CN101928885B

CN101928885B - Hydrothion corrosion resistant pipe steel and production method thereof

Info

Publication number: CN101928885B
Application number: CN2009100336952A
Authority: CN
Inventors: 徐国利; 韩孝永; 唐洪乐; 齐志国; 韩乃川; 吴德润
Original assignee: Shanghai Meishan Iron and Steel Co Ltd
Current assignee: Shanghai Meishan Iron and Steel Co Ltd
Priority date: 2009-06-26
Filing date: 2009-06-26
Publication date: 2013-04-24
Anticipated expiration: 2029-06-26
Also published as: CN101928885A

Abstract

The invention relates to hydrothion corrosion resistant pipe steel and a production method thereof, belonging to the field of pipe steel production technology. The pipe steel comprises the following chemical components in percentage by mass: 0.05-0.10% of C, 0-0.35% of Si, 1.15-1.35% of Mn, 0-0.015% of P, 0-0.006% of S, 0.04-0.06% of Nb, 0.015-0.03% of Ti, 0.035-0.065% of V, 0.2-0.3% of Cu, 0.2-0.3 % of Ni, 0.015-0.02% of Al, and the balance of Fe and inevitable impurity elements. By the invention, the technical problems that the traditional hydrothion corrosion resistant pipe steel has lower toughness, poor matching effect of strength and plasticity, poor hydrothion corrosion resistance, and the like can be solved; and the steel of the invention has the advantages of high strength, excellent constant temperature and lower temperature impact toughness, and good properties of welding, molding, cold-bend, and the like, as well as excellent hydrothion corrosion resistance and is quite suitable for transmission pipes of oil, natural gas, and the like containing hydrothion media.

Description

Hydrothion corrosion resistant pipe steel and production method thereof

Technical field

The present invention relates to a kind of pipe line steel, especially a kind of hydrothion corrosion resistant pipe steel also relates to its production method simultaneously, belongs to pipe line steel manufacturing technology field.

Background technology

Pipeline is as the main transport agent of oil, Sweet natural gas etc., and its Operation safety has very important effect to the impact of the national economic development.Corrosion is the key factor that affects tubing system reliability and work-ing life, wherein H 2 S stress corrosion is one of important form of pipe line steel corrosion, it not only causes the leakage because of media such as the oil that perforation causes, gas, water, and tends to cause great financial loss, loss of life and personal injury, environmental pollution and oil gas to carry the accidents such as interruption.Studies show that, this corrosion failure is main because metallic substance is in the hydrogen sulfide containing medium, and the hydrogen of separating out in electrochemical corrosion course enters metallic substance inside and produces the notch cuttype crackle, and growing of these crackles finally makes the metallic substance cracking.Along with the high speed development of China's pipeline cause, the performance of pipe line steel is had higher requirement, particularly to have good hydrogen sulfide corrosion resistance energy.Owing to containing the hydrogen sulfide of higher concentration in the gas product of China, the hydrogen sulfide corrosion that produces is even more serious, can require the hydrogen sulfide corrosion resistance of steel for pipe higher, so produce have good hydrogen sulfide corrosion resistance can pipeline steel significant.

Retrieval finds, the Chinese patent application that number of patent application is 200580019466.5, name is called " low-alloy steel for oil well tube that has excellent sulfide stress cracking resistance " provides a kind of sleeve pipe or low-alloy steel for oil well tube pipeline, that have excellent sulfide stress cracking resistance that oil well or gas well are used that be applicable to.This low-alloy steel for oil well tube is in quality %, contain C:0.2～0.35%, Si:0.05～0.5%, Mn:0.05～1.0%, below the P:0.025%, below the S:0.01%, Al:0.005～0.10%, Cr:0.1～1.0%, Mo:0.5～1.0%, Ti:0.002～0.05%, V:0.05～0.3%, B:0.0001～0.005%, below the N:0.01%, O (oxygen): below 0.01%, Nb:0～0.1%, Ca:0～0.01%, Mg:0～0.01% and Zr:0～0.1%.Contain the elements such as Cr, Mo, B, Mg, Zr in these steel, cost is higher; In addition, [C] and carbon equivalent are higher in this invention material steel, and be unfavorable to the formability, weldability, toughness and the plasticity that improve steel, and the ballistic work numerical value of these steel is unlisted, although the intensity rank of material is higher, studies show that, the comprehensive mechanical performance of these steel needs to improve.

In addition, the Chinese patent application that application number is 00123185.5, name is called " a kind of Ultra-low carbon high tenacity anti-H 2 S steel for gas delivering pipeline " discloses a kind of Ultra-low carbon high tenacity anti-H 2 S usefulness X65 level steel for gas delivering pipeline, its main chemical compositions (% by weight) is C0.02～0.04%, and Si 0.15～0.35%, Mn1.4～1.6%, Nb0.03～0.05%, V0.02～0.04%, Mo0.2～0.4%, S＜0.0007%, P＜0.0030%, all the other are iron Fe.Except containing higher Mn element, also contain expensive Mo element in these steel, cost of alloy is higher; In addition, wherein C, S, P content are lower, have also correspondingly increased metallurgical cost; Analyze as can be known, the maximum ga(u)ge of these steel is 8 millimeters, and such as conveying high-pressure, high-density medium, its intensity and wall thickness are obviously not enough, and pipeline very easily causes rupture failure, poor stability, and its unit elongation is lower, only has 20.9-24.5%, and processing forming is bad.

Summary of the invention

The object of the invention is to: for the shortcoming of prior art existence, it is other high strength of 550MPa level, high tenacity hydrothion corrosion resistant pipe steel that a kind of yield strength is provided, provide simultaneously its manufacture method, the method adopts low-carbon (LC), low silicon and microalloy treatment technology, and utilize inclusion morphology control and roll control cooling technology to produce, thereby help to guarantee that steel of the present invention when having good hydrogen sulfide corrosion resistance energy, have the excellent comprehensive performances such as high strength, high tenacity, good welds performance, high performance-price ratio.

In order to reach above purpose, the applicant designs hydrothion corrosion resistant pipe steel chemical composition of the present invention (mass percent) as shown in table 1 by repetition test and continuous theoretical analysis.

Table 1 designing chemical composition (%)

C

Si

Mn

P

S

Nb

Ti

V

Cu

Ni

Alt

0.05 ～0.10

≤0.35

1.15 ～1.35

≤0.015

≤0.006

0.040 ～0.060

0.015 ～0.030

0.035 ～0.065

0.20 ～0.30

0.015 ～0.025

Surplus is Fe and inevitable impurity element.

In hydrothion corrosion resistant pipe steel of the present invention, the cause that each elemental composition is determined is as follows:

[carbon]: improve carbon content, favourable to the room temperature strength and the medium temperature intensity that improve steel, but all unfavorable to plasticity, toughness, formability, the weldability of steel.Increase along with carbon content, hydrogen induced cracking susceptibility increases, this is that reduction carbon and carbon equivalent can improve the hydrogen sulfide corrosion resistance energy of pipe line steel because the increase of carbon and carbon equivalent can make steel generate the martensitic stucture the most harmful to hydrogen blistering susceptibility under hot-rolled state in the pipe line steel.Therefore carbon content control is unsuitable too high.

[manganese]: add an amount of Mn in the pipe line steel, can improve the hardening capacity of steel pipe, play solution strengthening effect, remedy the strength degradation that low-carbon (LC) or Ultra-low carbon cause.The research discovery, the massfraction of C is the hot-rolled steel of 0.05%-0.15%, and the massfraction of Mn surpasses after 1.6%, and along with the massfraction increase of Mn, hydrogen induced cracking length increases, so the massfraction of pipe line steel Mn generally is limited to 0.8%-1.6%.

[silicon]: reduce silicone content, favourable to formability, weldability, toughness and the plasticity that improves steel, and can improve the Coating of steel.

[sulphur, phosphorus]: sulphur forms sulfide inclusion in steel, makes its ductility and toughness drop.During steel rolling, because MnS is mingled with along with rolling direction is extended, the anisotropy of steel is increased the weight of, cause Laminated steel when serious.The high steel resistance to corrosion of sulphur content greatly reduces simultaneously, and S can promote hydrogen induced cracking to occur, and the S content of body material is higher, more easily produces hydrogen induced cracking.The high cold shortness that increases steel of phosphorus rises the brittle transition temperature of steel, and the impelling strength of steel is significantly descended, and the segregation of P also impels hydrogen induced cracking to form, and the content that reduces P can obviously improve the anti-Hydrogen induced cracking performance of steel.

[titanium]: add trace amount of titanium in the steel, not only be conducive to the deoxidation of steel, and owing to the nitride of titanium in the steel or the existence of carbide, can play the recrystallize that postpones austenite crystal and the tendency of growing up, thereby improve performance, the especially impelling strength of steel.Ti can also the Effective Raise welding property.Crystal grain was too grown up when TiN can effectively prevent heating of plate blank.

[niobium]: in steel, form nitride or carbide, be conducive to the crystal grain thinning tissue, the effect of performance precipitation strength.

[vanadium]: in steel, form carbide, the effect of performance precipitation strength, the obdurability of raising steel.In addition, the compound adding of niobium, vanadium, titanium, more remarkable than adding separately separately effect, not only greatly improve intensity and the toughness of steel, and strengthened pipe line steel hydrogen sulfide corrosion resistance energy.

[copper]: add reasonable quality Cu hydrogen induced cracking susceptibility is obviously reduced.Because Cu can promote the steel surface to form passive film (asking chemical structure still among research), reduced the intrusion of hydrogen, thereby stoped the formation of hydrogen induced cracking.Cu can also offset the deleterious effect of S in the steel, and the Cu in the steel is combined with the S element can produce sulfide hard to tolerate, thereby has weakened S to the corrosion proof deleterious effect of steel.

[nickel]: nickel can improve the low-temperature flexibility of the toughness of steel, particularly steel, and nickel can also improve the red brittleness that copper easily causes in steel simultaneously.

In a word, hydrothion corrosion resistant pipe steel of the present invention has adopted low-carbon (LC), low silicon to relate to, with manganese as strengthening element, carry out deoxidation with aluminium, and adopt niobium, vanadium, titanium micro-alloyed intensive treatment, add especially in right amount the elements such as copper, nickel, the passive film that utilizes Cu to form, suppress the intrusion of hydrogen, form simultaneously the deleterious effect that sulfide is offset S; Moreover, the present invention also by adding the nickel composition, when improving steel toughness, improves hot-short that copper easily causes in steel.The result, solved existing hydrothion corrosion resistant pipe steel toughness on the low side, and intensity and plasticity can not matched well, the technical problems such as hydrogen sulfide corrosion resistance is relatively poor, make steel of the present invention except having the performances such as high strength, good normal temperature and low-temperature impact toughness and good welding, moulding, clod wash, also have the good performances such as hydrogen sulfide corrosion resistant, extremely be suitable for the line of pipes that oil, Sweet natural gas etc. contain hydrogen sulfide medium.

The production method of high-intensity high-tenacity hydrothion corrosion resistant pipe steel of the present invention adopts molten iron pre-desulfurization, converter top bottom blowing; blow Ar station (or LF stove---Ladel Furnace ladle refining furnace) and guarantee that bottom blowing Ar churning time was greater than 5 minutes; the RH stove carries out trimming, vacuum circulation degassing is processed; continuous casting adopts low-carbon steel protecting slag; whole process is blown the Ar protective casting, obtains the hydrothion corrosion resistant pipe steel slab of table 1 chemical composition.Its processing step is: desulfurizing iron pre-treatment → skim → converter smelting → Argon station or LF stove refining → RH (Ruhrstahland Heraeus vacuum circulation degassing method) refining → continuous casting.

The hot rolling technology method of above-mentioned hydrothion corrosion resistant pipe steel is, the continuous casting steel billet that mentioned component is required is heated to 1210 ℃～1250 ℃, hot rolling is divided into the two-part rolling technology, and roughing is rolling more than recrystallization temperature, and finish rolling is rolling in non-recrystallization temperature interval.Rough rolling step is 5 passage tandem rollings, and the roughing end temp is 1000 ℃～1100 ℃.Finish rolling is 7 passage tandem rollings, and the finish rolling start rolling temperature is 900 ℃～950 ℃, and the finish rolling end temp is 820 ℃～860 ℃.Finish rolling stage compression ratio is greater than 80%, and after the finish rolling, the steel plate finished product thickness is 3～12mm, and the laminar flow cooling stages adopts the leading portion cooling, and coiling temperature is 500 ℃～600 ℃.

Description of drawings

The present invention is further illustrated below in conjunction with accompanying drawing.

Fig. 1 is the metallographic microstructure photo of hydrothion corrosion resistant pipe steel of the present invention.

Embodiment

The present invention will be further described below in conjunction with embodiment 1-3.

Following table 2 is the component proportion of various embodiments of the present invention, the component % that is weight percentage, and surplus is Fe.

Table 2 embodiment 1-3 chemical composition (%)

Element	C	Si	Mn	P	S	Nb	Ti	V	Cu	Ni	Alt
												Design	0.05 ～0.10	≤0.35	1.15 ～1.35	≤0.015	≤0.006	0.040 ～0.060	0.015 ～0.030	0.035 ～0.065	0.20 ～0.30	0.20 ～0.30	0.015 ～0.025
Embodiment one	0.06	0.26	1.26	0.012	0.003	0.048	0.020	0.045	0.26	0.22	0.020
												Embodiment two	0.08	0.22	1.23	0.010	0.0025	0.046	0.018	0.041	0.23	0.26	0.019
Embodiment three	0.09	0.23	1.30	0.010	0.003	0.045	0.022	0.046	0.25	0.25	0.022

Requirement according to steel product ingredient design of the present invention; adopt molten iron pre-desulfurization; the converter top bottom blowing; blow Ar station (or LF stove) and guarantee bottom blowing Ar churning time greater than 5 minutes, the RH stove carries out trimming, vacuum circulation degassing is processed, and guarantees that the pure degassed time of RH was greater than 8 minutes; feed simultaneously an amount of iron-calcium line; continuous casting adopts low-carbon steel protecting slag, and whole process is blown the Ar protective casting, is cast into the thick continuous casting steel billet of 210mm.

Its concrete technology step is: desulfurizing iron pre-treatment → skim → converter smelting → Argon Ar station or LF stove refining → RH refining → continuous casting (parameter control sees Table 3).

Molten iron pre-desulfurization: sweetening agent adds lime powder (CaO) by magnesium powder (Mg) and forms, molten steel per ton uses 0.8 kilogram in magnesium powder (Mg), 3.2 kilograms of lime powders (CaO), after the molten iron pre-desulfurization, sulphur content is 0.002% in the molten steel, then desulfurization slag is removed totally.

Converter smelting: whole smelting process is carried out whole process bottom blowing argon gas, molten steel is fully stirred, so that composition and the temperature of even molten steel, and the content of the nitrogen in the reduction molten steel, hydrogen and inclusion, converter terminal C content is 0.03-0.05%, P content≤0.010%, adopt the two pushing off the slag operations of slag retaining cap and slag-blocking ball during tapping, the lower quantity of slag of strict control, in case rephosphorization, the tapping time is greater than 5min.

Argon Ar station or the refining of LF stove: the Stirring by Ar Blowing time was greater than 5 minutes, so that composition and the temperature of even molten steel, and the content of nitrogen, hydrogen and inclusion in the reduction molten steel.

The RH vacuum refinement: the pure degassed time was reduced the content of nitrogen, hydrogen and inclusion in the molten steel greater than 8 minutes.

Continuous casting: adopt low-carbon steel protecting slag, prevent molten steel recarburization, continuous casting whole process is blown the Ar protective casting, prevents the air-breathing and secondary oxidation of molten steel.

Table 3 embodiment of the invention 1-3 process for making control parameter

The steel-making parameter	Magnesium powder (kg/ t)	Lime powder (kg/t)	Sulphur content after the desulfurization (%)	Converter whole process bottom Argon	Converter terminal C content (%)	Converter terminal P content (%)	Two pushing off the slag	The tapping time (dividing)	Argon Ar station or LF stove blow the Ar time (dividing)	The pure degassed time of RH (dividing)	Continuous casting whole process is blown Ar
												Embodiment one	0.8	3.2	0.002	Adopt	0.05	0.009	Adopt	5	8	9	Adopt
Embodiment two	0.8	3.2	0.002	Adopt	0.03	0.007	Adopt	6	8	10	Adopt
												Embodiment three	0.8	3.2	0.002	Adopt	0.04	0.009	Adopt	6	8	10	Adopt

Continuous casting steel billet is after process furnace reheats, rolling on the Continuous Heat tandem rolling mill, technology controlling and process sees Table 4, by roughing milling train and finish rolling tandem rolling unit after recrystallization zone and the controlled rolling of non-recrystallization district, control cooling, then batch, produce qualified hot-rolled sheet coil, product thickness is 3-12mm.

Table 4 embodiment of the invention 1-3 hot rolling technology control parameter

Hot Rolling Parameters	Slab heating temperature/℃	The roughing end temp/℃	Finish rolling begin temperature/℃	The finish rolling end temp/℃	Finish rolling compression ratio/%	Coiling temperature/℃
							Set	1210-1250	1000-1100	900-950	820-860	≥80	500-600
Embodiment one	1230	1050	950	850	85	570
							Embodiment two	1210	1030	920	830	83	560
Embodiment three	1220	1020	910	830	80	560

The hydrogen sulfide corrosion resistant pipeline hot-rolled sheet coil that utilizes aforesaid method to obtain, microstructure is that ferrite adds a small amount of perlite, grain fineness number is (referring to Fig. 1) more than 10 grades, except having high strength, also has good low-temperature impact toughness and good welding, moulding, processing characteristics.Yield strength 〉=550MPa, tensile strength 〉=630MPa, elongation after fracture 〉=30%, steel plate is-20 ℃ of Charpy-V impact power 〉=200J laterally, and hydrogen sulfide corrosion resistant experiment flawless produces.Sampling detects mechanical property and the hydrogen sulfide corrosion resistant ability sees Table 5: as can be seen from Table 5, mechanical property and hydrogen sulfide corrosion resistant ability all obviously are better than high-strength line-pipe steel X65 and high-strength structure steel Q460.

The mechanical property contrast table of table 5 coiled sheet sampling

Performance index	Yield strength/MPa	Tensile strength/MPa	Elongation after fracture/%	-20℃ Akv/J	180 ° of pliability test d=2a	NACETM 0284 solution A
							Embodiment one	565	630	36	235	Intact	Flawless
Embodiment two	570	655	33	220	Intact	Flawless
							Embodiment three	585	670	31	205	Intact	Flawless
X65	490	580	29	85	Intact	Crackle is arranged
							Q460	470	590	23	120	Intact	Crackle is arranged

In a word, the present invention is on the basis of general C-Mn composition of steel, by reducing C, Si content, compound interpolation strengthening element Nb, the microalloy elements such as V, Ti, and add in right amount the elements such as copper, nickel, and adopting low temperature finish to gauge, the production technique such as quick cooling are produced, the yield strength index of coiled sheet is reached more than the 550MPa, and have good hydrogen sulfide corrosion resistance energy.Contrast as can be known, the constituent content controls such as C, Mn, S, P are moderate in the steel of the present invention, carbon content is relatively low, by the content of further control steel interalloy element, has not only improved formability, weldability, toughness and the plasticity of steel, and has a good hydrogen sulfide corrosion resistance energy, steel yield strength of the present invention is greater than 550MPa, and tensile strength is greater than 630MPa, and-20 ℃ of V-type ballistic works are greater than 200J, elongation after fracture is greater than 30J, and hydrogen sulfide corrosion resistant experiment flawless produces.Its characteristics are summarized as follows:

1 steel of the present invention have good comprehensive mechanical property, the yield strength index reaches more than the 550MPa, and steel plate is-20 ℃ of Charpy-V impact power 〉=200J laterally, and intensity and plasticity are better mated, be fit to the design of steel plate attenuate, thereby reduced the production cost of the line of pipes such as oil, Sweet natural gas; Because this material has good low-temperature impact toughness, be fit to use under the various envrionment conditionss.

2 steel of the present invention have good hydrogen sulfide corrosion resistance energy, have prolonged the work-ing life of the line of pipes such as oil, Sweet natural gas, have reduced in the past the line of pipes such as oil, Sweet natural gas because of the generation of corrosion accident.

3 steel of the present invention have good welding property, by reasonable component design and welding material recommendation, can the Effective Raise welding efficiency, and obtain good property of welded joint.

4 steel of the present invention adopt cooling controlling and rolling controlling process production, with hot-rolled state delivery, need not to heat-treat, and production technique is simple, and production cost is lower, and this technology can more easily be generalized to other relevant enterprises.

In addition to the implementation, the present invention can also have other embodiments.All employings are equal to the technical scheme of replacement or equivalent transformation formation, all drop on the protection domain of requirement of the present invention.

Claims

1. hydrothion corrosion resistant pipe steel is characterized in that containing the chemical composition of following mass percent:

C 0.05-0.10％，Si 0-0.35％，Mn 1.15-1.35％，P 0-0.015％，

S 0-0.006％，Nb 0.04-0.06％，Ti 0.015-0.03％，V0.035-0.065％，

Cu 0.2-0.3％，Ni 0.2-0.3％，Al 0.015-0.02％，

Surplus is Fe and inevitable impurity element.

2. the production method of described hydrothion corrosion resistant pipe steel according to claim 1 is characterized in that may further comprise the steps: desulfurizing iron pre-treatment → skim → converter smelting → Argon station or LF stove refining → RH refining → continuous casting.

3. the production method of described hydrothion corrosion resistant pipe steel according to claim 2, it is characterized in that: the sweetening agent in the described desulfurizing iron pre-treatment step adds lime powder by the magnesium powder and forms, and molten steel per ton uses 0.8 kilogram in magnesium powder, 3.2 kilograms of lime powders.

4. the production method of described hydrothion corrosion resistant pipe steel according to claim 3, it is characterized in that: in the described converter smelting step, carry out whole process bottom blowing argon gas, molten steel is fully stirred, the mass percentage content of converter terminal C is controlled at 0.03-0.05%, and the mass percentage content of P is controlled at≤and 0.01%.

5. the production method of described hydrothion corrosion resistant pipe steel according to claim 2, it is characterized in that: the heating of plate blank to 1210 that described continuous casting is obtained ℃～1250 ℃, hot rolling is divided into two sections of roughing and finish rolling, described roughing is rolling more than recrystallization temperature, and described finish rolling is rolling in non-recrystallization temperature interval.

6. the production method of described hydrothion corrosion resistant pipe steel according to claim 5, it is characterized in that: described rough rolling step is 5 passage tandem rollings, the roughing end temp is 1000 ℃～1100 ℃; Described finish rolling is 7 passage tandem rollings, and the finish rolling start rolling temperature is 900 ℃～950 ℃, and the finish rolling end temp is 820 ℃～860 ℃.

7. the production method of described hydrothion corrosion resistant pipe steel according to claim 6, it is characterized in that: described finish rolling stage compression ratio is greater than 80%, the steel plate finished product thickness is 3～12mm after the finish rolling, and the laminar flow cooling stages adopts the leading portion cooling, and coiling temperature is 500 ℃～600 ℃.