CN102828121A

CN102828121A - K55-grade high frequency resistance welding oil casting steel and its manufacturing method

Info

Publication number: CN102828121A
Application number: CN2011101601191A
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: 2012-12-19
Anticipated expiration: 2031-06-14
Also published as: CN102828121B

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 method of manufacture thereof

Technical field

The present invention relates to a kind of HFW (High frequency electric-resistance-weld; High frequency resistance welding) casing steel technology; Be particularly related to and a kind ofly among the API SPEC 5CT have superior weldability and impelling strength (10 ℃, low yield strength ratio K55 steel level oil bushing laterally＞100J) is with steel and method of manufacture thereof.

Background technology

Petroleum casing pipe is one of the most frequently used oil country tubular good in oil field, and consumption is big, and it is many to spend, and is requisite construction material in the oil-gas field drill operation.The HFW sleeve pipe is compared with seamless tube, has that wall thickness is even, dimensional precision is high, the perforation performance is good, anti-squeezing ruin significant advantages such as ability is strong, cost is low, substitutes traditional weldless steel tube gradually.

API Spec 5CT regulation: the ys of K55 rank steel pipe is between 379-552MPa; Tensile strength >=655MPa, elongation >=20%, ballistic work does not have mandatory requirement; Can select (21 ℃ of Akv; Laterally) >=and 20J, the raising that Along with people's requires oilfield safety proposes certain requirement to the impact property of raw material steel band.

At present, K55 level HFW telescopic production technique is: high-carbon design (＞0.15%) is adopted in composition design, and the interpolation Alloy Elements Mo that has is smelted and is rolled into hot rolled strip; Then, steel band is processed welded tube through the HFW mode, and butt welded seam or steel pipe integral heat-treat, subsequently pipe end is carried out suitable screw thread processing, final production goes out qualified K55 rank petroleum casing pipe.Owing to carbon content higher (＞0.15%), can't obtain the hot rolled strip of excellent weldability, not only improve the complex process degree of HFW tubulation, and reduced the production efficiency of tubulation; Higher carbon content also causes the impelling strength of steel band general simultaneously.

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

The paper of the Chinese patent (CN101328559A) of the Chinese patent (CN101270438A) of " the low yield strength ratio electric resistance welding petroleum overlaps effective normalized steel, resistance welding sleeve pipe and method for making thereof " by name, " low yield strength ratio oil casing pipe steel, petroleum casing pipe and method for making thereof " by name and " 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%; Unfavorable to weldableness and toughness; And need homogeneous tube to heat-treat behind the tubulation, and complex process, production cost is high.

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

See that from above disclosed document prior art C content is all than higher, the weldableness and the impelling strength of steel band are general, and weldprocedure is complicated, and tubulation production efficiency is low; The needs that have add valuable Alloy Elements Mo, and cost of alloy is higher; The needs that have carry out homogeneous tube thermal treatment, and thermal treatment process is complicated, and the steel pipe's production cost is high.

Summary of the invention

It is not enough to the objective of the invention is to overcome above-mentioned existing in prior technology, and a kind of employing low-carbon (LC) design is provided, have superior weldability and impelling strength (10 ℃, horizontal＞100J) low yield strength ratio K55 level HFW oil casing steel and method of manufacture thereof.

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 unavoidable impurities.

C: carbon is carbide forming element; Improve the intensity of steel through solution strengthening and precipitation strength effect; Be the effective element of proof strength, but the too high welding property and the impelling strength that will influence product of carbon content, it is comparatively suitable that carbon is controlled at 0.055%-0.095%.

Si: silicon can play the 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 the solution strengthening effect, can also increase stabilization of austenite, and is also favourable to improving hardening capacity, effectively guarantees the intensity of steel.But manganese content is excessive, can increase the center segregation tendency of continuously cast bloom, influences the homogeneity of structure of hot-strip, brings negative impact to weldquality, and suitable scope is 1.50%-1.85%.

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

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

Nb: niobium is thin brilliant and precipitation strength element, can remedy the decline that reduces the intensity that causes because of carbon, improves welding property, but too high meeting increases cost of alloy, and suitable scope is 0.04%-0.07%.

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

Ti: titanium is strong carbonitride forming element, and significantly refine austenite crystal grain can remedy the decline that reduces the intensity that causes because of carbon.Content is too high, is prone to form thick TiN, reduces material property, and suitable scope is 0.010%-0.050%.

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

Als: aluminium is the reductor of using always, in steel, adds a spot of aluminium, but crystal grain thinning improves impelling strength, and suitable scope is 0.02%-0.06%.

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

The method of manufacture 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) smelts continuous casting process: 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 and handle with the control inclusion morphology and improve ductility, toughness and the cold-bending property of steel, sheet billet continuous casting process continuous casting steel billet-continuous casting adopt induction stirring or dynamically gently depress, with the quality of raising continuous casting steel billet.

2) rolling technology: continuous casting steel billet is heated to 1200-1300 ℃ through process furnace, carries out the controlled rolling of two stages at the short flow process hot continuous rolling of 2150ASP unit subsequently, and the fs start rolling temperature is 1100-1200 ℃, and finishing temperature is greater than 980 ℃; The subordinate phase start rolling temperature is less than 960 ℃, and finishing temperature is 820-880 ℃; Steel band after rolling with first slow cooling after the fast two cold stage types of cooling cool off, the slow cooling section is cooled to 770-810 ℃ with speed of cooling 3-6 ℃/s; Fast cold section speed of cooling is 10-15 ℃/s, carries out steel band 570-630 ℃ of temperature and batches.Roll the slow cooling of back steel band elder generation, guarantee that steel band has the soft phase constitution of a certain amount of proeutectoid ferrite, while crystal grain has to a certain degree grows up, and has reduced ys; And then adopt cooling fast, and obtain the hard phase constitution of tiny bainite and M/A, have high tensile strength, thereby guaranteed 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 ℃, laterally＞100J); 2) replace noble element Mo with a small amount of Cr, V, practice thrift cost of alloy; 3) only need butt welded seam and heat affected zone to heat-treat behind the steel band tubulation, do not need homogeneous tube thermal treatment, thermal treatment process is simple, and the steel pipe's production cost is low.

Embodiment

Through embodiment the present invention is done further description below.

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

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

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 invention steel, rolling and process for cooling

The mechanical property of table 3 embodiment of the invention steel

Visible by table 3, as to adopt composition design of the present invention and rolling technology to produce low yield strength ratio HFW oil casing pipe steel can satisfy the requirement of API SPEC 5CT standard to K55 level steel pipe.

Claims

1. a K55 level high-frequency electric resistance welded petroleum casing pipe steel is characterized in that the chemical component weight per-cent of 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:0.04%-0.07%, Cr:0.23%-0.31%; V:0.01%-0.04%, N :≤0.008%, all the other are Fe and unavoidable impurities.

2. the method for manufacture of the said K55 level of claim 1 a 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 ℃ through process furnace; Carry out the controlled rolling of two stages at short flow process hot continuous rolling unit subsequently, the fs start rolling temperature is 1100-1200 ℃, and finishing temperature is greater than 980 ℃; The subordinate phase start rolling temperature is less than 960 ℃, and finishing temperature is 820-880 ℃; Roll the back steel band and cool off with two stage manner, the slow cooling section is cooled to 770-810 ℃ with 3-6 ℃/s speed of cooling, and fast cold section speed of cooling is 10-15 ℃/s, and coiling temperature is 570-630 ℃.