CN108368582A - Spool electric welded steel pipe - Google Patents
Spool electric welded steel pipe Download PDFInfo
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- CN108368582A CN108368582A CN201780004490.4A CN201780004490A CN108368582A CN 108368582 A CN108368582 A CN 108368582A CN 201780004490 A CN201780004490 A CN 201780004490A CN 108368582 A CN108368582 A CN 108368582A
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- steel pipe
- base material
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- welded steel
- electric welded
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- C—CHEMISTRY; METALLURGY
- C21—METALLURGY OF IRON
- C21D—MODIFYING THE PHYSICAL STRUCTURE OF FERROUS METALS; GENERAL DEVICES FOR HEAT TREATMENT OF FERROUS OR NON-FERROUS METALS OR ALLOYS; MAKING METAL MALLEABLE, e.g. BY DECARBURISATION OR TEMPERING
- C21D8/00—Modifying the physical properties by deformation combined with, or followed by, heat treatment
- C21D8/02—Modifying the physical properties by deformation combined with, or followed by, heat treatment during manufacturing of plates or strips
-
- C—CHEMISTRY; METALLURGY
- C21—METALLURGY OF IRON
- C21D—MODIFYING THE PHYSICAL STRUCTURE OF FERROUS METALS; GENERAL DEVICES FOR HEAT TREATMENT OF FERROUS OR NON-FERROUS METALS OR ALLOYS; MAKING METAL MALLEABLE, e.g. BY DECARBURISATION OR TEMPERING
- C21D8/00—Modifying the physical properties by deformation combined with, or followed by, heat treatment
- C21D8/02—Modifying the physical properties by deformation combined with, or followed by, heat treatment during manufacturing of plates or strips
- C21D8/0205—Modifying the physical properties by deformation combined with, or followed by, heat treatment during manufacturing of plates or strips of ferrous alloys
-
- C—CHEMISTRY; METALLURGY
- C21—METALLURGY OF IRON
- C21D—MODIFYING THE PHYSICAL STRUCTURE OF FERROUS METALS; GENERAL DEVICES FOR HEAT TREATMENT OF FERROUS OR NON-FERROUS METALS OR ALLOYS; MAKING METAL MALLEABLE, e.g. BY DECARBURISATION OR TEMPERING
- C21D8/00—Modifying the physical properties by deformation combined with, or followed by, heat treatment
- C21D8/02—Modifying the physical properties by deformation combined with, or followed by, heat treatment during manufacturing of plates or strips
- C21D8/0221—Modifying the physical properties by deformation combined with, or followed by, heat treatment during manufacturing of plates or strips characterised by the working steps
- C21D8/0226—Hot rolling
-
- C—CHEMISTRY; METALLURGY
- C21—METALLURGY OF IRON
- C21D—MODIFYING THE PHYSICAL STRUCTURE OF FERROUS METALS; GENERAL DEVICES FOR HEAT TREATMENT OF FERROUS OR NON-FERROUS METALS OR ALLOYS; MAKING METAL MALLEABLE, e.g. BY DECARBURISATION OR TEMPERING
- C21D8/00—Modifying the physical properties by deformation combined with, or followed by, heat treatment
- C21D8/10—Modifying the physical properties by deformation combined with, or followed by, heat treatment during manufacturing of tubular bodies
- C21D8/105—Modifying the physical properties by deformation combined with, or followed by, heat treatment during manufacturing of tubular bodies of ferrous alloys
-
- C—CHEMISTRY; METALLURGY
- C21—METALLURGY OF IRON
- C21D—MODIFYING THE PHYSICAL STRUCTURE OF FERROUS METALS; GENERAL DEVICES FOR HEAT TREATMENT OF FERROUS OR NON-FERROUS METALS OR ALLOYS; MAKING METAL MALLEABLE, e.g. BY DECARBURISATION OR TEMPERING
- C21D9/00—Heat treatment, e.g. annealing, hardening, quenching or tempering, adapted for particular articles; Furnaces therefor
- C21D9/08—Heat treatment, e.g. annealing, hardening, quenching or tempering, adapted for particular articles; Furnaces therefor for tubular bodies or pipes
-
- C—CHEMISTRY; METALLURGY
- C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
- C22C—ALLOYS
- C22C38/00—Ferrous alloys, e.g. steel alloys
- C22C38/001—Ferrous alloys, e.g. steel alloys containing N
-
- C—CHEMISTRY; METALLURGY
- C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
- C22C—ALLOYS
- C22C38/00—Ferrous alloys, e.g. steel alloys
- C22C38/02—Ferrous alloys, e.g. steel alloys containing silicon
-
- C—CHEMISTRY; METALLURGY
- C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
- C22C—ALLOYS
- C22C38/00—Ferrous alloys, e.g. steel alloys
- C22C38/04—Ferrous alloys, e.g. steel alloys containing manganese
-
- C—CHEMISTRY; METALLURGY
- C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
- C22C—ALLOYS
- C22C38/00—Ferrous alloys, e.g. steel alloys
- C22C38/06—Ferrous alloys, e.g. steel alloys containing aluminium
-
- C—CHEMISTRY; METALLURGY
- C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
- C22C—ALLOYS
- C22C38/00—Ferrous alloys, e.g. steel alloys
- C22C38/12—Ferrous alloys, e.g. steel alloys containing tungsten, tantalum, molybdenum, vanadium, or niobium
-
- C—CHEMISTRY; METALLURGY
- C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
- C22C—ALLOYS
- C22C38/00—Ferrous alloys, e.g. steel alloys
- C22C38/14—Ferrous alloys, e.g. steel alloys containing titanium or zirconium
-
- C—CHEMISTRY; METALLURGY
- C21—METALLURGY OF IRON
- C21D—MODIFYING THE PHYSICAL STRUCTURE OF FERROUS METALS; GENERAL DEVICES FOR HEAT TREATMENT OF FERROUS OR NON-FERROUS METALS OR ALLOYS; MAKING METAL MALLEABLE, e.g. BY DECARBURISATION OR TEMPERING
- C21D2211/00—Microstructure comprising significant phases
- C21D2211/002—Bainite
-
- C—CHEMISTRY; METALLURGY
- C21—METALLURGY OF IRON
- C21D—MODIFYING THE PHYSICAL STRUCTURE OF FERROUS METALS; GENERAL DEVICES FOR HEAT TREATMENT OF FERROUS OR NON-FERROUS METALS OR ALLOYS; MAKING METAL MALLEABLE, e.g. BY DECARBURISATION OR TEMPERING
- C21D2211/00—Microstructure comprising significant phases
- C21D2211/005—Ferrite
Abstract
The chemical composition of a kind of spool electric welded steel pipe, base material portion includes in terms of quality %：C：0.080~0.120%, Mn：0.30~1.00%, Ti：0.005~0.050%, Nb：0.010~0.100%, N：0.001~0.020%, Si：0.010~0.450% and Al：0.001~0.100%, remainder includes Fe and impurity, the CMeq shown in formula (1) is 0.170~0.300, Mn/Si ratios are 2.0 or more, the LR shown in formula (2) is 0.210 or more, in the case where observing the metal structure in base material portion using SEM with 1000 times of multiplying power, ferrite area occupation ratio is 60~98%, and remainder includes tempering bainite.CMeq=C+Mn/6+Cr/5+ (Ni+Cu)/15+Nb+Mo/3+V formulas (1) LR=(2.1 × C+Nb)/Mn formulas (2).
Description
Technical field
This application involves spool electric welded steel pipes.
Background technology
In recent years, it is being further increased mainly as the importance of the spool of one of the transportation means of crude oil or natural gas.
For the electric welded steel pipe (i.e. spool electric welded steel pipe) used as spool, the pipe for reducing electric welded steel pipe is sometimes required that
The yield ratio of axis direction.
For example, Patent Document 1 discloses a kind of technology, pass through the band before tubing shapes, to being used as raw material
Steel assigns such as cyclic strain caused by bending-rebound processing and induces Bao Xinge effects, to reduce obtained electricity
The yield ratio of the tube axial direction of Coiling Welded Pipe.
In addition, propose a kind of technology in patent document 2, by by the gold of the hot rolled steel plate of electric welded steel pipe manufacture
Belong to tissue to be made the microscopic structure that the martensite for being 1~20% by ferrite and area occupation ratio is formed, to reduce electric welded steel pipe
The yield ratio of tube axial direction.
In addition, in patent document 3, the rising of yield ratio caused by being heated by application as inhibition makes deformation characteristic carry
The manufacturing method of the excellent electric welded steel pipe of high resistant strain aging resistance, it is proposed that used Nb amounts be 0.003% less than
The manufacturing method of the electric welded steel pipe of 0.02% steel billet.In the paragraph 0019 of the patent document 3, describe " more in Nb contents
Previous electric welded steel pipe in, since the processing that is imported when tubing strains to carry out the precipitation of Nb carbide, yield strength and
Tensile strength rises.It has understood fully：In such precipitation strength, especially yield strength rises larger, as a result, yield ratio
Rise instead.”.
Patent document 1：No. 4466320 bulletins of Japanese Patent No.
Patent document 2：Japanese Unexamined Patent Publication 10-176239 bulletins
Patent document 3：International Publication No. 2012/133558
Invention content
Problems to be solved by the invention
But in the technology of patent document 1, the process due to needing to assign strain to strip, process number increases,
As a result, the manufacturing cost of electric welded steel pipe can increase sometimes.
In addition, for the technology of patent document 2, it may require that the toughness for making the base material portion of electric welded steel pipe further carries sometimes
It is high.
In addition, for the technology of patent document 3, may require that sometimes using the method other than the method for making Nb amounts reduce
To reduce the YR of electric welded steel pipe.
The project of the application is, provide be minimized with a degree of tensile strength and yield strength, yield ratio,
The spool electric welded steel pipe of the excellent tenacity of base material portion and resistance weld.
Means for solving the problems
Means for solving the problem includes scheme below.
<1>A kind of spool electric welded steel pipe, it includes base material portion and resistance weld,
The chemical composition in the base material portion includes in terms of quality %：
C：0.080~0.120%,
Mn：0.30~1.00%,
Ti：0.005~0.050%,
Nb：0.010~0.100%,
N：0.001~0.020%,
Si：0.010~0.450%,
Al：0.001~0.100%,
P：0~0.030%,
S：0~0.0100%,
Mo：0~0.50%,
Cu：0~1.00%,
Ni：0~1.00%,
Cr：0~1.00%,
V：0~0.100%,
Ca：0~0.0100%,
Mg：0~0.0100%,
REM：0~0.0100% and
Remainder：Fe and impurity,
Wherein, the CMeq shown in following formula (1) is 0.170~0.300,
The ratio between the quality % of the quality % of Mn relative to Si are 2.0 or more,
The LR shown in following formula (2) is 0.210 or more,
In the case where observing the metal structure in the base material portion using scanning electron microscope with 1000 times of multiplying power,
The area occupation ratio of the first phase formed by ferrite is 60~98%, and the second phase as remainder includes tempering bainite,
The yield strength of tube axial direction is 390~562MPa,
The tensile strength of tube axial direction is 520~690MPa,
The yield ratio of tube axial direction be 90% hereinafter,
The Charpy impact absorption of the pipe circumferential direction in the base material portion can be 100J or more at 0 DEG C,
The Charpy impact absorption of the pipe circumferential direction of the resistance weld can be 80J or more at 0 DEG C.
CMeq=C+Mn/6+Cr/5+ (Ni+Cu)/15+Nb+Mo/3+V formulas (1)
LR=(2.1 × C+Nb)/Mn formulas (2)
(in formula (1) and formula (2), C, Mn, Cr, Ni, Cu, Nb, Mo and V indicate the quality % of each element respectively.〕
<2>According to<1>The spool electric welded steel pipe, wherein the chemical composition in the base material portion is contained in terms of quality %
Have：
Mo：More than 0% and for 0.50% or less,
Cu：More than 0% and for 1.00% or less,
Ni：More than 0% and for 1.00% or less,
Cr：More than 0% and for 1.00% or less,
V：More than 0% and for 0.100% or less,
Ca：More than 0% and for 0.0100% or less,
Mg：More than 0% and for 0.0100% or less and
REM：More than 0% and it is 0.0100% or less
In it is one kind or two or more.
<3>According to<1>Or<2>The spool electric welded steel pipe, wherein using transmission electron microscope with
In the case that 100000 times of multiplying power observes the metal structure in the base material portion, equivalent circle diameter is 100nm precipitates below
Area occupation ratio be 0.10~1.00%.
<4>According to<1>~<3>Any one of described in spool electric welded steel pipe, wherein the chemical composition in the base material portion
In the content of Nb be calculated as 0.020% or more with quality %.
<5>According to<1>~<4>Any one of described in spool electric welded steel pipe, wall thickness is 10~25mm, and outer diameter is
114.3~609.6mm.
Invention effect
According to the application, it is possible to provide have a degree of tensile strength and yield strength, yield ratio be minimized, base material
The spool electric welded steel pipe of the excellent tenacity of portion and resistance weld.
Description of the drawings
Fig. 1 is the scanning electron microscope photo of an example of the metal structure for indicating the base material portion in the application.
Specific implementation mode
In this specification, it refers to including the front and back recorded numerical value of "~" and making to use the numberical range represented by "~"
For lower limiting value and the range of upper limit value.
In this specification, " % " of the content of expression composition (element) refers to " quality % ".
In this specification, the content of C (carbon) is recorded as " C amounts " sometimes.Sometimes for the content of other elements also into
Row is same to be recorded.
In this specification, " process " this term not only include independent process, even if can not with other processes into
In the case that row is clearly distinguished, as long as reaching the desired purpose of the process, then it is also contained in this term.
The spool of the application includes base material portion and resistance weld with electric welded steel pipe (hereinafter also referred to as " electric welded steel pipe "),
The chemical composition in base material portion includes in terms of quality %：C：0.080~0.120%, Mn：0.30~1.00%, Ti：0.005~
0.050%, Nb：0.010~0.100%, N：0.001~0.020%, Si：0.010~0.450%, Al：0.001~
0.100%, P：0~0.030%, S：0~0.0100%, Mo：0~0.50%, Cu：0~1.00%, Ni：0~1.00%, Cr：
0~1.00%, V：0~0.100%, Ca：0~0.0100%, Mg：0~0.0100%, REM：0~0.0100% and remaining
Part：Fe and impurity, wherein the CMeq shown in following formula (1) is matter of the quality % of 0.170~0.300, Mn relative to Si
It is 2.0 or more to measure the ratio between % (hereinafter also referred to " Mn/Si ratios "), and the LR shown in following formula (2) is 0.210 or more, is being used
In the case that scanning electron microscope is with the metal structure in 1000 times of multiplying power observation base material portion, formed by ferrite first
The area occupation ratio (hereinafter also referred to " ferrite divides rate ") of phase is 60~98%, and the second phase as remainder includes tempering bayesian
The yield strength (hereinafter also referred to " YS ") of body, tube axial direction is 390~562MPa, and the tensile strength of tube axial direction is (below
Referred to as " TS ") be 520~690MPa, the yield ratio (hereinafter also referred to " YR ") of tube axial direction be 90% hereinafter, base material portion pipe
The Charpy impact absorption of circumferential direction can be 100J or more at 0 DEG C, and the Charpy impact absorption of the pipe circumferential direction of resistance weld can be 0
DEG C be 80J or more.
CMeq=C+Mn/6+Cr/5+ (Ni+Cu)/15+Nb+Mo/3+V formulas (1)
LR=(2.1 × C+Nb)/Mn formulas (2)
(in formula (1) and formula (2), C, Mn, Cr, Ni, Cu, Nb, Mo and V indicate the quality % of each element respectively.〕
The electric welded steel pipe of the application includes base material portion and resistance weld.
What electric welded steel pipe was manufactured generally by following methods：It is (following to be also referred to as by the way that hot rolled steel plate is configured to tubulose
For " roll forming ") open tube is made, the docking section of obtained open tube is resistance welded and forms resistance welding
Portion (electric resistance welded portion) then as needed, carries out at weld seam heat resistance weld
Reason.
In the electric welded steel pipe of the application, so-called base material portion (base metal portion) refers in addition to resistance weld
With the part other than heat affected zone.
Wherein, so-called heat affected zone (heat affected zone；Hereinafter also referred to " HAZ ") refer to by by electric resistance welding
The influence of heat caused by connecing (is then by resistance welding and weld seam heat in the case of carrying out weld seam heat treatment after resistance welding
Processing caused by heat influence) part.
In the present specification, resistance weld is referred to as " weld part " sometimes.
The electric welded steel pipe of the application has a degree of YS and TS (that is, YS and TS of above-mentioned range), and YR is lowered
To 90% hereinafter, the excellent tenacity of base material portion and resistance weld.
In this application, so-called excellent tenacity refer to 0 DEG C of pipe circumferential direction Charpy impact absorb can (J) (below
Referred to as " vE ") it is big.
Specifically, the vE in the base material portion of the electric welded steel pipe of the application is 100J or more, the vE of resistance weld be 80J with
On.
The electric welded steel pipe of the application is since YR is low, it is therefore contemplated that can inhibit the effect of electric welded steel pipe buckled.
As requiring to inhibit the phenomenon that the example that steel pipe is buckled, it can enumerate and the steel pipe of seabed spool is passed through into volume
Cylinder (Reeling) is laid with come the case where laying.For reel laying, steel pipe is manufactured in land in advance, will be manufactured
Steel pipe be wound up on the spool of barge.The steel pipe being wound is routed to seabed while at sea unreeling.The reel is spread
If assigning plastic bending to steel pipe when being unreeled due to that can also have in the winding of steel pipe, it is therefore possible to so that steel pipe is buckled.
In case of buckling for steel pipe, if it has to stop being laid with operation, damage is huge.
Buckling for steel pipe can be inhibited by reducing the YR of steel pipe.
Therefore, according to the electric welded steel pipe of the application, such as it can be expected that following such effects：It can inhibit as submarine cable
Effective electric welded steel pipe carrys out the buckling when reel in the case of use is laid with.
In addition, the electric welded steel pipe of the application is due to base material portion and the excellent tenacity of resistance weld, it can be expected that following
Such effect：As spool with electric welded steel pipe come rupture in the case of use when crevasse crack propagation stop performance it is excellent.
Above-mentioned YS, TS, YR, the vE in base material portion and resistance weld vE pass through the above-mentioned chemical composition in electric welded steel pipe
The combination of (including CMeq, Mn/Si when LR) and above-mentioned metal structure is reached.
(chemical composition in base material portion)
Hereinafter, the chemical composition about base material portion first illustrates each ingredient in chemical composition, it is then, right
When LR is illustrated by CMeq, Mn/Si.
C：0.080~0.120%
C is to form the element needed for the second phase.
If C amounts are 0.080% or more, it is easy to reach 98% ferrite point rate below, in addition, being easy to reach
0.210 or more LR.As a result, being easy to reach 90% YR below.Therefore, C amounts are 0.080% or more.C amounts are preferably
0.085% or more.
On the other hand, if C amounts be 0.120% hereinafter, if be easy to reach 60% or more ferrite point rate.Its result
It is to be easy to reach 90% YR below.Therefore, the C amounts in the application are 0.120% or less.C amounts be preferably 0.115% hereinafter,
More preferably 0.110% or less.
Mn：0.30~1.00%
Mn is the element for the quenching degree for improving steel.In addition, innoxious required elements of the Mn also for S.
If Mn amounts are less than 0.30%, will produce brittle caused by S, it is possible to the toughness of base material and resistance weld
It can deteriorate.Therefore, Mn amounts are 0.30% or more.Mn amounts are preferably 0.40% or more, more preferably 0.50% or more.
On the other hand, if Mn amounts are more than 1.00%, coarse MnS can be generated in the central portion of plate thickness, it is possible to meeting
Damage the toughness of base material and resistance weld.In addition, if Mn amounts are more than 1.00%, it is likely that 0.210 or more can not be reached
LR, as a result, it is possible to 90% YR below can not be reached.Therefore, Mn amounts are 1.00% or less.Mn amounts are preferably
0.90% hereinafter, more preferably 0.85% or less.
Ti：0.005~0.050%
Ti is the element to form carbonitride, contribute to crystal particle diameter miniaturization.
From the viewpoint of ensuring the toughness of base material and resistance weld, Ti amounts are 0.005% or more.
On the other hand, if Ti amounts are more than 0.050%, coarse TiN can be generated, it is possible to base material and resistance weld
Toughness can deteriorate.Therefore, Ti amounts are 0.050% or less.Ti amounts be preferably 0.040% hereinafter, further preferably 0.030 with
Under, particularly preferably 0.025%.
Nb：0.010~0.100%
The element that Nb contributes to the raising of toughness and YR is reduced.
It is improved to roll caused toughness by non-recrystallization, Nb amounts are 0.010% or more.Nb amounts are preferably
0.020% or more.
On the other hand, if Nb amounts are more than 0.100%, toughness is caused to deteriorate due to coarse carbide.Therefore, Nb amounts
It is 0.100% or less.Nb amounts are preferably 0.090% or less.
N：0.001~0.020%
N is to inhibit the coarsening of crystal grain, its result to make the tough of base material portion and resistance weld by forming nitride
Property improve element.From the viewpoint of such effect, N amounts are 0.001% or more.N amounts are preferably 0.003% or more.
On the other hand, if N amounts are more than 0.020%, the production quantity of alloy carbide increases, base material portion and resistance welding
The toughness in portion can deteriorate.Therefore, N amounts are 0.020% or less.N amounts be preferably 0.015% hereinafter, more preferably 0.010% with
Under, particularly preferably 0.008% or less.
Si：0.010~0.450%
Si is the element functioned as the deoxidier of steel.More specifically, if Si amounts are 0.010% or more,
It can inhibit and generate coarse oxide in base material portion and resistance weld, as a result, the toughness of base material portion and resistance weld
It improves.Therefore, Si amounts are 0.010% or more.Si amounts are preferably 0.015% or more, more preferably 0.020% or more.
On the other hand, if Si amounts are more than 0.450%, field trash can be generated in resistance weld, it is possible to which Charpy is rushed
Hit absorption can reduce and toughness deterioration.Therefore, Si amounts are 0.450% or less.Si amounts are preferably 0.400% hereinafter, more preferably
0.350% hereinafter, particularly preferably 0.300% or less.
Al：0.001~0.100%
Al same as Si is the element functioned as deoxidier.More specifically, if Al amounts be 0.001% with
On, then it can inhibit and generate coarse oxide in base material portion and resistance weld, as a result, base material portion and resistance weld
Toughness improves.Therefore, Al amounts are 0.001% or more.Al amounts are preferably 0.010% or more, more preferably 0.015% or more.
On the other hand, if Al amounts are more than 0.100%, it is likely that the life of Al systems oxide when along with resistance welding
At and toughness of welded zone deteriorates.Therefore, Al amounts are 0.100% or less.Al amounts are preferably 0.090% or less.
P：0~0.030%
P is impurity element.If P amounts are more than 0.030%, it is likely that can be damaged tough since segregation occurs in crystal boundary
Property.Therefore, P amounts are 0.030% or less.P amounts be preferably 0.025% hereinafter, more preferably 0.020% hereinafter, further preferably
For 0.015% hereinafter, more preferably 0.010% or less.
P amounts or 0%.From the viewpoint of reducing dephosphorization cost, P amounts can also be more than 0%, or
0.001% or more.
S：0~0.0100%
S is impurity element.If S amounts are more than 0.0100%, it is likely that toughness can be damaged.Therefore, S amounts are 0.0100%
Below.S amounts are preferably 0.0070% hereinafter, more preferably 0.0050% hereinafter, more preferably 0.0030% or less.
S amounts or 0%.From the viewpoint of reducing desulphurization cost, S amounts can also be more than 0%, or
0.0001% or more, or 0.0003% or more.
Mo：0~0.50%
Mo is optional element.Therefore, Mo amounts or 0%.
Mo is the element for improving the quenching degree of steel, contributing to the high intensity of steel.From the viewpoint of such effect,
Mo amounts can also be more than 0%, or 0.01% or more, or 0.03% or more.
On the other hand, if Mo amounts are more than 0.50%, it is likely that so that toughness is reduced due to the generation of Mo carbonitrides.
Therefore, Mo amounts are 0.50% or less.Mo amounts be preferably 0.40% hereinafter, more preferably 0.30% hereinafter, further preferably
0.20% hereinafter, particularly preferably 0.10% or less.
Cu：0~1.00%
Cu is optional element.Therefore, Cu amounts or 0%.
Cu is to improve effective element to the intensity of base material.From the viewpoint of such effect, Cu amounts can also be more than
0%, or 0.01% or more, or 0.03% or more.
On the other hand, if Cu amounts are more than 1.00%, it is likely that generate fine Cu particles, toughness is made significantly to deteriorate.
Therefore, Cu amounts are 1.00% or less.Cu amounts be preferably 0.80% hereinafter, more preferably 0.70% hereinafter, further preferably
0.60% hereinafter, particularly preferably 0.50% or less.
Ni：0~1.00%
Ni is optional element.Therefore, Ni amounts or 0%.
Ni contributes to the element of the raising of intensity and toughness.From the viewpoint of such effect, Ni amounts can also surpass
Cross 0%, or 0.01% or more, or 0.05% or more.
On the other hand, if Ni amounts are more than 1.00%, it is likely that intensity becomes excessively high.Therefore, Ni amounts be 1.00% with
Under.Ni amounts are preferably 0.80% hereinafter, more preferably 0.70% hereinafter, further preferably 0.60% or less.
Cr：0~1.00%
Cr is optional element.Therefore, Cr amounts or 0%.
Cr is the element for improving quenching degree.From the viewpoint of such effect, Cr amounts can also be more than 0%, can also
It is 0.01% or more, or 0.05% or more.
On the other hand, if Cr amounts are more than 1.00%, it is likely that due to the Cr systems field trash generated in resistance weld
And the toughness of weld part is caused to deteriorate.Therefore, Cr amounts are 1.00% or less.Cr amounts are preferably 0.80% hereinafter, more preferably
0.70% hereinafter, further preferably 0.50% hereinafter, particularly preferably 0.30% or less.
V：0~0.100%
V is optional element.Therefore, V amounts or 0%.
The element that V contributes to the raising of toughness and YR is reduced.From the viewpoint of such effect, V amounts can also surpass
Cross 0%, or 0.005% or more, or 0.010% or more.
On the other hand, if V amounts are more than 0.100%, it is likely that cause toughness to deteriorate due to V carbonitrides.Therefore,
V amounts are 0.100% or less.V amounts are preferably 0.080% hereinafter, more preferably 0.070% hereinafter, further preferably 0.050%
Hereinafter, particularly preferably 0.030% or less.
Ca：0~0.0100%
Ca is optional element.Therefore, Ca amounts or 0%.
Ca is the form for controlling sulfide-based field trash, makes the element of low-temperature flexibility raising.From the viewpoint of such effect
It sets out, Ca amounts can also be more than 0%, or 0.0001% or more, or 0.0010% or more, or
0.0030% or more, or 0.0050% or more.
On the other hand, if Ca amounts are more than 0.0100%, it is likely that generate by the CaO-CaS large-scale clusters formed or greatly
The field trash of type causes harmful effect to toughness.Therefore, Ca amounts are 0.0100% or less.Ca amounts be preferably 0.0090% hereinafter,
More preferably 0.0080% hereinafter, particularly preferably 0.0060% or less.
Mg：0~0.0100%
Mg is optional element.Therefore, Mg amounts or 0%.
Mg is especially to will produce fine oxide as deoxidier and the effective element of desulfurizing agent, also contribute to HAZ
The element of the raising of the toughness of (Heat affected zone).From the viewpoint of such effect, Mg amounts can also be more than
0%, or 0.0001% or more, or 0.0010% or more, or 0.0020% or more, or
0.0030% or more, or 0.0050% or more.
On the other hand, if Mg amounts are more than 0.0100%, oxide becomes easy cohesion or coarsening, as a result,
Be likely to result in Resistant to HIC (resistance against hydrogen cracking, Hydrogen-Induced Cracking Resistance) reduction or
The reduction of the toughness of base material or HAZ.Therefore, Mg amounts are 0.0100% or less.Mg amounts are preferably 0.0060% or less.
REM：0~0.0100%
REM is optional element.Therefore, REM amounts or 0%.
Wherein, " REM " refer to rare earth element i.e. be selected from Sc, Y, La, Ce, Pr, Nd, Pm, Sm, Eu, Gd, Tb, Dy, Ho,
At least one kind of element in Er, Tm, Yb and Lu.
REM is as deoxidier and the effective element of desulfurizing agent.From the viewpoint of such effect, REM amounts can also
More than 0%, or 0.0001% or more, or 0.0010% or more.
On the other hand, if REM amounts are more than 0.0100%, coarse oxide is generated, as a result, being likely to result in
The reduction of the toughness of the reduction of Resistant to HIC or base material or HAZ.Therefore, REM amounts are 0.0100% or less.REM amounts are preferably
0.0070% hereinafter, more preferably 0.0050% or less.
From the viewpoint of obtaining the effect caused by above-mentioned optional element, the chemical composition in base material portion can also
Contain：Mo：More than 0% and it is 0.50% or less, Cu：More than 0% and it is 1.00% or less, Ni：More than 0% and for 1.00% with
Under, Cr：More than 0% and it is 1.00% or less, V：More than 0% and it is 0.100% or less, Ca：More than 0% and for 0.0100% with
Under, Mg：More than 0% and it is 0.0100% or less and REM：It is one kind or two or more more than 0% and in being 0.0100% or less.
For the preferred amount of each optional element, each as described above.
Remainder：Fe and impurity
In the chemical composition in base material portion, the remainder other than above-mentioned each element is Fe and impurity.
Wherein, so-called impurity refers to the either mixed ingredient in the process of manufacture of the ingredient contained in raw material,
Rather than intentionally make the ingredient contained in steel.
As impurity, all elements other than above-mentioned element can be enumerated.Element as impurity can be only 1
Kind, or two or more.
As impurity, such as O, B, Sb, Sn, W, Co, As, Pb, Bi, H can be enumerated.
In above-mentioned element, O preferably reaches 0.006% mode below according to content and is controlled.
In addition, for other elements, it usually can be as follows respectively：It is 0.1% to have content for Sb, Sn, W, Co and As
It is below that be mixed into, have content for Pb and Bi be 0.005% below to be mixed into, have content to be 0.0003% below mixed for B
Enter, have for H content be 0.0004% it is below be mixed into, for the content of other elements, as long as common range, then not
It needs especially to be controlled.
CMeq：0.170~0.300
In the chemical composition in base material portion, the CMeq shown in following formula (1) is 0.170~0.300.
CMeq=C+Mn/6+Cr/5+ (Ni+Cu)/15+Nb+Mo/3+V formulas (1)
(in formula (1), C, Mn, Cr, Ni, Cu, Nb, Mo and V indicate the quality % of each element respectively.〕
CMeq has positive correlation relative to yield strength.
From the viewpoint of being easy to reach yield strength and being 390MPa or more, CMeq is 0.170 or more.CMeq is preferably
0.180 or more, more preferably 0.200 or more, further preferably 0.230 or more.
On the other hand, from the viewpoint of being easy to reach yield strength and being 562MPa or less, CMeq is 0.300 or less.
CMeq is preferably 0.290 hereinafter, more preferably 0.275 or less.
LR：0.210 or more
In the chemical composition in base material portion, the LR shown in following formula (2) is 0.210 or more.
It is 0.210 or more by LR for the electric welded steel pipe of the application, is 90% or less to may achieve YR.
In the case where LR is less than 0.210, it is possible to which YR can be more than 90%.Its reason be presently considered to be because：Analysis in steel
Go out object amount to tail off, work hardening capacity reduces (i.e. TS reductions).
LR=(2.1 × C+Nb)/Mn formulas (2)
(in formula (2), C, Nb and Mn indicate the quality % of each element respectively.〕
The technical meaning of formula (2) is as follows.
In formula (2), the reasons why C amounts and Nb amounts are configured at molecule be because it is believed that：It is formed and is precipitated by C and Nb
Object, and the work hardening capacity of steel is made to improve (i.e. TS risings), as a result, the YR of steel is reduced.
C amounts be multiplied by the reasons why " 2.1 " be because it is believed that：Caused processing hardening is formed about by above-mentioned precipitate
The effect that ability improves is about 2.1 containing caused effect times by Nb by the caused effect that contains of C.
In formula (2), the reasons why Mn amounts are configured at denominator be because：Although can by containing for Mn make steel than
Phase transformation at lower temperature, but lead to the work hardening capacity damaged themselves (i.e. TS reductions) of steel due to containing for Mn,
As a result, the YR of steel rises.
As described above, LR has positive correlation relative to Nb amounts and C measurers, there is negative correlation relative to Mn measurers.
It is 0.210 or more by meeting LR, even to more in Nb amounts for the electric welded steel pipe of the application
In the case of, for example than in patent document 3 (International Publication No. 2012/133558) Nb amounts (0.003% less than
0.02%) in the case of more, it is also possible to so that LR is reached 0.210 or more by C amounts and Mn amounts.In this case, reachable
It is 90% or less at YR.
In addition, for the electric welded steel pipe of the application, even in the case where Nb amounts are less than 0.02%, by meeting LR
For the condition other than 0.210 or more and LR, also may achieve YR is 90% or less.
From the viewpoint of be more easily achieved YR be 90% or less, LR is preferably 0.230 or more, more preferably 0.270 with
On.
The upper limit of LR is not particularly limited.From the viewpoint of the manufacture adaptability of electric welded steel pipe, LR is preferably
0.500 hereinafter, more preferably 0.450 hereinafter, particularly preferably 0.400 or less.
Mn/Si ratios：More than 2.0
In the chemical composition in base material portion, Mn/Si ratios (i.e. the ratio between the quality % of the quality % of Mn relative to Si Mn/Si ratios)
It is 2.0 or more.
It is 2.0 or more by Mn/Si ratios so that the toughness of resistance weld is able to for the electric welded steel pipe of the application
It improves, the vE (absorbing energy in the Charpy impact of 0 DEG C of pipe circumferential direction) of resistance weld reaches 80J or more.
In the case where Mn/Si ratios are less than 2.0, it is possible to which vE can get lower than 80J.Its reason be presently considered to be because：
In the case that Mn/Si ratios are less than 2.0, cause since the field trash of MnSi systems becomes the starting point of brittle fracture in resistance weld
Toughness deteriorates.
From the viewpoint of the toughness for further increasing resistance weld, Mn/Si ratios are preferably 2.1 or more.
For Mn/Si than the upper limit be not particularly limited.From the toughness and base material portion for further increasing resistance weld
From the perspective of toughness, Mn/Si ratios are preferably 50 hereinafter, more preferably 40 hereinafter, particularly preferably 30 or less.
(metal structure in base material portion)
In the electric welded steel pipe of the application, the metal structure in base material portion using scanning electron microscope with 1000 times
In the case that multiplying power observes the metal structure, ferrite divide rate (area occupation ratio of the first phase formed by ferrite) be 60~
98%, the second phase as remainder is at least one of tempering bainite and pearlite.
For the electric welded steel pipe of the application, rate is divided to be 60% or more by ferrite, may achieve YR is 90% or less.Iron
Ferritic point rate is preferably 65% or more, and more preferably 70% or more.
In addition, for the electric welded steel pipe of the application, as described above, by ferrite point rate for 98% hereinafter, may achieve
TS is 520MPa or more.Ferrite point rate is preferably 95% hereinafter, more preferably 92% or less.
In the electric welded steel pipe of the application, the second phase as remainder includes tempering bainite.
Second phase include tempering bainite refer to the application electric welded steel pipe be after tubing (i.e. after resistance welding (
After being heat-treated for weld seam in the case of implementing weld seam heat treatment after resistance welding)) it has been carried out the electric welded steel pipe of tempering.
Electric welded steel pipe by the application be carried out after tubing tempering electric welded steel pipe, may achieve YR be 90% with
Under.Its reason be presently considered to be because：YR is set to decline by tempering after tubing.Tempering after tubing by, makes YR decline
Reason be presently considered to be because：Reduced by dislocation density by YS made to decline, and make by the way that cementite is being precipitated in dislocation plus
Work hardening becomes larger (i.e. TS risings).
In the present specification, tempering bainite by its tissue in comprising granular cementite this point and be not tempering
The bainite of bainite distinguishes.
Include in the concept of " bainite " in this specification：Bainite ferrite, granular bainite, upper bainite and under
Bainite.
As long as the second phase can be the phase for only including tempering bainite, can also include back including tempering bainite
Tissue other than fiery bainite.
As the tissue other than tempering bainite, pearlite can be enumerated.
It also include pseudopearlite in the concept of " pearlite " in this specification.
In the metal structure in base material portion, the measurement of ferrite point rate and the specific of the second phase are by progress of such as getting off
's：Wall thickness to the L section parts of 90 ° of positions of base material is that the metal structure of 1/4 position carries out nitric acid ethyl alcohol etching, uses sweep type
Electron microscope (SEM) is with the photo (hereinafter also referred to " gold of the metal structure after 1000 times of multiplying power observation nitric acid ethyl alcohol etching
Belong to macrograph ").Wherein, metal structure photo carries out 10 visual field amounts (in terms of the real area of section by 1000 times of visual field
For 0.12mm2Amount) shooting.By the metal structure photo of shooting is subjected to image procossing carry out ferrite point rate measurement and
Second phase it is specific.Image procossing uses the Small Universal image analysis apparatus LUZEX of such as Nireco Corporation
AP is carried out.
In the present specification, so-called " 90 ° of positions of base material " refer to the position for deviateing 90 ° from resistance weld to pipe circumferential direction
Set, so-called " L sections " refers to the section parallel relative to tube axial direction and wall thickness direction, so-called " 1/4 position of wall thickness " refer to
The distance of the peripheral surface of electric welded steel pipe is 1/4 position of wall thickness.
In addition, in the present specification, tube axial direction is known as in " directions L " sometimes.
Fig. 1 is the scanning electron microscope photo of an example of the metal structure for indicating the base material portion in the application
(SEM photograph；Multiplying power is 1000 times).
The SEM photograph of Fig. 1 be in aftermentioned embodiment 17 for ferrite point rate measurement and the second phase it is specific
One (1 visual field) in SEM photograph.
As shown in Figure 1, the first phase formed by ferrite and second comprising tempering bainite can be confirmed
Phase.Especially from there is the point (cementite) of white：Second phase includes tempering bainite.
The metal structure in base material portion is observing the metal structure using transmission electron microscope with 100000 times of multiplying power
In the case of, equivalent circle diameter be 100nm precipitates below (hereinafter also referred to " specific precipitate ") area occupation ratio (below
Referred to as " specific precipitate area occupation ratio ") it is preferably 0.10~1.00%.
If specific precipitate area occupation ratio is 0.10% or more, it is 90% or less that YR, which is more easily achieved,.Its reason evidence is recognized
To be because：Specific precipitate (i.e. equivalent circle diameter is 100nm precipitates below) contributes to the raising of Work Hardening Characteristic
(i.e. the rising of TS), as a result, YR is reduced.
On the other hand, if specific precipitate area occupation ratio be 1.00% hereinafter, if brittle fracture be able to inhibit (i.e. base material portion
Excellent tenacity).Specific precipitate area occupation ratio is preferably 0.80% hereinafter, more preferably 0.70% or less.
Specific precipitate area occupation ratio can pass through the temperature of the progress 400 DEG C~Ac1 points after tubing for 0.10~1.00%
Under tempering reach.
In this application, precipitate area occupation ratio (i.e. equivalent circle diameter be 100nm precipitates below area occupation ratio) can be with
It is with the wall thickness of the L section parts of 100000 times 90 ° of positions of multiplying power observation base material by using transmission electron microscope (TEM)
The metal structure of 1/4 position is measured.
More specifically, first, the wall thickness based on the L section parts from 90 ° of positions of base material is the sample of 1/4 station acquisition,
By using the electrolyte made of 10 volume % acetylacetone,2,4-pentanediones, 1 volume % tetramethyl ammonium chlorides and 89 volume % methanol
SPEED methods make tem observation duplicate.By using TEM with 100000 times obtained tem observation duplicate
Multiplying power is observed, to the TEM image of 1 μm of cubic field size of 10 visual field amounts of acquirement.Calculating equivalent circle diameter is
Area occupation ratio of the 100nm precipitates below relative to the gross area of acquired TEM image, using obtained result as specific
Precipitate area occupation ratio (%).
In addition, the condition of the etching in above-mentioned SPEED methods is set as following conditions：Using saturated calomel electrode as reference
Electrode, relative to about 80 square millimeters of surface areas with the charge of 10 coulombs of the voltage application of -200mV.
In addition, specific precipitate (i.e. equivalent circle diameter is 100nm precipitates below) is specifically presently considered to be and is selected from
The carbonitride of the carbide of metal other than Fe, the nitride of the metal other than Fe and the metal other than Fe
In it is at least one kind of.
As the metal described herein other than Fe, it is believed that be Ti and Nb.In addition, containing V, Mo in chemical composition
And in the case of at least one kind of in Cr, as the above-mentioned metal other than Fe, be considered as in V, Mo and the Cr at least 1
Kind.
(yield strength (YS) of tube axial direction)
The yield strength (YS) of the tube axial direction of the electric welded steel pipe of the application is 390~562MPa.
The YS of tube axial direction is preferably 430MPa or more, more preferably 450MPa or more, more preferably 470MPa or more, special
It You Xuanwei not 500MPa or more.
The YS of tube axial direction is preferably 550MPa hereinafter, more preferably 540MPa is hereinafter, particularly preferably 530MPa or less.
The YS of tube axial direction can be reached for 562MPa or less by being tempered after tubing.Its reason be presently considered to be because
For：Tempering after tubing by, makes tubing strain be mitigated, and dislocation density declines.
(tensile strength (TS) of tube axial direction)
The tensile strength (TS) of the tube axial direction of the electric welded steel pipe of the application is 520~690MPa.
The TS of tube axial direction is preferably 550MPa or more, more preferably 580MPa or more.
The TS of tube axial direction is preferably 680MPa hereinafter, more preferably 660MPa is hereinafter, particularly preferably 650MPa or less.
(yield ratio of tube axial direction)
The yield ratio (YR=(YS/TS) × 100) of the tube axial direction of the electric welded steel pipe of the application is 90% or less.
Electric welded steel pipe when can inhibit laying as a result, etc. is buckled.
The YR of tube axial direction can be reached for 90% or less by being tempered after tubing.Its reason be presently considered to be because
For：It is reduced by dislocation density by YS is made to decline, and be imperceptibly precipitated in dislocation by cementite by processing hardening is made to become
(i.e. TS risings) greatly.
(wall thickness of electric welded steel pipe)
The wall thickness of the electric welded steel pipe of the application is preferably 10~25mm.
If wall thickness be 10mm or more, using hot rolled steel plate is configured to tubulose when strain and so that YR is easily reduced
It is advantageous on this aspect.Wall thickness is more preferably 12mm or more.
If wall thickness be 25mm hereinafter, if in the manufacture adaptability of electric welded steel pipe (be specifically, to shape hot rolled steel plate
For tubulose when formability) be advantageous on this aspect.Wall thickness is more preferably 20mm or less.
(shape of electric welded steel pipe)
The outer diameter of the electric welded steel pipe of the application is preferably 114.3~609.6mm (i.e. 4.5~24 inches).
If outer diameter is 114.3mm or more, it is more suitable for electric welded steel pipe as spool.Outer diameter be preferably 139.7mm (i.e.
5.5 inches) more than, more preferably 177.8mm (i.e. 7 inches) or more.
If outer diameter for 609.6mm hereinafter, if using hot rolled steel plate is configured to tubulose when strain so that YR is easy
It reduces and is advantageous on this aspect.Outer diameter is preferably 406.4mm (i.e. 16 inches) hereinafter, more preferably 304.8mm (i.e. 12 inches)
Below.
(example of preparation method)
One example of the preparation method of the electric welded steel pipe as the application, can enumerate preparation method A below.
Preparation method A has following processes：
The work of as-rolled condition (as-roll) electric welded steel pipe is manufactured using the hot rolled steel plate with above-mentioned chemical composition
Sequence and
The tempering process of electric welded steel pipe is obtained by implementing tempering to as-rolled condition electric welded steel pipe.
According to above-mentioned preparation method A, by the way that with tempering process, based on above-mentioned reason, and easy to manufacture YR is 90% or less
Electric welded steel pipe.
Temperature (the holding temperature in being tempered) is preferably 400 DEG C~Ac1 points.
If temperature is 400 DEG C or more, being easier to make cementite and specific precipitate, (equivalent circle diameter is
100nm precipitates below) it is precipitated, therefore it is 90% or less that YR, which is more easily achieved,.As temperature, more preferably 420 DEG C
More than.
If temperature be Ac1 points hereinafter, if can further suppress precipitate and become thick.Although temperature
It is different because of the Ac1 of steel points, but preferably also 720 DEG C hereinafter, preferably also 710 DEG C hereinafter, preferably also 700 DEG C or less.
Here, when Ac1 points are the temperature rises for instigating steel, start the temperature to austenite phase transformation.
Ac1 points are calculated by following formula.
Ac1 points (DEG C)=750.8-26.6C+17.6Si-11.6Mn-22.9Cu-23Ni+24.1Cr+22.5Mo-39.7 V-
5.7Ti+232.4Nb-169.4Al
(wherein, C, Si, Mn, Ni, Cu, Cr, Mo, V, Ti, Nb and Al are respectively the quality % of each element.Ni、Cu、Cr、Mo
And V is optional element, in terms of, not by containing the element in steel billet, being come by 0 mass % in these optional elements
Calculate Ac1 points.〕
It is being easier that YR is made to reduce on this aspect, the tempering time (retention time i.e. in temperature) in tempering process is excellent
It is selected as 5 minutes or more.
In preparation method A, so-called as-rolled condition electric welded steel pipe refer to by hot rolled steel plate carry out roll forming (i.e. tubulose at
Shape) and the electric welded steel pipe of manufacture, it is the electric welded steel pipe for not having to implement the heat treatment other than weld seam heat treatment after roll forming.
The preferred mode of the process of manufacture as-rolled condition electric welded steel pipe in preparation method A can be described below.
Preparation method A preferably has following sizing processes between the process and tempering process of manufacture as-rolled condition electric welded steel pipe：
The shape of as-rolled condition electric welded steel pipe is adjusted to the variable quantity (hereinafter also referred to " sizing of front and back roundness by sizing mill
Roundness variable quantity (%) ") reach 1.0% or more condition and is adjusted.
Preparation method A have sizing process in the case of, it is easier to manufacture above-mentioned specific precipitate area occupation ratio be 0.10~
1.00% electric welded steel pipe.
Its reason be presently considered to be because：Reach the above-mentioned sizing of 1.0% or more condition by sizing roundness variable quantity
Process so that dislocation more than a degree of amount is introduced into the inside of as-rolled condition electric welded steel pipe, later, by rolling
State electric welded steel pipe implements the tempering of the temperature of 400 DEG C~Ac1 points so that fine specific precipitate becomes easy in dislocation
It is precipitated.
Here, the roundness of as-rolled condition electric welded steel pipe is operated and is found out as described below.
First, 4 measurement are obtained by measuring the outer diameter of as-rolled condition electric welded steel pipe for pipe circumferential direction with 45 ° of spacing
Value.Maximum value, minimum value and the average value in obtained 4 measured values are found out respectively.Based on maximum value, minimum value and it is averaged
Value, the roundness of as-rolled condition electric welded steel pipe is found out by following formula.
The roundness of as-rolled condition electric welded steel pipe=(maximum value-minimum value)/average value
In addition, sizing roundness variable quantity (%) is welded based on the as-rolled condition before the Adjusting Shape carried out using sizing mill
The roundness of steel pipe and using sizing mill carry out Adjusting Shape after as-rolled condition electric welded steel pipe roundness and by following formula
Son is found out.
Sizing roundness variable quantity (%)=(| the as-rolled condition electric welded steel pipe after the Adjusting Shape carried out using sizing mill
The Adjusting Shape that is carried out using sizing mill of roundness-before as-rolled condition electric welded steel pipe roundness |/utilize sizing mill to carry out
Adjusting Shape before as-rolled condition electric welded steel pipe roundness) × 100
The process of manufacture as-rolled condition electric welded steel pipe in preparation method A preferably has following processes：
Hot-rolled process, by being heated to the steel billet (slab) with above-mentioned chemical composition, and will be warmed-up
Steel billet carries out hot rolling, to obtain hot rolled steel plate；
Cooling process cools down the hot rolled steel plate obtained in hot-rolled process；
Rolling step, by being wound to the hot rolled steel plate being cooled in cooling process, to obtain by heat
The hot rolling material that rolled steel plate is formed；With
Tubing process carries out rolling by unreeling out hot rolled steel plate from hot rolling material, and to the hot rolled steel plate after unreeling
Forming, to which open tube be made, is resistance welded by the docking section to obtained open tube by forms resistance weld,
To obtain as-rolled condition electric welded steel pipe.
For tubing process, after resistance welding, weld seam heat treatment can also be implemented to resistance weld as needed.
In hot-rolled process, the steel billet (slab) with above-mentioned chemical composition is preferably heated to 1150 DEG C~1350 DEG C
Temperature.
If the temperature for heating steel billet is 1150 DEG C or more, the toughness in the base material portion of electric welded steel pipe can be made further to carry
It is high.Its reason be presently considered to be because：If the temperature for heating steel billet is 1150 DEG C or more, the Nb not being dissolved can be inhibited to be carbonized
The generation of object.
If the temperature of the heating of steel billet be 1350 DEG C hereinafter, if the toughness in the base material portion of electric welded steel pipe can be made further
It improves.Its reason be presently considered to be because：If the heating temperature of steel billet be 1350 DEG C hereinafter, if can inhibit the thick of metal structure
Bigization.
In hot-rolled process, preferably for example to be heated to 1150 DEG C~1350 DEG C temperature steel billet in+100 DEG C of Ar3 points
Above temperature carries out hot rolling.Thereby, it is possible to improve the quenching degree of hot rolled steel plate.
Wherein, Ar3 points are found out by the chemical composition in base material portion by following formulas.
Ar3 (DEG C)=910-310C-80Mn-55Ni-20Cu-15Cr-80Mo
(wherein, C, Mn, Ni, Cu, Cr and Mo are respectively the quality % of each element.Ni, Cu, Cr and Mo are optional element,
For not by containing the element in steel billet, Ar3 points are calculated with 0 mass % in these optional elements.〕
In cooling process, the beginning of cooling temperature is preferably set as Ar3 points or more come to being obtained in hot-rolled process
Hot rolled steel plate is cooled down.Thereby, it is possible to so that the intensity in base material portion and toughness is further increased.Its reason be presently considered to be because：
By the way that the beginning of cooling temperature is set as Ar3 points or more, the generation of coarse polygonal ferrite can inhibit.
In cooling process, preferably fast with the cooling of 5 DEG C/s~80 DEG C/s to the hot rolled steel plate obtained in hot-rolled process
Degree is cooled down.
If cooling velocity is 5 DEG C/s or more, the toughness deterioration in base material portion can be further suppressed.Its reason evidence is recognized
To be because：It is 5 DEG C/s or more by the cooling velocity in cooling process so that coarse ferritic generation is inhibited.
If cooling velocity be 80 DEG C/s hereinafter, if base material portion toughness deterioration can be inhibited.Its reason is presently considered to be
Because：By the cooling velocity in cooling process for 80 DEG C/s hereinafter, can inhibit the second phase fraction becomes excessive (i.e. ferrite point
60%) rate is got lower than.
Rolling step preferably to the hot rolled steel plate that has been cooled in cooling process with 450~650 DEG C of coiling temperature into
Row winding.
If coiling temperature is 450 DEG C or more, the toughness deterioration in base material portion can be inhibited.Its reason be presently considered to be because
For：If coiling temperature is 450 DEG C or more, the generation of martensite can be suppressed.
If coiling temperature be 650 DEG C hereinafter, if can inhibit the rising of YR.Its reason be presently considered to be because：If volume
Around temperature for 650 DEG C hereinafter, then excessive generate of Nb carbonitrides can be suppressed, as a result, the rising of YS can be inhibited.
Embodiment
Hereinafter, embodiments herein is shown, but the application is not limited to embodiment below.
(embodiment 1~17, comparative example 1~26)
<The manufacture of hot rolling material>
By that will have the temperature of the heating steel billet to 1250 DEG C of chemical composition shown in table 1 and table 2, to warmed-up
Steel billet carry out hot rolling and hot rolled steel plate is made, the beginning of cooling temperature is set as to 820 DEG C and to obtained hot rolled steel plate with 50
DEG C/cooling velocity of s carry out it is cooling, the hot rolled steel plate being cooled is wound with 550 DEG C of coiling temperature, to obtain
The hot rolling material that is formed by hot rolled steel plate.
In each embodiment and each comparative example, remainder other than element shown in table 1 and table 2 is Fe and miscellaneous
Matter.
In table 1 and 2, the REM in embodiment 11 is Ce, and the REM in embodiment 16 is Nd, and the REM in embodiment 17 is
La。
In table 1~3, the numerical value with underscore is the numerical value outside scope of the present application.
<The manufacture of as-rolled condition electric welded steel pipe>
Hot rolled steel plate is unreeled out from above-mentioned hot rolling material, is made by carrying out roll forming to the hot rolled steel plate after unreeling
Open tube is resistance welded the docking section of obtained open tube and forms resistance weld (hereinafter also referred to as " welding
Portion "), then, by carrying out weld seam heat treatment to weld part, to obtain as-rolled condition electric welded steel pipe.
<The manufacture (sizing mill and tempering) of electric welded steel pipe>
The shape of the rolling state electric welded steel pipe is changed by sizing mill with reaching sizing roundness shown in table 3
The condition of amount (%) is adjusted.
When by the way that the as-rolled condition electric welded steel pipe after Adjusting Shape being implemented based on temperature shown in table 3 and is tempered
Between tempering, to obtain electric welded steel pipe.
The outer diameter of obtained electric welded steel pipe is 219mm, and the wall thickness of the electric welded steel pipe is 15.9mm.
In addition, above manufacturing process will not impact the chemical composition of steel.Therefore, obtained electric welded steel pipe
The chemical composition in base material portion can be considered identical as the chemical composition of the steel billet as raw material.
<It measures>
Measurement below has been carried out to obtained electric welded steel pipe.
It shows the result in table 3.
(ferrite divides the confirmation of the measurement of rate and the tissue of the second phase)
Ferrite point rate (" F points of rate " in table 3) is measured by above-mentioned method, and confirmed the type of the second phase.
In table 3, TB refers to tempering bainite, and P refers to pearlite, and MA refers to island-like martensite.
(measurement of YS, TS and YR)
Become electric welded steel pipe from 90 ° of positions of base material of electric welded steel pipe along the experiment direction (draw direction) of tension test
The test film of the direction acquisition tension test of tube axial direction (hereinafter also referred to " directions L ").Here, the shape setting of test film
For the writing board shape according to american petroleum institute standard API 5L (hereinafter, being abbreviated as " API 5L ").
Using the test film of acquisition, at room temperature, according to API 5L, into the L for being about to test direction and being set as electric welded steel pipe
The tension test in direction determines the TS in the directions L of the electric welded steel pipe and YS in the directions L of electric welded steel pipe respectively.
In addition, having found out the YR (%) in the directions L of electric welded steel pipe by formula " (YS/TS) × 100 ".
(measurement of the vE (J) (0 DEG C of Charpy impact absorbs energy) in base material portion)
From full-scale test piece of the 90 DEG C of station acquisitions of base material with V-notch of electric welded steel pipe (Charpy-type test
Test film).Full-scale test piece with V-notch acquires in such a way that experiment direction becomes pipe circumferential direction (directions C).For
The full-scale test piece with V-notch of acquisition carries out Charpy-type test according to API 5L, surveys under 0 DEG C of temperature condition
VE (J) is determined.
Every 1 electric welded steel pipe carries out 5 above-mentioned measurement, using the average value of 5 measured values as the electric welded steel pipe
The vE (J) in base material portion.
(measurement of the vE (J) (0 DEG C of Charpy impact absorbs energy) of weld part)
Other than the position for acquiring the full-scale test piece with V-notch is changed to the weld part of electric welded steel pipe, into
It has gone and has similarly been operated with the measurement of the vE in base material portion (J).
(measurement of specific precipitate area occupation ratio)
By above-mentioned method, determining specific precipitate area occupation ratio, (i.e. equivalent circle diameter is 100nm precipitates below
Area occupation ratio；It is abbreviated as in table 3 " precipitate area occupation ratio (%) ").
[table 1]
[table 2]
[table 3]
As shown in 1~table of table 3, the electric welded steel pipe of each embodiment meets TS, YS, YR, vE (mother in the application
Material portion) and vE (weld part).That is, showing that the electric welded steel pipe of each embodiment has a degree of tensile strength and surrender strong
Degree, yield ratio are minimized, the excellent tenacity of base material portion and weld part.
For C amounts have been more than the comparative example 1 of the upper limit, F points of rate reduces, and YR is got higher.
For Si amounts have been more than the comparative example 2 of the upper limit, the toughness of weld part deteriorates.
For comparative example 3 of the Si amounts less than lower limit, the toughness of base material portion and weld part deteriorates.Its reason be presently considered to be because
For：Deoxidation becomes inadequate, and produces coarse oxide.
For comparative example 4 of the Mn amounts less than lower limit, the toughness of base material portion and weld part deteriorates.Its reason be presently considered to be because
For：It produces brittle because of caused by S.
For Mn amounts have been more than the comparative example 5 of the upper limit, the toughness of base material portion and weld part deteriorates.Its reason is presently considered to be
Because：It becomes easy and generates the crackle caused by MnS.
For comparative examples 6 of the Ti less than lower limit, the toughness of base material portion and weld part deteriorates.Its reason be presently considered to be because
For：Crystal grain becomes thick.
For Ti has been more than the comparative example 7 of the upper limit, the toughness of base material portion and weld part deteriorates.Its reason be presently considered to be because
For：Generate coarse TiN.
For comparative examples 8 of the Nb less than lower limit, the toughness in base material portion deteriorates.Its reason be presently considered to be because：It does not tie again
Crystalline substance rolling becomes inadequate.
For Nb has been more than the comparative example 9 of the upper limit, the toughness of base material portion and weld part deteriorates.Its reason be presently considered to be because
For：Generate coarse Nb carbonitrides.
For comparative examples 10 of the Al less than lower limit, the toughness of base material portion and weld part deteriorates.Its reason be presently considered to be because
For：Deoxidation becomes inadequate.
For Al has been more than the comparative example 11 of the upper limit, the toughness of weld part deteriorates.Its reason be presently considered to be because：Largely
Ground generates Al systems field trash.
For CMeq has been more than the comparative example 12 of the upper limit, YS and TS have been more than the upper limit.
For comparative examples 13 of the CMeq less than lower limit, F divides rate to be more than the upper limit, and TS is less than lower limit.
For comparative examples 14 of the LR less than 0.210, yield ratio has been more than 90%.
For comparative example 15, YS and YR have been more than the upper limit.Its reason be presently considered to be because：Since temperature is too low,
Therefore make the effect (making the effect that dislocation density reduces by tempering) for mitigating tubing strain insufficient by tempering,
And it is precipitated in dislocation insufficient.
For comparative example 16, (i.e. the vE of base material portion and weld part is below down for the toughness reduction of base material portion and weld part
Limit).Its reason be presently considered to be because：Since temperature is excessively high, the phase transformation to austenite is caused in a part of region,
The concentration of C is got higher in above-mentioned a part of region, as a result, the cooling after passing through, causes to generate island-like martensite
(MA)。
For comparative example 17, YR has been more than 90%.Its reason be presently considered to be because：Due to sizing roundness variable quantity
It is small, thus dislocation importing and dislocation on be precipitated it is insufficient.
For comparative example 18, YR has been more than 90%.Its reason be presently considered to be because：Since tempering time is short, position
It is precipitated in mistake insufficient.
For comparative example 19 of the N amounts less than lower limit, the toughness of base material portion and weld part deteriorates.Its reason be presently considered to be because
For：Crystal grain becomes thick.
For N amounts have been more than the comparative example 20 of the upper limit, the toughness of base material portion and weld part deteriorates.Its reason is presently considered to be
Because：Carbide becomes thick.
For comparative example 21~23, YR has been more than 90%.Its reason be presently considered to be because：Since sizing roundness changes
Measure it is small, therefore dislocation importing and dislocation on be precipitated it is insufficient.
For Mn/Si ratios are 2.0 comparative examples 24 below, the toughness of weld part deteriorates.
For comparative examples 25 and 26 of the LR less than 0.210, yield ratio has been more than 90%.
Japanese patent application 2016-056858 disclose its entirely through with reference to and be included in this specification.
Whole documents, patent application and technical standard described in this specification with it is specific and respectively describe " each
Document, patent application and technical standard by referring to and be included in " the case where to same extent by referring to and be included in this specification
In.
Claims (5)
1. a kind of spool electric welded steel pipe, it includes base material portion and resistance weld,
The chemical composition in the base material portion includes in terms of quality %：
C：0.080~0.120%,
Mn：0.30~1.00%,
Ti：0.005~0.050%,
Nb：0.010~0.100%,
N：0.001~0.020%,
Si：0.010~0.450%,
Al：0.001~0.100%,
P：0~0.030%,
S：0~0.0100%,
Mo：0~0.50%,
Cu：0~1.00%,
Ni：0~1.00%,
Cr：0~1.00%,
V：0~0.100%,
Ca：0~0.0100%,
Mg：0~0.0100%,
REM：0~0.0100% and
Remainder：Fe and impurity,
Wherein, the CMeq shown in following formula (1) is 0.170~0.300,
The ratio between the quality % of the quality % of Mn relative to Si are 2.0 or more,
The LR shown in following formula (2) is 0.210 or more,
In the case where observing the metal structure in the base material portion using scanning electron microscope with 1000 times of multiplying power, by iron
The area occupation ratio for the first phase that ferritic is formed is 60~98%, and the second phase as remainder includes tempering bainite,
The yield strength of tube axial direction is 390~562MPa,
The tensile strength of tube axial direction is 520~690MPa,
The yield ratio of tube axial direction be 90% hereinafter,
The Charpy impact absorption of the pipe circumferential direction in the base material portion can be 100J or more at 0 DEG C,
The Charpy impact absorption of the pipe circumferential direction of the resistance weld can be 80J or more at 0 DEG C,
CMeq=C+Mn/6+Cr/5+ (Ni+Cu)/15+Nb+Mo/3+V formulas (1)
LR=(2.1 × C+Nb)/Mn formulas (2)
In formula (1) and formula (2), C, Mn, Cr, Ni, Cu, Nb, Mo and V indicate the quality % of each element respectively.
2. spool electric welded steel pipe according to claim 1, wherein the chemical composition in the base material portion is contained in terms of quality %
Have：
Mo：More than 0% and for 0.50% or less,
Cu：More than 0% and for 1.00% or less,
Ni：More than 0% and for 1.00% or less,
Cr：More than 0% and for 1.00% or less,
V：More than 0% and for 0.100% or less,
Ca：More than 0% and for 0.0100% or less,
Mg：More than 0% and for 0.0100% or less and
REM：More than 0% and it is 0.0100% or less
In it is one kind or two or more.
3. the spool electric welded steel pipe according to claim 1 or claim 2, wherein micro- using transmission electron
In the case that mirror observes the metal structure in the base material portion with 100000 times of multiplying power, equivalent circle diameter is 100nm analysis below
The area occupation ratio for going out object is 0.10~1.00%.
4. according to the spool electric welded steel pipe described in 1~claim 3 of claim wantonly 1, wherein the change in the base material portion
The content for learning the Nb in composition is calculated as 0.020% or more with quality %.
5. according to the spool electric welded steel pipe described in 1~claim 4 of claim wantonly 1, wall thickness is 10~25mm, outside
Diameter is 114.3~609.6mm.
Applications Claiming Priority (3)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP2016-056858 | 2016-03-22 | ||
| JP2016056858 | 2016-03-22 | ||
| PCT/JP2017/010023 WO2017163987A1 (en) | 2016-03-22 | 2017-03-13 | Electric resistance welded steel tube for line pipe |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CN108368582A true CN108368582A (en) | 2018-08-03 |
Family
ID=59899525
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CN201780004490.4A Pending CN108368582A (en) | 2016-03-22 | 2017-03-13 | Spool electric welded steel pipe |
Country Status (5)
| Country | Link |
|---|---|
| EP (1) | EP3375900A4 (en) |
| JP (1) | JP6213703B1 (en) |
| KR (1) | KR20180077259A (en) |
| CN (1) | CN108368582A (en) |
| WO (1) | WO2017163987A1 (en) |
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| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JP6841392B2 (en) * | 2019-02-21 | 2021-03-10 | 日本製鉄株式会社 | How to use high-strength electric resistance pipes and high-strength electric resistance pipes for ground stabilization work |
| JP6690787B1 (en) * | 2019-03-29 | 2020-04-28 | Ｊｆｅスチール株式会社 | ERW steel pipe, its manufacturing method, and steel pipe pile |
| WO2021038632A1 (en) | 2019-08-23 | 2021-03-04 | 日本製鉄株式会社 | Electric-resistance-welded steel pipe for line pipes |
| TR201921217A2 (en) * | 2019-12-24 | 2021-07-26 | Tirsan Kardan Sanayi Ve Ticaret Anonim Sirketi | High strength, low alloy steel composition |
| EP4066954A4 (en) * | 2020-02-10 | 2023-07-05 | Nippon Steel Corporation | Line pipe-use electric resistance welded steel pipe |
| WO2021200402A1 (en) | 2020-04-02 | 2021-10-07 | Ｊｆｅスチール株式会社 | Electroseamed steel pipe, and method for manufacturing same |
| JP6885524B1 (en) | 2020-08-28 | 2021-06-16 | 日本製鉄株式会社 | Electric resistance steel pipe |
| EP4206345A4 (en) * | 2020-10-05 | 2024-01-17 | Jfe Steel Corp | Electric resistance welded steel pipe and method for manufacturing same |
| WO2023014330A1 (en) * | 2021-08-04 | 2023-02-09 | Ti̇rsan Kardan Sanayi̇ Ve Ti̇caret Anoni̇m Şi̇rketi̇ | New micro-alloy steel |
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- 2017-03-13 KR KR1020187015522A patent/KR20180077259A/en active IP Right Grant
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Also Published As
| Publication number | Publication date |
|---|---|
| JPWO2017163987A1 (en) | 2018-03-29 |
| WO2017163987A1 (en) | 2017-09-28 |
| KR20180077259A (en) | 2018-07-06 |
| JP6213703B1 (en) | 2017-10-18 |
| EP3375900A1 (en) | 2018-09-19 |
| EP3375900A4 (en) | 2019-07-17 |
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