CN105463334A - Manufacturing process of oil casing steel - Google Patents

Abstract

The present invention relates to an oil casing steel and a manufacturing process thereof. The method is as below: heating a tube blank obtained from continuous casting or continuous rolling by a continuous furnace, punching by a punching machine, rolling the tube at the temperature of 950-1050 DEG C, removing rod, sending the tube into a reheating furnace, insulating at 800-1000 DEG C, sending the tube into a stretch-reducing mill or a stretching machine, rolling and air-cooling, then quenching at 860-1000 DEG C, and then insulating at 600-660 DEG C for tempering, so as to obtain a finished tube. The steel of the present invention has good hardenability and high structural stability, and fully guarantees that the oil casing for oil well reaches yield strength of 1000-1200 MPa and satisfies the requirements of lateral impact energy greater than 70J, and impact energy greater than 90J.

Description

A kind of manufacturing process of oil bushing steel

Technical field

The present invention relates to a kind of oil annular tube steel, i.e. the oil bushing steel of high-intensity high-tenacity, particularly relate to a kind of at well depth

Exceed 5000m or anti-squeeze performance requriements high condition under, yield strength is at more than 1000Mpa and the chemical composition of the oil annular tube steel that transverse impact merit is greater than 75J, ballistic work is greater than more than 90J and manufacturing process thereof.

Background technology

With regard to tubing and casing normal steels, the maximum intensity of API standard is Q125 grade of steel, and impact of collision merit is greater than 60J.

Along with the change of oilfield exploitation condition, the deep-well of exploitation oil gas is more and more darker, and Q125 grade of steel conventional oil sleeve pipe can not meet needs, needs the intensity more better tubing and casing of high tenacity.Along with the intensity of tubing and casing improves constantly, toughness can constantly decline, and because oil-gas field drill condition is day by day harsh, the exploitation of deep-well is increasing, and formation downhole change also becomes increasingly complex, and therefore needs to adopt to have that intensity is high, the material of good toughness.At present, develop 150Ksi tubing and casing material in the world, mainly added lower temperature tempering by shrend, reach required performance.But, because high-intensity high-tenacity tubing and casing belongs to the product that in oil well pipe product, production difficulty is large, added value is high, domesticly substantially can not to produce.Therefore many oil fields still adopt P110 or Q125 grade of steel to increase the thick way of arm to maintain use, and ubiquity ultra deep well can not development problem.

The production difficulty of high-intensity high-tenacity pipe is its high and toughness reguirements and have comprehensively to requirement of strength

Performance has very high requirement.

Affect the principal element alloy content of material high-strong toughness performance, the amount of inclusions and form and thermal treatment process,

The alloy content of material is high, and intensity is higher, simultaneously the poor toughness of material; The alloy content of material is low, and intensity is lower, and the toughness of material is higher simultaneously.The purity of steel can improve the toughness of material, and the amount of inclusions is more and form is more irregular, segregation is more serious, toughness is poorer.

The quantity of inclusion and form can be controlled by smelting and Calcium treatment.Alloy content mainly through control C,

The elements such as Mn, Cr, Mo, V, C content is high, can ensure to improve intensity, toughness can be caused simultaneously to decline, and can improve the cracking sensitivity of material.But along with the reduction of carbon content, the intensity of material also can reduce.For ensureing to obtain enough intensity under the condition of low carbon content.By the reasonable coordination of Mn, Cr, Mo, V element and C element, ensured the intensity of material by the method for Tempering and Quenching.Tempering and Quenching adopts quenching to increase temperature the method for tempering, remains on more than certain temperature and carries out tempering, ensure high strength and the high tenacity of material.In the production process of steel pipe, for solving high strength and this problem of high tenacity, many producers have all selected low C, high Cr, Ni produce high intensity oil casing tube by the mode of Tempering and Quenching.Low C can

To ensure the toughness of material, add by heavy alloyed the intensity ensureing that material is enough, then reached high strength and the high tenacity of material by Tempering and Quenching.Some producers adopts low alloy steel material to produce high intensity oil casing tube, finally abandons producing because the impelling strength of material is low or intensity is low.

Adopt high Cr, Ni alloy to carry out Tempering and Quenching again, the properties of material guarantees to reach high-strong toughness,

But for the sleeve pipe that produces oil relative to low alloy steel, considerably increase production cost, can the competitiveness of product in market be reduced.

Summary of the invention

The present invention proposes the seamless tubing and casing new steel grade of a kind of oil well low-alloy high-strength and manufacturing process thereof, rolls at steel pipe

Tempering and Quenching is carried out after system.Just can ensure under quality adjustment condition oil well tubing and casing reaching 1000 ~ 1200MPa and bend _ _ take intensity while can meet the requirement that transverse impact merit is greater than 70J, ballistic work is greater than more than 90J again.

Oil bushing steel of the present invention, its composition is as follows:

C：0.28～0.35wt％

Si：0.1～0.4wt％

Mn：0.8～1.6wt％

Mo：0.4～0.6wt％

Cr：0.8～1.2wt％

V：0.05～0.10wt％

S：≤0.005wt％

Al：0.01～0.04％

All the other are Fe and inevitable impurity.

Introduce each alloys producing respectively below:

C:0.28 ~ 0.35% (wt%, following element is identical), C is carbide forming element, the intensity of steel and the permeability that declines can be improved, time too low, the intensity of steel obviously reduces, and too Gao Shihui reduces the toughness of steel greatly, also can increase the cracking sensitivity of steel simultaneously.

Mn:1.0 ~ 1.6, Mn is austenite former, can improve the intensity of steel, acts on not obvious when content is less than 1.0, and when content is greater than 1.6, microstructure segregation tendency increases the weight of, the homogeneity of impact tissue.

Mo:0.4 ~ 0.6%: mainly improve the intensity of steel by carbide and solution strengthening form and improve steel belt roof bolt stability, too high levels can reduce the toughness of steel.

V:0.05 ~ 0.10, can crystal grain thinning, forms carbide, improves intensity and the toughness of steel.But when content reaches a certain amount of, its effect increase is just not obvious.

Si:0.1 ~ 0.4, can strengthen matrix, lower than 0.1, and DeGrain.But after content reaches more than 0.4, effect increase is just not obvious.

S :≤0.005%, add-on exceedes can increase sulfide content, affects the toughness of steel.

Al: adding appropriate Al can the crystal grain of refinement steel, but add-on more than 0.4% after can worsen the mechanical property of steel.

The manufacturing process of this oil bushing steel is as follows:

After pipe through electrosmelting casting heats through rotary heating furnace, tapping machine is bored a hole, then at 950 ~ 1050 DEG C

Carry out tube rolling, open tube enters reheating furnace after taking off rod, and holding temperature is between 800 ~ 1000 DEG C, and mainly reaustenitizing steel pipe is more yielding for its object, and tissue obtains further refinement.Steel pipe is air cooling after stretch-reducing mill rolling, subsequently again 860 ~ 1000 DEG C of temperature ranges carry out austenitizing and water quenching to obtain oversaturated martensitic stucture, then steel pipe carries out modifier treatment to obtain evenly tiny tempered sorbite tissue 600 DEG C ~ 660 DEG C insulations, finally guarantees that the mechanical property of steel pipe reaches 150 grade of steel levels and makes production tube.

Steel grade of the present invention, has good hardening capacity and higher structure stability, can ensure at Tempering and Quenching

After have the close grain of more than 8 grades.Requirement of strength required for complete energy ensures and toughness reguirements.The present invention, except controlling carbon content and adding except suitable Cr, Mo, V, Mn, Al guarantee mechanical property, also improves the toughness of steel by smelting Technology for Clean Steel.

Adopt the element of crystal grain thinning, utilize the hardening capacity of material to carry out complete marquench, then control the final performance of material by controlling tempering temperature, its performance inconsistency is less than 20MPa, meets the requirement of ultra-deep oil well to tubing and casing performance completely.

Embodiment

The pipe obtained by continuous casting or tandem rolling is after rotary heating furnace heating, and perforated machine is bored a hole, then 950 ~

1050 DEG C of tube rollings, enter reheating furnace after de-rod, after 800 ~ 1000 DEG C of insulations, enter stretch-reducing mill or elongator rolls rear air cooling, then 860 ~ 1000 DEG C of insulations are quenched, and then carry out tempering 600 DEG C ~ 660 DEG C insulations and make production tube.

Claims (1)

1. a manufacturing process for oil bushing steel, is characterized in that smelting by following composition:

C：0.28～0.35wt％

Si：0.1～0.4wt％

Mn：0.8～1.6wt％

Mo：0.4～0.6wt％

Cr：0.8～1.2wt％

V：0.05～0.10wt％

S：≤0.005wt％

Al：0.01～0.04％

All the other are Fe and inevitable impurity; The pipe obtained by continuous casting or tandem rolling is after process furnace heating, perforated machine is bored a hole, then at 950 ~ 1050 DEG C of tube rollings, reheating furnace is entered after de-rod, after 800 ~ 1000 DEG C of insulations, enter stretch-reducing mill or elongator rolls rear air cooling, then 860 ~ 1000 DEG C of insulations are quenched, and then carry out tempering 600 ~ 660 DEG C of insulations and make production tube.