CN102828121B

CN102828121B - K55-grade high frequency resistance welding oil casting steel and its manufacturing method

Info

Publication number: CN102828121B
Application number: CN201110160119.1A
Authority: CN
Inventors: 黄明浩; 黄国建; 张禄林; 张英慧; 孔祥磊; 徐烽
Original assignee: Angang Steel Co Ltd
Current assignee: Angang Steel Co Ltd
Priority date: 2011-06-14
Filing date: 2011-06-14
Publication date: 2014-12-31
Anticipated expiration: 2031-06-14
Also published as: CN102828121A

Abstract

The invention provides K55-grade high frequency resistance welding oil casting steel and its manufacturing method. The steel provided by the invention comprises the following chemical components of: by weight, 0.055-0.095% of C, 0.15-0.30% of Si, 1.50-1.85% of Mn, P being less than or equal to 0.020%, S being less than or equal to 0.008%, 0.010-0.050% of Ti, 0.02-0.06% of Als, 0.04-0.07% of Nb, 0.23-0.31% of Cr, 0.01-0.04% of V, N being less than or equal to 0.008%, and the balance Fe. The method provided by the invention comprises smelting, continuous casting and rolling technologies. A continuous casting slab is heated to 1200-1300 DEG C and undergoes two-stage controlled rolling. During the first stage, rolling temperature is 1100-1200 DEG C, and finishing temperature is greater than 980 DEG C; and during the second stage, rolling temperature is less than 960 DEG C and finishing temperature is 820-880 DEG C. After rolling, the continuous casting slab is cooled to 770-810 DEG C at the cooling rate of 3-6 DEG C/s and is then rapidly cooled at the cooling rate of 10-15 DEG C/s. The reeling temperature is 570-630 DEG C. The K55-grade high frequency resistance welding oil casting steel provided by the invention has advantages of low C content, excellent weldability, good impact toughness, low alloy cost and simple production technology.

Description

A kind of K55 level high-frequency electric resistance welded petroleum casing pipe steel and manufacture method thereof

Technical field

The present invention relates to a kind of HFW (High frequency electric-resistance-weld, high frequency resistance welding) casing steel technology, there is in particular to one in API SPEC 5CT low yield strength ratio K55 steel level oil bushing steel and the manufacture method thereof of superior weldability and impelling strength (-10 DEG C, horizontal > 100J).

Background technology

Petroleum casing pipe is one of the most frequently used oil country tubular good in oil field, and consumption is large, and spending many, is requisite construction material in oil-gas field drill operation.HFW sleeve pipe is compared with seamless tube, and significant advantages such as having uniform wall thickness, dimensional precision is high, perforation property good, Anti-collapse ability is strong, cost is low, substitutes traditional weldless steel tube gradually.

API Spec 5CT specifies: the yield strength of K55 rank steel pipe is between 379-552MPa, tensile strength >=655MPa, elongation >=20%, ballistic work does not have mandatory requirement, Akv (21 DEG C can be selected, laterally) >=20J, the raising required oilfield safety along with people, proposes certain requirement to the impact property of raw material steel band.

At present, the production technique of K55 level HFW sleeve pipe is: Composition Design adopts high-carbon design (> 0.15%), and some interpolation Alloy Elements Mo, smelt and be rolled into hot rolled strip; Then, steel band is made welded tube by HFW mode, and butt welded seam or steel pipe integral are heat-treated, carry out suitable screw thread process subsequently to pipe end, final production goes out qualified K55 rank petroleum casing pipe.Due to carbon content higher (> 0.15%), the hot rolled strip of excellent weldability cannot be obtained, not only improve the complex process degree of HFW tubulation, and reduce the production efficiency of tubulation; Higher carbon content also causes the impelling strength of steel band general simultaneously.

The Chinese patent (CN101082099A) of " a kind of low-yield-ratio straight welding oil annular tube steel and manufacture method thereof " by name and the Chinese patent (CN 101818308A) of " a kind of steel for longitudinal resistance welded pipe with low yield ratio and manufacture method thereof " by name in prior art, in its composition, C content is higher, be respectively 0.2%-0.3% and 0.15%-0.22%, to weldability and toughness unfavorable.

Be called the Chinese patent (CN101270438A) of " low yield strength ratio electric resistance welding petroleum overlaps effective normalized steel, resistance welding sleeve pipe and method for making thereof ", the Chinese patent (CN101328559A) of " low yield strength ratio oil casing pipe steel, petroleum casing pipe and method for making thereof " by name and the paper of " research and development of high frequency resistance welding K55 steel-grade bushing " by name, not only its C content is high, be respectively 0.19%-0.29%, 0.19%-0.27% and 0.20%-0.22%, to weldability and toughness unfavorable, and after tubulation, need homogeneous tube to heat-treat, complex process, production cost is high.

The Chinese patent (CN 101845583A) of " oil casing pipe steel and manufacture method thereof " by name, C content high (0.31%-0.35%) in its composition, generally, also containing Mo, cost of alloy is higher for weldability and toughness.

From above disclosed document, prior art C content is all higher, and generally, weldprocedure is complicated, and tubulation production efficiency is low for the weldability of steel band and impelling strength; What have needs interpolation expensive alloying elements Mo, and cost of alloy is higher; Needing of having carries out homogeneous tube thermal treatment, and thermal treatment process is complicated, and steel pipe's production cost is high.

Summary of the invention

The object of the invention is to overcome the deficiency existing for above-mentioned prior art, there is provided a kind of and adopt low-carbon (LC) design, there is low yield strength ratio K55 level HFW oil casing steel and the manufacture method thereof of superior weldability and impelling strength (-10 DEG C, horizontal > 100J).

The chemical component weight per-cent of K55 level high-frequency electric resistance welded petroleum casing pipe steel of the present invention is: C:0.055%-0.095%, Si:0.15%-0.30%, Mn:1.50%-1.85%, P :≤0.020%, S :≤0.008%, Ti:0.010%-0.050%, Als:0.02%-0.06%, Nb:0.04%-0.07%, Cr:0.23%-0.31%, V:0.01%-0.04%, N :≤0.008%, all the other are Fe and inevitable impurity.

C: carbon is carbide forming element, the intensity of steel is improved by solution strengthening and precipitation strength effect, the most effective element of proof strength, but too high welding property and the impelling strength of product of affecting of carbon content, it is comparatively suitable that carbon controls at 0.055%-0.095%.

Si: silicon can play solution strengthening effect, but its too high levels can make the plasticity of steel and toughness reduce, and suitable scope is 0.15%-0.30%.

Mn: manganese has solution strengthening effect, can also increase stabilization of austenite, also favourable to raising hardening capacity, effectively ensures the intensity of steel.But Fe content is excessive, can increase the center segregation tendency of continuously cast bloom, affect the homogeneity of structure of hot-strip, bring negative impact to weldquality, suitable scope is 1.50%-1.85%.

P: phosphorus is harmful element in steel, increases the cold shortness of steel, welding property is degenerated, and reduces plasticity, cold-bending property is degenerated, should control its content≤0.020%.

S: sulphur is harmful element in steel, makes steel produce red brittleness, and reduce ductility and the toughness of steel, welding property is also unfavorable, should control its content≤0.008%.

Nb: niobium is thin brilliant and precipitation strength element, and can make up the decline of the intensity caused because carbon reduces, improving welding property, but the too high cost of alloy that can increase, suitable scope is 0.04%-0.07%.

V: the carbonitride of vanadium is evenly separated out with small and dispersed form in ferrite, can significantly improve the tensile strength of material and not obvious increase yield strength, but the too high cost of alloy that can increase, suitable scope is 0.01%-0.04%.

Ti: titanium is strong carbonitride-forming elements, remarkable fining austenite grains, can make up the decline of the intensity caused because carbon reduces.Content is too high, easily forms thick TiN, and reduce material property, suitable scope is 0.010%-0.050%.

Cr: chromium is gained in strength by solution strengthening and refined crystalline strengthening, and suitable scope is 0.23%-0.31%.

Als: aluminium is conventional reductor, adds a small amount of aluminium in steel, can crystal grain thinning, and improve impelling strength, suitable scope is 0.02%-0.06%.

N: solid solution nitrogen has the strong effect of pinning dislocation, has detrimentally affect to toughness, controls its content≤0.008%

The manufacture method of K55 level high-frequency electric resistance welded petroleum casing pipe steel of the present invention comprises smelting, continuous casting and rolling technology, and concrete technology is:

1) continuous casting process is smelted: hot metal pretreatment, converter smelting-through top blast or top bottom blowing, external refining-through RH vacuum-treat, the frivolous sulphuring treatment of LF stove and carry out Calcium treatment to control inclusion morphology and to improve the ductility of steel, toughness and cold-bending property, sheet billet continuous casting is made continuous casting steel billet-continuous casting and is adopted induction stirring or dynamic soft-reduction, to improve the quality of continuous casting steel billet.

2) rolling technology: continuous casting steel billet is heated to 1200-1300 DEG C through process furnace, carries out two-stage control rolling at 2150ASP short route hot tandem subsequently, and first stage start rolling temperature is 1100-1200 DEG C, and finishing temperature is greater than 980 DEG C; Subordinate phase start rolling temperature is less than 960 DEG C, and finishing temperature is 820-880 DEG C; Steel band after rolling cools with the two benches type of cooling of rapid cooling after first slow cooling, and slow cooling section is cooled to 770-810 DEG C with speed of cooling 3-6 DEG C/s; Rapid cooling section speed of cooling is 10-15 DEG C/s, carries out steel strip coiling 570-630 DEG C of temperature.Roll the first slow cooling of rear steel band, ensure that steel band has the soft phase constitution of a certain amount of proeutectoid ferrite, crystal grain has and to a certain degree grows up simultaneously, reduces yield strength; And then adopt cooling fast, obtain tiny bainite and the hard phase constitution of M/A, there is high tensile strength, thus ensure that steel band has low yield tensile ratio.

Compared with prior art, beneficial effect of the present invention: 1) C content lower (< 0.10%), excellent weldability, impelling strength good (-10 DEG C, horizontal > 100J); 2) replace noble element Mo with a small amount of Cr, V, save cost of alloy; 3) only need butt welded seam and heat affected zone to heat-treat after steel band tubulation, do not need homogeneous tube thermal treatment, thermal treatment process is simple, and steel pipe's production cost is low.

Embodiment

The present invention is further described by the following embodiment.

The chemical composition of embodiment of the present invention steel is in table 1, and heating, rolling, process for cooling are in table 2, and mechanical property is in table 3.

The chemical composition (wt, %) of table 1 embodiment of the present invention steel

Embodiment	C	Si	Mn	P	S	Nb	V	Ti	Cr	Als	N
												1	0.055	0.30	1.83	0.014	0.003	0.065	0.04	0.05	0.31	0.05	0.005
2	0.094	0.28	1.67	0.011	0.004	0.070	0.03	0.03	0.26	0.02	0.004
												3	0.073	0.30	1.51	0.015	0.008	0.072	0.03	0.03	0.26	0.04	0.005
4	0.078	0.22	1.61	0.010	0.007	0.067	0.01	0.02	0.29	0.02	0.003
												5	0.073	0.30	1.51	0.015	0.004	0.070	0.04	0.03	0.26	0.04	0.002
6	0.090	0.28	1.65	0.013	0.005	0.068	0.02	0.02	0.29	0.02	0.004

The heating of table 2 embodiment of the present invention steel, rolling and process for cooling

The mechanical property of table 3 embodiment of the present invention steel

From table 3, the low yield strength ratio HFW oil casing pipe steel adopting Composition Design of the present invention and rolling technology to produce, can meet API SPEC 5CT standard to the requirement of K55 level steel pipe.

Claims

1. the manufacture method of a K55 level high-frequency electric resistance welded petroleum casing pipe steel, comprise smelting, continuous casting and rolling technology, it is characterized in that described rolling technology is: continuous casting steel billet is heated to 1200-1300 DEG C through process furnace, two-stage control rolling is carried out subsequently at short route hot tandem, first stage start rolling temperature is 1100-1200 DEG C, and finishing temperature is greater than 980 DEG C; Subordinate phase start rolling temperature is less than 960 DEG C, and finishing temperature is 820-880 DEG C; Roll rear steel band to cool with two stage method, slow cooling section is cooled to 770-810 DEG C with 4-6 DEG C/s speed of cooling, and rapid cooling section speed of cooling is 10-14 DEG C/s, and coiling temperature is 570-630 DEG C; The chemical component weight per-cent of described steel is: C:0.055%-0.095%, Si:0.15%-0.30%, Mn:1.50%-1.85%, P :≤0.020%, S :≤0.008%, Ti:0.010%-0.050%, Als:0.02%-0.06%, Nb:0.065%-0.07%, Cr:0.23%-0.31%, V:0.01%-0.04%, N :≤0.008%, all the other are Fe and inevitable impurity; Steel final state of the present invention is As rolled, and it is organized as ferrite, bainite and M/A mixed structure.