CN101724793A - Process for producing non-quenched and tempered N80 steel grade petroleum pipeline - Google Patents

Abstract

The invention relates to the technical field of metallurgy, in particular to a process for producing a non-quenched and tempered N80 steel grade petroleum pipeline. According to the technical scheme, the non-quenched and tempered N80 steel grade petroleum pipeline comprises the following components in percentage by mass: C: 0.34 to 0.38; Si: 0.25 to 0.40; Mn: 1.45 to 1.70; V: 0.11 to 0.16; P: not more than 0.025; S: not more than 0.025; Als: not more than 0.020; Cu: not more than 0.020, Ni: not more than 0.020; and Cr: not more than 0.25. The steel has good comprehensive mechanical property even at as rolled state, therefore, the on-line normalization or thermal refining process of the non-quenched and tempered N80 steel grade petroleum pipeline is canceled, the production process is simplified, the production efficiency is improved, and the production cost is reduced.

Description

Produce the technology of non-quenched and tempered N 80 steel grade petroleum pipeline

Technical field

The present invention relates to metallurgical technology field, be meant a kind of Technology that adopts alloying non-tempering steel and controlled rolling explained hereafter N80 steel grade petroleum pipeline especially.

Background technology

At present, both at home and abroad N80 steel grade petroleum pipeline production technique is mainly still for adopting modified thermal treatment after the thermal distortion, and this process energy consumption height, operation are many, cause the production cost height.

By research trial to " technology of non-quenched and tempered N 80 steel grade petroleum pipeline ", adopt the continuously cast bloom of no online normalizing-normalizing controlled rolling process and 36Mn2V steel grade, can produce the N80 steel grade petroleum pipeline that meets the API standard-required.

Summary of the invention

The purpose of this invention is to provide a kind of employing alloying non-tempering steel and temperature-controlled rolling explained hereafter N80 steel grade petroleum pipeline; because this steel grade just possesses good comprehensive mechanical properties in rolling state; thereby realize the online normalizing of petroleum pipeline or the modifier treatment technology of this grade of steel of cancellation; simplify its production technique; enhance productivity, reduce production costs.

According to technical scheme provided by the invention, the composition of described non-quenched and tempered N 80 steel grade petroleum pipeline is as follows: C0.34～0.38, Si0.25～0.40, Mn1.45～1.70, V0.11～0.16, P≤0.025, S≤0.025, Als≤0.020, Cu≤0.20, Ni≤0.20, Cr≤0.25; Unit is a mass percent.

The technology of producing described non-quenched and tempered N 80 petroleum pipeline comprises the steps:

A, heating: pipe is heated to 1250～1280 ℃ in ring furnace, and heat-up time is more than 3 hours, to guarantee that heating of pipe blank is even;

B, perforation: the heat pipe base after will heating is bored a hole on tapping machine, and the temperature of the hollow billet that the perforation back forms is controlled at more than 1200 ℃;

C, tandem rolling: the hollow billet after will boring a hole after winding arbor extraction press takes off pipe, transfers to the sizing unit through transport roller way through retained mandrel tandem rolling unit tandem rolling again; Transmission speed is controlled at 1.6～1.8m/s, and normal transmission speed has reduced by 20%～10%, and the suitable reduction of transmission speed helps controlling the hollow billet cooling and reaches grain growth, improves the purpose of intensity;

D, sizing: the hollow forging that forms behind tandem rolling forms steel pipe again through sizing mill group sizing; Finishing temperature during sizing is controlled at 800～850 ℃;

E, the cooling of cold bed blower fan: steel pipe uses blower fan to cool off fast after entering cold bed.

Adopt non-hardened and tempered steel following advantage to be arranged: (1) save energy than the well casing that produces oil with quenched and tempered steel; (2) reduce production process, improve the stability of fished pipe dimensional precision; (3) simplify production technique, shorten the production cycle, reduce cost; (4) improve working conditions, realize cleaner production.In addition, adopt the production of 36Mn2V steel grade to meet API standard N 80 petroleum pipelines than having the low cost advantage of cost of material with the production of 34Mn2VN steel grade.

Embodiment

Because N80 steel grade petroleum pipeline product is except that requiring to have the high strength, also need satisfy product in use to the technical requirements of plasticity, toughness etc.Therefore, the content proportioning of carbon and alloying element is scientific and reasonable in the steel, and makes every effort to harmful element, nonmetal inclusion and gas content in the steel are dropped to bottom line.

For this reason, have only the carbon content in the suitable reduction steel, could satisfy steel pipe in use to plasticity and flexible requirement, the present invention adopts the dual technology of alloy strengthening and process strengthening to reach high strength and makes it have certain plasticity and toughness.

In order to achieve the above object, the present invention adopts following technical scheme.

1) steel grade is selected

Initial the present invention adopts the steel grade of 33Mn2V to test, and test-results is unsatisfactory, and ballistic work can not satisfy the API specified requirement.

By analysis, decision adopts the steel grade of 36Mn2V to test, and test-results meets the requirement of API mark.Satisfy big condition of producing, adopt this technology can carry out large batch of production.Its chemical ingredients sees Table 1.

The chemical ingredients (wt%) of table 136Mn2V steel

??C	??Si	??Mn	??V	??P	??S	??Als	??Cu	??Ni	??Cr
										??0.34～0.38	??0.25～0.40	??1.45～1.70	??0.11～0.16	??≤0.025	??≤0.025	??≤0.020	??≤0.20	??≤0.20	??≤0.25

2) formulate operational path

Adopt heating-perforation-MPM tandem rolling-sizing-cold bed blower fan refrigerative operational path, production process controlled rolling speed, rolling temperature, thus reach the purpose that improves grade of steel.

Concrete technology is as follows:

1, heating: pipe is heated to 1250～1280 ℃ in ring furnace, and heat-up time is more than 3 hours, thereby the assurance heating of pipe blank is even.

2, perforation: the heat pipe base is bored a hole through tapping machine, and the temperature of the hollow billet that the perforation back forms is controlled at more than 1200 ℃.

3, MPM tandem rolling: hollow billet takes off pipe behind retained mandrel tandem rolling unit (MPM) tandem rolling, transfer to the sizing unit through transport roller way, transmission speed is controlled at 1.6～1.8m/s, normal transmission speed has reduced by 20%～10%, the suitable reduction of transmission speed helps controlling the hollow billet cooling and reaches grain growth, improves the purpose of intensity.

4, sizing: the hollow forging that forms behind tandem rolling is again through sizing unit sizing,, form steel pipe; Finishing temperature during sizing is controlled at 800～850 ℃.

5, cold bed blower fan cooling: steel pipe uses blower fan to cool off fast after entering cold bed.

Adopt this processing method to reduce normalizing-reheat operation, production line is shortened, save production cost, enhance productivity.Utilize this processing method to produce the non-quenched and tempered N 80 petroleum pipeline in enormous quantities, wherein heavy caliber petroleum pipe (Φ 339.7mm specification non-quenched and tempered N 80 sleeve pipe) is successfully produced, through checking the every performance requriements that all meets the API standard.

The present invention is by selecting suitable steel grade for use, the deformation system of strict each unit of control, speed system, the success of methods such as control finishing temperature and speed of cooling is rolling non-quenched and tempered N 80 steel grade petroleum pipeline.

The present invention has reduced traditional normalizing-reheat operation, and production line is shortened, and saves production cost, enhances productivity.The non-quenched and tempered N 80 petroleum pipeline performance that adopts this processing method to produce meets the API standard.

Be example with Φ 339.7 telescopic productions below:

Φ 339.7 * 13.06mm sleeve pipe of N80 grade of steel;

1. the pipe of Shi Yonging: Φ 330mm * 2.15m;

Material: 36Mn2V;

2. the hollow billet specification of boring a hole: Φ 376 * 18.75 * 8360mm;

3. mandrel mill-made shell specification: Φ 344.8mm * 13.4mm * 129200mm;

4. production tube specification behind the crop end: Φ 339.7mm * 13.06mm * 11800mm;

The thermal distortion instrument:

Top specification: Φ 328mm top;

Guide plate specification: 330mm guide plate;

Plug specification: Φ 326.5mm plug;

Push rod specification: Φ 300 push rods;

Finishing temperature: 810 ℃;

Finished product sleeve pipe mechanical property sees the following form:

Specification	Grade of steel	Grade of steel	Yield strength MPa	Tensile strength MPa	Elongation %	??Akv1	??Akv2	??Akv3	Size
										339.7*13.06 sleeve pipe	?N80-1	??36Mn2V	??565	??790	??26	??19	??16	??21	??7.5T

The english abbreviation of described retained mandrel continuous rolling-tube unit is MPM, i.e. the abbreviation of Multi-Stand Pipe Mill is the visual plant in the seamless steel tube production.The operation to plug in the whole operation of rolling of retained mandrel tandem rolling tube machine is controlled, and it is advanced with constant speed of setting, when the operation of rolling finishes, by winding arbor extraction press with hollow forging with after plug separates, hollow forging is shifted into next procedure and further processes; Plug then returns, and recycles after behind the dial-out rolling line, cooling off, lubricating.

Winding arbor extraction press is the integral part of retained mandrel continuous rolling-tube unit, and when the operation of rolling finished, winding arbor extraction press separated hollow forging with plug, and hollow forging is shifted into next procedure and further processes then.

The sizing unit is the milling train that in the hot finished steel pipe production hollow forging is carried out sizing processing.

Finishing temperature be in the sizing unit last frame roll the back temperature, the temperature after just all rolling process are finished.

Described cold bed is to make rolling back production tube be cooled to a kind of conventional machinery device of normal temperature in the seamless steel tube production.

The pipe of pipe after perforation is commonly referred to hollow billet, and the pipe of hollow billet behind tandem rolling is commonly referred to hollow forging.

Claims (2)

1. non-quenched and tempered N 80 steel grade petroleum pipeline is characterized in that, the composition of described petroleum pipeline is as follows: C0.34～0.38, Si0.25～0.40, Mn1.45～1.70, V0.11～0.16, P≤0.025, S≤0.025, Als≤0.020, Cu≤0.20, Ni≤0.20, Cr≤0.25; Unit is a mass percent.

2. the technology of the described non-quenched and tempered N 80 petroleum pipeline of production claim 1 is characterized in that, described technology comprises the steps:

A. heating: pipe is heated to 1250～1280 ℃ in ring furnace, and heat-up time is more than 3 hours, to guarantee that heating of pipe blank is even;

B, perforation: the heat pipe base after will heating is bored a hole on tapping machine, and the temperature of the hollow billet that the perforation back forms is controlled at more than 1200 ℃;

C, tandem rolling: the hollow billet after will boring a hole after winding arbor extraction press takes off pipe, transfers to the sizing unit through transport roller way through retained mandrel tandem rolling unit tandem rolling again; Transmission speed is controlled at 1.6～1.8m/s, and normal transmission speed has reduced by 20%～10%, and the suitable reduction of transmission speed helps controlling the hollow billet cooling and reaches grain growth, improves the purpose of intensity;

D, sizing: the hollow forging that forms behind tandem rolling forms steel pipe again through sizing mill group sizing; Finishing temperature during sizing is controlled at 800～850 ℃;

E, the cooling of cold bed blower fan: steel pipe uses blower fan to cool off fast after entering cold bed.