| 32 | B | 0.807 | 139.7 | 9.17 | 30.6 | 612.4 | 584.6 | 770.9 | 84 | ||
| 33 | C | 0.828 | 139.7 | 9.17 | 30.6 | 626.7 | 614.2 | 802.3 | 73 | ||
| 34 | D | 0.825 | 139.7 | 9.17 | 30.6 | 624.7 | 624.3 | 804.3 | 79 | ||
| 35 | E | 0.797 | 139.7 | 9.17 | 30.6 | 605.6 | 614.2 | 786.9 | 81 | ||
| 36 | F | 0.668 | 139.7 | 9.17 | 30.6 | *517.7 | 509.4 | 690.4 | 97 | ||
| 37 | G | 0.702 | 139.7 | 9.17 | 30.6 | *540.8 | 559.3 | 723.5 | 88 | ||
| 38 | H | 0.888 | 139.7 | 9.17 | 30.6 | 667.6 | 664.1 | 838.8 | 76 | ||
| 39 | I | 0.677 | 139.7 | 9.17 | 30.6 | *523.8 | 521.5 | 695.5 | 90 | ||
| 40 | J | 0.618 | 139.7 | 9.17 | 30.6 | *483.6 | 491.1 | 669.0 | 88 | ||
| 41 | K | 0.758 | 139.7 | 9.17 | 30.6 | 579.0 | 562.3 | 738.4 | 94 | ||
| 42 | L | 0.944 | 139.7 | 9.17 | 30.6 | 705.8 | 708.4 | 886.1 | 68 | ||
| 43 | M | 0.929 | 139.7 | 9.17 | 30.6 | 695.5 | 706.2 | 873.3 | 73 | ||
| 44 | N | 0.897 | 139.7 | 9.17 | 30.6 | 673.7 | 684.3 | 849.5 | 77 | ||
| 45 | O | 0.620 | 139.7 | 9.17 | 30.6 | *485.0 | 503.8 | 670.0 | 98 | ||
| 46 | A | 0.775 | 177.80 | 10.36 | 7.7 | *543.9 | 534.9 | 698.7 | 88 | ||
| 47 | B | 0.807 | 177.80 | 10.36 | 7.7 | 565.7 | 558.8 | 725.7 | 70 | ||
| 48 | C | 0.828 | 177.80 | 10.36 | 7.7 | 580.0 | 569.7 | 756.8 | 79 | ||
| 49 | D | 0.825 | 177.80 | 10.36 | 7.7 | 577.9 | 579.4 | 754.9 | 83 | ||
| 50 | E | 0.797 | 177.80 | 10.36 | 7.7 | 558.9 | 561.3 | 726.8 | 80 | ||
| 51 | F | 0.668 | 177.80 | 10.36 | 7.7 | *470.9 | 467.9 | 637.4 | 80 | ||
| 52 | G | 0.702 | 177.80 | 10.36 | 7.7 | *494.7 | 499.8 | 669.2 | 92 | ||
| 53 | H | 0.888 | 177.80 | 10.36 | 7.7 | 620.9 | 612.5 | 786.1 | 83 | ||
| 54 | I | 0.677 | 177.80 | 10.36 | 7.7 | *477.1 | 486.4 | 650.3 | 90 | ||
| 55 | J | 0.618 | 177.80 | 10.36 | 7.7 | *436.9 | 448.9 | 624.7 | 73 | ||
| 56 | K | 0.758 | 177.80 | 10.36 | 7.7 | *532.3 | 512.1 | 689.4 | 80 | ||
| 57 | L | 0.944 | 177.80 | 10.36 | 7.7 | 659.0 | 667.7 | 816.7 | 58 | ||
| 58 | M | 0.929 | 177.80 | 10.36 | 7.7 | 648.8 | 642.7 | 817.7 | 67 | ||
| 59 | N | 0.897 | 177.80 | 10.36 | 7.7 | 627.0 | 635.8 | 818.4 | 62 | ||
| 60 | O | 0.620 | 177.80 | 10.36 | 7.7 | *438.2 | 441.5 | 614.2 | 89 | ||
(remarks)
*Seal: beyond the scope of expression by the present invention's regulation.Roll off the production line: outside the regulation of the N80 grade of expression API specification.
Table 4
| Sample No. | The temperature of pipe before the reheat " ℃ " | The reheat temperature " ℃ " | Pipe | Tension test | The ductility fracture rate " % " of pendulum impact test | ||||||
| Chemical constitution | External diameter " mm " | Wall thickness " mm " | Sectional area degree of finish " % " | The K value | Yield strength " MPa " | Tensile strength " MPa " | |||||
| The material sequence number | The C equivalent | ||||||||||
| 61 | 510 | 810 | H | 0.888 | 177.80 | 10.36 | 7.7 | 620.9 | 514.3 | 739.5 | 16 |
| 62 | 350 | 840 | H | 0.888 | 177.80 | 10.36 | 7.7 | 620.9 | 684.8 | 851.4 | 24 |
| 63 | *780 | H | 0.888 | 177.80 | 10.36 | 7.7 | 620.9 | 523.7 | 670.9 | 67 | |
| 64 | 350 | 810 | *P | 0.692 | 177.80 | 10.36 | 7.7 | *487.3 | 487.2 | 653.7 | 48 |
| 65 | *Q | 0.940 | 177.80 | 10.36 | 7.7 | 656.3 | 656.2 | 836.5 | 24 | ||
| 66 | *R | 0.727 | 177.80 | 10.36 | 7.7 | *511.2 | 511.1 | 684.7 | 36 | ||
| 67 | *S | 0.720 | 177.80 | 10.36 | 7.7 | *506.4 | 506.5 | 669.3 | 33 | ||
| 68 | *T | 0.908 | 177.80 | 10.36 | 7.7 | 634.5 | 634.2 | 810.1 | 29 | ||
| 69 | *U | 0.850 | 177.80 | 10.36 | 7.7 | 595.0 | 594.8 | 782.5 | 28 | ||
| 70 | *V | 0.918 | 177.80 | 10.36 | 7.7 | 641.3 | 641.3 | 814.6 | 24 | ||
| 71 | *W | 0.635 | 177.80 | 10.36 | 7.7 | *448.5 | 448.1 | 634.8 | 43 | ||
| 72 | *X | 0.896 | 177.80 | 10.36 | 7.7 | 626.3 | 626.6 | 803.4 | 32 | ||
(remarks)
*Seal: beyond the scope of expression by the present invention's regulation.Roll off the production line: outside the regulation of the N80 grade of expression API specification or the ductility fracture rate less than 50% of pendulum impact test.
In table 2～table 4, the chemical constitution of the pipe of test No.1～60 is in the scope of the present invention's regulation, with the pipe temperature before the reheat be made as 350 ℃, when the reheat temperature is made as 810 ℃, when the degree of finish of drawing/rolling machine satisfies the condition of above-mentioned (i) formula of the present invention's regulation (K value above 552, be lower than at 758 o'clock), yield strength and tensile strength are all in the regulation (yield strength: 552MPa～758MPa, tensile strength: more than the 724MPa) of the N80 of API specification grade.In addition, the ductility fracture rate of pendulum impact test is also very big to surpass 50%, has shown good toughness.
Test No.64～72nd, pipe temperature before the reheat and reheat temperature and above-mentioned same are set at 350 ℃, 810 ℃ respectively, but the situation of the chemical constitution of steel outside the scope of the present invention's regulation.At this moment, when satisfying above-mentioned (i) formula condition, yield strength and tensile strength enter in the regulation of N80 grade of API specification, but the ductility fracture rate of pendulum impact test is low, has the flexible problem.
Test No.61～63rd, the pipe for the chemical constitution with material numbering H changes the preceding pipe temperature of reheat and the situation of reheat temperature.The reheat temperature is set at 780 ℃ (compares A
C3The temperature that transformation temperature is low) time (test No.63), even the mode of above-mentioned to satisfy (i) formula condition is carried out 2 processing by the drawing/rolling machine, yield strength and tensile strength are also outside the regulation of the N80 of API specification grade.In addition, the pipe temperature before the reheat be 510 ℃ than higher the time (test No.61), even satisfy the condition of above-mentioned (i) formula, yield strength is also outside the regulation of the N80 of API specification grade.This think because, pack into the phase transformation to martensite, bainite etc. carried out before the reheating furnace of pipe is insufficient, can not make and organize refinement fully.
Industrial utilizability
According to the manufacture method of seamless steel pipe of the present invention, use processing and heat treatment can make efficiently also excellent oil well pipe of the regulation of intensity of the N80 grade that satisfies relevant API specification and toughness. Therefore, manufacture method of the present invention can reasonably be applied to the manufacturing of oil well seamless steel pipe.
Claims (2)
1, a kind of manufacture method of weldless steel tube is characterized in that, at the heating steel billet, after the perforation of drilling/rolling machine, implements hot rolling with mandrel mill with the sectional area degree of finish more than 30% and is processed into pipe, and this pipe is cooled to Ar
1Below the transformation temperature, then, be heated to Ac with reheating furnace
3～(Ac
3The sectional area degree of finish % that+30 ℃+employing drawing/rolling machine obtains) after the temperature range, condition with drawing/rolling machine following to satisfy (i) formula is processed, carry out air cooling then, wherein, described steel billet contains C:0.30～0.45% in quality %, below the Si:0.50%, Mn:1.0～2.0%, Cr:0.2～1.0%, V:0.02～0.20%, Nb:0.005～0.050% and below the Al:0.050%, surplus is Fe and impurity, P as impurity is below 0.05%, S is below 0.005%, Cu is below 0.05%, N is below 0.030%, O is below 0.005%, H is below 0.0005%
552＜2.04X+681.5Ceq＜758 …(i)
Here, X: the sectional area degree of finish that adopts the drawing/rolling machine to obtain, its unit is %
Ceq: with the carbon equivalent that following formula is represented, its unit is %
Ceq＝C+Mn/5+Si/7+(Cu+Cr)/9+Ni/22+V/2。
2, the manufacture method of weldless steel tube as claimed in claim 1, it is characterized in that, steel billet contains C:0.30～0.45% in quality %, below the Si:0.50%, Mn:1.0～2.0%, Cr:0.2～1.0%, V:0.02～0.20%, Nb:0.005～0.050% and below the Al:0.050%, also contain below the Ni:0.10%, during the following and Ti:0.05% of Mo:0.10% is following one or more, surplus is Fe and impurity, is below 0.05% as the P of impurity, S is below 0.005%, Cu is below 0.05%, N is below 0.030%, O is below 0.005%, H is below 0.0005%.
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| DE102010008389A1 (en) * | 2010-02-17 | 2011-08-18 | Kocks Technik GmbH & Co. KG, 40721 | Rolling system for producing seamless metallic pipe, has induction system provided between front rolling device and rear rolling device for influencing temperature of intermediate product before product is supplied to rear rolling device |
| CN102876969B (en) | 2012-07-31 | 2015-03-04 | 宝山钢铁股份有限公司 | Super-strength high-toughness wear resistant steel plate and production method thereof |
| CN114733927A (en) * | 2022-04-21 | 2022-07-12 | 山东汇通工业制造有限公司 | Seamless steel pipe for 40CrB track pin bush |
-
2006
- 2006-03-27 JP JP2006086567A patent/JP2007260705A/en active Pending
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2007
- 2007-03-26 CN CNB2007100889631A patent/CN100569982C/en not_active Expired - Fee Related
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| CN102459677A (en) * | 2009-06-24 | 2012-05-16 | 杰富意钢铁株式会社 | High-strength seamless steel tube for use in oil wells, which has excellent resistance to sulfide stress cracking and production method for same |
| CN104245168A (en) * | 2012-04-18 | 2014-12-24 | 新日铁住金株式会社 | Round billet for seamless metal tube and method for producing seamless metal tube |
| US10894278B2 (en) | 2012-04-18 | 2021-01-19 | Nippon Steel Corporation | Method for producing seamless metal tube |
| CN103741063A (en) * | 2013-12-23 | 2014-04-23 | 马鞍山市盈天钢业有限公司 | Seamless steel tube material for geological drilling and preparation method thereof |
| CN103741063B (en) * | 2013-12-23 | 2016-01-20 | 马鞍山市盈天钢业有限公司 | A kind of Seamless Steel Pipes For Geological Drilling material and preparation method thereof |
| CN109154053A (en) * | 2016-05-20 | 2019-01-04 | 新日铁住金株式会社 | Seamless steel pipe and its manufacturing method |
| CN109154053B (en) * | 2016-05-20 | 2020-08-11 | 日本制铁株式会社 | Seamless steel pipe and method for producing same |
| WO2017215479A1 (en) * | 2016-06-17 | 2017-12-21 | 浙江大学 | Method for processing high-strength and high-toughness fully-austenitic stainless steel |
| US10738372B2 (en) | 2016-06-17 | 2020-08-11 | Zhejiang University | Method of processing fully austenitic stainless steel with high strength and high toughness |
| CN107377620A (en) * | 2017-06-20 | 2017-11-24 | 衡阳华菱钢管有限公司 | Rolled seamless steel pipe and preparation method thereof |
| CN107377620B (en) * | 2017-06-20 | 2019-03-08 | 衡阳华菱钢管有限公司 | Rolled seamless steel pipe and preparation method thereof |
| CN113637890A (en) * | 2020-04-27 | 2021-11-12 | 宝山钢铁股份有限公司 | Ultra-fine grain seamless steel pipe and manufacturing method thereof |
Also Published As
| Publication number | Publication date |
|---|---|
| JP2007260705A (en) | 2007-10-11 |
| CN100569982C (en) | 2009-12-16 |
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