CN103205646A

CN103205646A - Seamless steel pipe for G-class high-tenacity drill pipe body

Info

Publication number: CN103205646A
Application number: CN2013101246466A
Authority: CN
Inventors: 董珍; 何建中; 刘金; 贺景春; 姜海龙; 王金龙
Original assignee: Baotou Iron and Steel Group Co Ltd
Current assignee: Baotou Iron and Steel Group Co Ltd; Inner Mongolia Baotou Steel Union Co Ltd
Priority date: 2013-04-11
Filing date: 2013-04-11
Publication date: 2013-07-17

Abstract

The invention relates to a seamless steel pipe for a G-class high-tenacity drill pipe body. The seamless steel pipe comprises the following chemical components by mass percent: 0.20-0.30wt% of C, 0.15-0.35% of Si, 1.00-1.30wt% of Mn, less than or equal to 0.013wt% of P, less than or equal to 0.005wt% of S, 0.80-1.10wt% of Cr, 0.20-0.40wt% of Mo, less than or equal to 0.040wt% of Al, less than or equal to 0.010wt% of As+Sn+Pb+Sb+Bi, less than or equal to 0.002wt% of O, less than or equal to 0.006wt% of N, less tan or equal to 0.0002wt% of H, and the balance of Fe and unremovable trace elements; and the sum of the mass percentages is 100%. The seamless steel pipe for the G-class high-tenacity drill pipe body is characterized in that the impact toughness of the G-class high-tenacity drill pipe body is greatly improved while the standard required yield strength, strength of extension and elongation indicator are satisfied; as a result, the use safety of the drill pipe is improved and the service life of the drill pipe is prolonged.

Description

A kind of G grade high ductility drill pipe body weldless steel tube

Technical field

The present invention relates to a kind of G grade high ductility drill pipe body weldless steel tube, belong to the metallurgical material field.

Background technology

Drilling rod be connect drill bit in the boring bar tool, in order to the rod member of transferring power, be a large amount of strength members that use in the petroleum drilling and mining industry, the quality of its performance is directly connected to the success or not of drilling operation.In recent years, development along with oil field prospecting, the exploration in east China area is to deep layer, seabeach, shallow sea development, western Tarim Basin, tell oil field such as Kazakhstan because occurring deep-well, ultra deep well and high-pressure gas well in a large number, geological condition and corrosive medium situation are more complicated, along with the increase of drilling depth, and the increasing of marine oil gas field exploitation dynamics, to having higher requirement in the internal soundness of oil drill rocker, mechanical property, work-ing life etc.At present, summer to drill pipe body in the API Spec 5DP standard requires index (average absorption ballistic work 〉=43J, minimum absorption ballistic work 〉=38J on the low side than absorbing ballistic work, test temperature is 21 ℃ ± 3 ℃, specimen size is 10mm * 7.5mm * 55mm, v-notch is vertical), far can not satisfy in the severe environment operations such as oil field prospecting deep-well, ultra deep well, high-pressure gas well, thermal recovery well the demand to the high tenacity drilling rod, therefore, the exploitation of high tenacity drilling rod will have wide production and market outlook.

Summary of the invention

The objective of the invention is based on above technical background, provide a kind of composition reasonable in design, guarantee that its yield strength reaches between 724MPa～931MPa, under the index condition of tensile strength 〉=793MPa, elongation 〉=16%, average absorption ballistic work 〉=100J, minimum absorption ballistic work 〉=100J(test temperature are 21 ℃ ± 3 ℃; Specimen size is 10mm * 7.5mm * 55mm, vertically, v-notch), satisfy in the severe environment operations such as oil field prospecting deep-well, ultra deep well, high-pressure gas well, thermal recovery well the G grade high ductility drill pipe body weldless steel tube to the demand of high tenacity drilling rod.

For achieving the above object, the technical solution used in the present invention is:

A kind of G grade high ductility drill pipe body weldless steel tube, the quality percentage chemical ingredients of weldless steel tube material is: C 0.20～0.30; Si 0.15～0.35; Mn 1.00～1.30; P≤0.013; S≤0.005; Cr 0.80～1.10; Mo 0.20～0.40; Al≤0.040; As+Sn+Pb+Sb+Bi≤0.010; O≤0.002; N≤0.006; H≤0.0002; All the other are Fe and the trace elements that can not remove, and mass percent amounts to 100%.

The production method of this weldless steel tube is to adopt molten iron and steel scrap to do raw material, through hot metal pretreatment → top and bottom combined blown converter smelting → LF external refining → VD vacuum outgas → round billet continuous casting, obtain circular pipe blank, grow, weigh, spray mark → warehouse-in through a heating → perforation → tube rolling → tube reducing or sizing → cold bed cooling → sawing → aligning → flaw detection → hand inspection → survey again, to justify base and be rolled into weldless steel tube, and after the steel pipe total length carried out 880 ℃～920 ℃ quenchings and add the heat treatment quenching and tempering of 620 ℃～660 ℃ of tempering, make high tenacity drill pipe body weldless steel tube.

The design considerations of principal element content range is in the above-mentioned chemical ingredients:

The tissue of the carbon steel of C and performance have very big influence, are the primary control elements of intensity and hardness.Along with the increase of carbon content in the steel, the yield strength of steel, tensile strength, hardness and fragility increase.Take all factors into consideration intensity and the impelling strength of drill pipe body, the control of C content is more suitable 0.20%～0.30%.

The main effect of Cr is the hardening capacity that improves steel, makes steel have better comprehensive mechanical property after quenching, tempering.It can improve intensity, hardness and the wear resistance of steel, can improve oxidation-resistance and the erosion resistance of steel again, but also can improve the brittle transition temperature of steel.Therefore, the control of Cr content is advisable 0.80%～1.10%.

Mo energy crystal grain thinning, improve hardening capacity and the heat resistance of steel, when high temperature, can make steel keep enough intensity and creep resisting abilities, can improve the mechanical property of steel, the temper brittleness that suppresses steel alloy, but because the price of Mo is higher, therefore, take all factors into consideration performance and the Financial cost of steel, Mo content is controlled 0.20%～0.40%.

P is harmful elements to most steel grades, and P content height can cause steel " cold short " in the steel, reduces plasticity and the impelling strength of steel, makes welding property and the cold-bending property variation of steel.In view of the detrimentally affect of the steel of P, in order to guarantee drill pipe body good impelling strength is arranged, to carry out strict regulation and control to the P in the steel, make P≤0.013%, under the prerequisite that the process for making level can reach, make P≤0.010% as far as possible.

S is harmful elements to most steel grades, can cause steel " hot-short " property, reduces ductility and the impelling strength of steel, is forging and causing when rolling crackle.In addition, S also can significantly reduce welding property and the erosion resistance of steel, so in order to reduce the hazardness of S, guarantee that drill pipe body has good impelling strength and welding property, requires S≤0.005% in the steel, controls more low more well as far as possible.

As, Sn, Pb, Sb, Bi have bad influence to the performance of most of steel grades, therefore, often are called as " five-harmful elements " in the steel.When As content was higher, the fragility increase of steel, unit elongation, relative reduction in area and impelling strength reduced, and influence welding property.Sn can reduce the high-temperature mechanical property of steel and alloy greatly, and is also extremely harmful to the processing characteristics of steel.Pb can make the plasticity of steel slightly reduce, and makes the impact value of steel that bigger reduction be arranged.Sb increases intensity reduction, the fragility of steel.The easy segregation of Bi is in intergranular, alternate, thereby causes the fragility of steel, reduces plasticity and the hot strength of steel.Therefore, when composition designs, require As+Sn+Pb+Sb+Bi≤0.010%, have best intensity and impelling strength to guarantee drill pipe body.

The invention has the beneficial effects as follows: when satisfying the yield strength of standard-required, tensile strength and elongation index, improved the impelling strength of G level drill pipe body widely, thereby improved drilling rod safety in utilization, prolonged work-ing life of drilling rod.

Embodiment

Each example chemical ingredients is as shown in table 1.

Each example chemical ingredients of table 1 (mass percent/%)

Example	C	Si	Mn	P	S	Cr	Mo
								Example 1	0.26	0.30	1.10	0.012	0.003	0.94	0.30
Example 2	0.25	0.27	1.15	0.009	0.003	0.95	0.31
								Example 3	0.28	0.28	1.13	0.011	0.004	0.96	0.29
Example 4	0.29	0.28	1.09	0.011	0.004	0.97	0.27
								Example 5	0.27	0.25	1.12	0.010	0.003	0.96	0.28

Annotate: each example Al≤0.040% in the table; As+Sn+Pb+Sb+Bi≤0.010%; O≤0.002%; N≤0.006%; H≤0.0002%; All the other are Fe and the trace elements that can not remove, and mass percent amounts to 100%.

The mechanical property of each example steel pipe is as shown in table 2.

The non-metallic inclusion rank of each example steel pipe is as shown in table 3.

Example	Category-A (thin system)	Category-B (thin system)	C class (thin system)	D class (thin system)	The DS class
						Example 1	1	0.5	0.5	0.5	/
Example 2	1	0.5	0.5	0.5	/
						Example 3	1	0.5	0.5	0.5	/
Example 4	1	1	0.5	0.5	/
						Example 5	1	0.5	0.5	0.5	/

Claims

1. G grade high ductility drill pipe body weldless steel tube, it is characterized in that: the quality percentage chemical ingredients of weldless steel tube material is: C 0.20～0.30; Si 0.15～0.35; Mn 1.00～1.30; P≤0.013; S≤0.005; Cr 0.80～1.10; Mo 0.20～0.40; Al≤0.040; As+Sn+Pb+Sb+Bi≤0.010; O≤0.002; N≤0.006; H≤0.0002; All the other are Fe and the trace elements that can not remove, and mass percent amounts to 100%; The production method of this weldless steel tube is to adopt molten iron and steel scrap to do raw material, through hot metal pretreatment → top and bottom combined blown converter smelting → LF external refining → VD vacuum outgas → round billet continuous casting, obtain circular pipe blank, grow, weigh, spray mark → warehouse-in through a heating → perforation → tube rolling → tube reducing or sizing → cold bed cooling → sawing → aligning → flaw detection → hand inspection → survey again, to justify base and be rolled into weldless steel tube, and after the steel pipe total length carried out 880 ℃～920 ℃ quenchings and add the heat treatment quenching and tempering of 620 ℃～660 ℃ of tempering, make high tenacity drill pipe body weldless steel tube.