Longitudinal resistance welded pipe is with the method for manufacture of X80 pipe line steel and hot-rolled sheet coil thereof
Technical field
The invention belongs to the high-strength low-alloy steel technical field; Relate generally to the method for manufacture of a kind of pipe-line with pipe line steel and hot-rolled sheet coil thereof, especially in the API SPEC 5L standard a kind of longitudinal resistance welded pipe with the method for manufacture of X80 grade of steel pipe line steel and hot-rolled sheet coil thereof.
Background technology
Pipeline transportation is most economical, safe, the efficient and environmental transportation method of material such as long distances oil and gas; For reducing pipe-line construction and operation cost; Improve transport efficiency, adopt high pressure, heavy caliber transport gas to become long main flow trend, impel pipe line steel to develop to HS, H.T. direction apart from NG Pipeline Construction; The X70-X80 pipe line steel has become the main flow grade of steel of international long-distance transport pipes engineering, and market outlook are extensive.
The oil of present world overwhelming majority of countries, the natural-gas transfer pipeline engineering is all followed the API SPEC of API 5L standard or the ISO of International Standards Organization 3183 with the pipe line steel steel pipe standard; Pipework is divided into spiral submerged arc welded steel pipe, vertical masonry joint electricresistance welded steel pipe and longitudinal submerged arc welded pipe with steel pipe by the tubulation mode, and corresponding three kinds of raw materials that welded tube adopted are respectively hot-rolled sheet coil and hot-rolled steel sheet.
The key problem in technology of thick specification X80 line steel hot rolling roll bending development is to guarantee the HS of product and good low temperature fracture toughness, and low cost prodn.For taking into account requirements such as HS, good low-temperature toughness and good welds performance simultaneously, the X80 pipe line steel generally all adopts acicular ferrite structure's design.Before the present invention, existing a plurality of document and patents of invention about the X80 pipe line steel, but the vertical masonry joint resistance welding is with X80 pipe line steel report seldom, document that following brief account and the present invention are comparatively approaching and patent:
1) Deng Wei etc., the tissue and the performance of high niobium X80 pipe line steel, Northeastern University's journal, 2009, No.9.This paper is laboratory study, and finished product thickness is 12mm, not industrial applications.
2)Navid?Pourkia,PiroozMarash.The?Effect?of?Weld?Metal?ManganeseContent?on?the?Microstructure,JFE?Technical?Report,2008,No.8。This paper relates to manufacturing X80 high-frequency resistance welded tube, but contains Mo in the composition, thickness of strand 215mm, finished product thickness 16mm.
3) Chinese patent CN101413090A, a kind of high-strength high-toughness X 80 hot rolling coiled sheet for spiral buried arc welding and method of manufacture thereof.Contain Mo:0.10-0.30% in the composition, and the thick 230mm of continuously cast bloom, finished product thickness 12-19mm is used for spiral welded tube.
4) Chinese patent CN 101270441A, a kind of economy type X 80 pipeline steel and working method thereof.Strand and finished product thickness are indicated in the alternative Mo≤0.50wt% that adds of this patent, the slab finishing of need rolling off the production line, and are used for ERW.
5) Chinese patent CN 1715434A, high-intensity high-tenacity X80 pipe line steel and hot-rolled coil method of manufacture thereof.The thick 250mm of continuously cast bloom, composition contains Mo:0.20-0.40%, and finished product thickness is used for spiral welded tube less than 15mm.
6) Chinese patent CN 1715434A has anti-HIC performance X80 pipe line steel and hot rolled plate making process thereof.The thick 250mm of continuously cast bloom contains Mo:0.20-0.40% in the composition, finished product thickness is used for spiral welded tube less than 15mm.
7) Chinese patent CN 1584097A, high-intensity high-tenacity line of pipes steel and preparation method thereof.The thick 230mm of continuously cast bloom contains Mo:0.10-0.40% in the composition, thickness 15mm and 17.5mm are used for spiral welded tube.
8) Japanese Patent JP 10102184, make high-strength electric resistance welded steel pipe and use hot-rolled steel sheet.Be used for the vertical masonry joint resistance welding, ingredient w t%:C, 0.04-0.08%; Si, 0.10-0.30%; Mn, 1.20-1.70%; Ti, 0.020-0.070%; Nb, 0.030-0.080%; Mo, 0.10-0.50% can add Cu, 0.20-0.50%; Ni, 0.10-0.40%; V, 0.030-0.010, thickness 5.3-12.7mm.
Wherein 3), 5), 6), 7) patent is and makes the patent of invention of spiral submerged arc welded steel pipe with the X80 hot-rolled coil, and is different with product of the present invention.And document 2) and patent 4), 8) the most approaching with product of the present invention, be and make the patent of invention of vertical masonry joint electricresistance welded steel pipe with the X80 hot-rolled sheet coil, all obvious difference is arranged with the present invention.
The disclosed X80 pipe line steel of above document and patent has reached HS and H.T. etc., but contains noble metal Mo in the alloy, and cost is higher; And adopt 215,230 or the thick continuous casting steel billet of 250mm, the slab finishing of how need rolling off the production line before the continuously cast bloom reheat, heat-energy losses is bigger; Production cycle is longer; Problems such as production cost height, the while patent documentation is the coiled sheet thinner thickness openly, is difficult to satisfy the needs of high pressure, heavy wall long distance pipeline engineering steel.
Summary of the invention
The objective of the invention is to overcome the deficiency that above-mentioned prior art exists, a kind of method of manufacture with longitudinal resistance welded pipe of good low-temperature flexibility with thick specification API X80 grade of steel line steel hot rolling roll bending and low cost prodn thereof is provided.
The present invention is achieved in that this longitudinal resistance welded pipe uses the chemical component weight per-cent of X80 pipe line steel to be: C 0.025%-0.065%, Si 0.10%-0.35%, Mn 1.68%-1.85%, Nb0.06%-0.11%, Cr 0.20%-0.35%, Ti 0.005%-0.020%, Als 0.015%-0.045%, P≤0.020%, S≤0.005%, Ca 0.001%-0.004%, N≤0.006%; Also contain among Ni0.10%-0.25%, Cu 0.10%-0.25%, the V 0.01%-0.04% one or more; Surplus is iron and unavoidable impurities, and cold crack sensitivity coefficient Pcm≤0.19%.
The composition design philosophy of the thick specification X80 pipe line steel of the present invention is with low C, high Mn, high Nb; Through adding microalloy element such as trace Ti, and Cr, Cu, Ni alloying element; Linkage heat machinery controlled rolling production technique obtains tiny acicular ferrite structure; Guaranteeing that pipe line steel has the performance of high-intensity high-tenacity, its main fundamental element and effect as follows:
C: be strengthening element most economical, the most basic in the steel, the intensity that improves steel had obvious effect, ductility, toughness and the weldableness of steel had negative impact but improve C content through solution strengthening and precipitation strength.Carbon content of the present invention is 0.025-0.065%, and low-carbon (LC) guarantees that pipe line steel has good low-temperature toughness, good welds performance and anti-hydrogen induced cracking (HIC) performance.
Mn:, be that compensation reduces the main and most economical strengthening element that causes loss of strength in the pipe line steel because of C content through the intensity of solution strengthening raising steel.Mn still enlarges the element of γ phase region, can reduce the γ-α transformation temperature of steel, helps to obtain tiny phase-change product, can improve toughness, the reduction ductile-brittle transition temperature of steel.Manganese content of the present invention is 1.68-1.85%, and high manganese promotes acicular ferrite nucleating, and high Mn/C can improve steel ys and impelling strength, reduces ductile-brittle transition temperature.
Nb: be one of topmost element in the modern microalloying pipe line steel, fairly obvious to the effect of grain refining.Separate out the austenitic answer of obstruction deformation, recrystallize through NbC strain inducing in the course of hot rolling; The deformation austenite structure that makes non-recrystallization zone of finish rolling stage through controlled rolling and controlled chilling changes tiny phase-change product into during in phase transformation, so that steel has more HS and H.T..
Cr: can effectively improve hardening capacity, suppress polygonal ferrite and pearlitic generation, promote in middle gentle cold zone, to form ferritic or the bainite that intracrystalline has a large amount of dislocations to distribute, use more remarkable effect with the Nb combination.
Ti: be strong solid N element, the stoichiometric ratio of Ti/N is 3.42, utilizes the Ti fixing N below the 60ppm in the steel just about 0.02%, when sheet billet continuous casting, can form the TiN precipitated phase of tiny high-temperature stable.Austenite crystal when this tiny TiN particle can hinder the slab reheat is effectively grown up, and helps to improve the solid solubility of Nb in austenite, simultaneously the impelling strength of improving welded heat affecting zone is had obvious effect.
Cu, Ni: can improve the intensity of steel through the solution strengthening effect, Cu can also improve the solidity to corrosion of steel simultaneously, and the adding of Ni mainly is to improve Cu in steel, to be prone to the red brittleness that causes, and useful to toughness.In thick specification pipe line steel, can compensate the strength degradation that the increase because of thickness causes.
V: have higher precipitation strength effect and more weak grain refining effect, V mainly is through in ferritic, improve the intensity of steel with the VC precipitation strength.
Pcm: control cold crack sensitivity coefficient helps ensureing the welding property of product, and Pcm of the present invention is controlled at 0.14%~0.19%.
Longitudinal resistance welded pipe of the present invention is to adopt intermediate gauge slab continuous casting rolling production technique with the method for manufacture of X80 pipe line steel; Its technical process is: hot metal pretreatment-converter smelting-external refining-continuous casting-rolling is characterized in: converter smelting adopts top blast or top bottom blowing; External refining adopts RH vacuum-treat, the frivolous sulphuring treatment of LF stove and calcium to handle ductility, toughness and cold-bending property with control inclusion morphology and raising steel; Continuous casting adopts and dynamically gently to depress, to control the center segregation quality of continuous casting steel billet; The thick continuously cast bloom of application 1 35mm or 170mm; Obviously be thinner than the main at present thick continuously cast bloom of using in the 250mm left and right sides, it solidifies rate of cooling and is far longer than traditional heavy slab, and secondary dendrite arm spacing reduces significantly; Continuous casting adopts two cold curves dynamically to control, and guarantees the surface quality of high-niobium pipeline steel continuous casting billet; Continuously cast bloom directly carries out the heating of hot charging stove 500-850 ℃ of temperature; After walking beam furnace was heated to 1130-1230 ℃, through roughing and finishing train two stages controlled rolling, the breaking down temperature was 1100-980 ℃; Final rolling temperature is 960-750 ℃; Finishing temperature is 750-830 ℃, and coiled sheet cools off with the speed of 10-20 ℃/s through the laminar flow cooling fast, and coiling temperature is 480-560 ℃.
The present invention produces above-mentioned thick specification X80 hot-rolled sheet coil and adopts vertical masonry joint resistance welding (being called for short ERW or HFW) to process steel pipe; By the API 5L of API standard code; The ys of above-mentioned X80 grade of steel steel pipe body is 555-705MPa, tensile strength 625-825MPa, elongation >=16%; Room temperature Charpy-V impact power (3 samples) Akv >=54J, the average DWTT of room temperature (being called for short DWTT) shear area (2 samples) SA >=85%.
It is acicular ferrite structure's design that X80 line steel hot rolling coiled sheet of the present invention adopts C-Mn-Cr-Nb;, can select to add alloying elements such as V, Ni and Cu for Mo with Cr, not add the B alloying element; Cost of alloy is low, and product reaches the requirement of API SPEC 5L code requirement X80 pipe line steel; Adopt 135mm or the thick continuously cast bloom of 170mm, produce thick specification X80 line steel hot rolling roll bending at short flow process continuous casting continuous casting line, the thickest specification can reach 19.5mm; Adopt and dynamically gently to depress continuous casting technology, and continuous casting steel billet can directly carry out hot charging stove reheat 500-850 ℃ of temperature, improve the heat energy service efficiency and saved the energy, shorten the production cycle, enhance productivity, reduce production costs greatly; X80 pipe line steel of the present invention has good comprehensive toughness and tenacity and good welding property: its intensity satisfies API SPEC 5L code requirement;-20 ℃ of Charpy-V impact powers reach more than the 300J; Shear area is greater than 85%, and the shear area of-15 ℃ of DWTTs is greater than 85%; Its cold crack sensitivity coefficient Pcm is not more than 0.19%, uses rational welding material and weldprocedure, can obtain good welding property.
Embodiment
Through embodiment the present invention is done further description below.
Enumerate embodiments of the invention below only to the description of best mode for carrying out the invention, but scope of the present invention is not had any restriction.Table 1 is the chemical ingredients of embodiment of the invention steel.Its technical process is hot metal pretreatment-converter smelting-external refining (processing of RH+LF+ calcium)-continuous casting-rolling, and the concrete process system of embodiment steel is seen table 2.Table 3 is the mechanical property of embodiment of the invention steel.
Visible by table 3, the longitudinal resistance welded pipe that adopts technical scheme production of the present invention has good comprehensive mechanical properties and welding property with X80 line steel hot rolling coiled sheet, can be used to make the X80 grade of steel steel pipe that satisfies API SPEC 5L standard-required.
The chemical ingredients of table 1 embodiment of the invention steel (wt, %)
Classification |
C |
Si |
Mn |
P |
S |
Als |
Cr |
Cu |
Ni |
Nb |
V |
Ti |
N |
Ca |
Pcm |
Embodiment 1 |
0.045 |
0.20 |
1.83 |
0.012 |
0.0022 |
0.032 |
0.28 |
0.22 |
0.19 |
0.09 |
- |
0.013 |
0.0042 |
0.0018 |
0.17 |
Embodiment 2 |
0.062 |
0.25 |
1.68 |
0.010 |
0.0015 |
0.020 |
0.23 |
0.18 |
0.18 |
0.07 |
- |
0.008 |
0.0036 |
0.0022 |
0.17 |
Embodiment 3 |
0.041 |
0.26 |
1.82 |
0.013 |
0.0011 |
0.027 |
0.25 |
0.16 |
0.15 |
0.10 |
0.03 |
0.009 |
0.0048 |
0.0015 |
0.16 |
Embodiment 4 |
0.035 |
0.24 |
1.79 |
0.014 |
0.0026 |
0.028 |
0.29 |
0.18 |
0.16 |
0.09 |
- |
0.011 |
0.0031 |
0.0022 |
0.15 |
Embodiment 5 |
0.027 |
0.22 |
1.82 |
0.008 |
0.0018 |
0.025 |
0.27 |
0.18 |
0.17 |
0.11 |
- |
0.010 |
0.0030 |
0.0028 |
0.14 |
Embodiment 6 |
0.051 |
0.32 |
1.75 |
0.009 |
0.0015 |
0.033 |
0.26 |
0.17 |
0.17 |
0.09 |
0.03 |
0.012 |
0.0050 |
0.0020 |
0.17 |
Embodiment 7 |
0.043 |
0.27 |
1.77 |
0.011 |
0.0021 |
0.030 |
0.029 |
- |
- |
0.10 |
0.025 |
0.015 |
0.0044 |
0.0025 |
0.145 |
Embodiment 8 |
0.056 |
0.19 |
1.72 |
0.013 |
0.0019 |
0.026 |
0.027 |
- |
- |
0.11 |
0.035 |
0.017 |
0.0037 |
0.0019 |
0.16 |
Annotate: Pcm=C+Si/30+ (Mn+Cu+Cr)/20+Ni/60+Mo/15+V/10+5B.
The process system of table 2 embodiment of the invention steel
The mechanical property of table 3 embodiment of the invention steel