CN105986178A

CN105986178A - Alloy structural steel

Info

Publication number: CN105986178A
Application number: CN201510048923.9A
Authority: CN
Inventors: 杨斌
Original assignee: Chongqing Canton Road Facilities Co Ltd
Current assignee: Chongqing Canton Road Facilities Co Ltd
Priority date: 2015-01-30
Filing date: 2015-01-30
Publication date: 2016-10-05

Abstract

The invention discloses an alloy structural steel. The alloy structural steel comprises the following chemical components by weight: 0.25 to 0.35% of C, 1.2 to 1.5% of Mn, 0.5 to 0.7% of Si, no more than 0.015% of P, no more than 0.01% of S, no more than 0.05% of Cr, no more than 0.1% of Ni, 0.05 to 0.2% of V, no more than 0.1% of Cu and no more than 0.01% of Al, with the balance being Fe and unavoidable impurities. The carbon equivalent Ce of the alloy structural steel is no more than 0.4%. The invention also provides a heat-insulation oil pipe manufactured from the alloy steel. Only normalization is need while thermal refining is not needed; processing technology is simple; and product quality is stable.

Description

A kind of structural alloy steel

Technical field

Present disclosure relates to a kind of structural alloy steel.

Background technology

Thermal recovery technology develops along with petroleum industry technology, and low pressure well, heavy oil wells, OW and low temperature area oil well are stabilized and increased one of daily output most effectual way by it.It is widely used and promotes.Especially heavy oil wells contains the paraffin of higher proportion and the crude oil of Colophonium, and feature is that ratio is great, and viscosity is high, the mink cell focus of poor fluidity.And some OWs, owing to the digging time is long, formation pressure is low, and crude oil fluidity is poor, and digging is the most difficult, in order to ensure that the daily output of oil well is stable or improves, it is necessary to popularization and application thermal recovery technology increases digging amount.Due to developing rapidly of thermal recovery technology, the high viscosity viscous crude being referred to as " underground deadlock dragon " in the past ground of jumping out is made to become highly important petrochemical material.

Along with being continuously increased of thickened oil recovery, thermal recovery technology is developed rapidly, and the demand of corresponding insulated tubing (the most heat insulation bimetallic tube) is greatly increased.

The principle of thermal recovery technology: mainly utilize special insulated tubing to inject high temperature and high pressure steam to underground heavy oil tested layer.Make it stop in oil reservoir 7～15 day time, thus reach to soften crude oil effect, improve crude oil temperature, reduction viscosity, increase mobility, make crude oil strengthen blowing ability or increase the technology of acquisition capacity by means of oil pumper.

Insulated tubing is made up of two-layer steel pipe.Outer tube is also known as trocar sheath, and inner tube is also known as internal lining pipe.Between ectonexine pipe, fill up adiabator (as the multilayer bindings such as refractory glass fibre, aluminium foil, silicate form), increase heat-insulating property by being evacuated between interlayer or injecting noble gas (He or Ar) simultaneously.

Working condition due to insulated tubing, it is necessary to use high intensity material pipe to be fabricated by.Especially internal layer bushing pipe bears High Temperature High Pressure (temperature T >=380 DEG C, pressure P >=36MPa), therefore, intensity must be used to reach N80 level, outer layer sleeve is under room temperature and works, and typically can apply intensity J55 level, it is possible to use and internal lining pipe equality strength steel.

Keeping certain interval between trocar sheath and the internal lining pipe of insulated tubing, internal lining pipe two ends must carry out thickening the most expanding processing during fabrication, and internal lining pipe must have good process industrial art performance.The connection application welding method of inner and outer pipes, inner and outer pipes need to have good welding performance (carbon equivalent Ce being generally available material controls).

Insulated tubing working condition is the most severe.Outer layer sleeve bearing temperature and pressure are equal to working site.But internal layer bushing pipe is in addition to bearing conveying high temperature and high pressure steam, due to inner and outer pipes temperature and pressure difference great disparity, produce stress especially severe, make whole body be under complex stress effect, often make whole body produce the defects such as bending, torsion or weld seam cracks, cracking and occur.The most inside and outside pipe end junction produces heat affected area due to welding, forces the plasticity of this part material to reduce, even if taking annealing or temper, is also extremely difficult to normal condition.Easily become the district of hiding of the defect such as crackle, cracking.

According to insulated tubing application characteristic and the manufacturing, body material typically selects high-quality low-alloy structural steel.Make body (flush end) by hot seamless tube method, improve the intensity of steel with modifier treatment.Especially internal lining pipe intensity must reach N80 level requirement.The inner and outer pipes of Japan and the U.S. is application 25Mn2 steel pipe.Its internal lining pipe should use water as quenching medium quenching, more tempered process forms (metallographic structure is tempered sorbite).Germany and some producer of China then select 25CrMo steel pipe,

Make quenching medium quenching with oil, add temper and form.The common ground of both hardening and tempering methods: technological equipment is complicated, investment is big, technical merit is high, operation easier is big, qualification rate is low, cost is high, forces finished product expensive.

Summary of the invention

It is an object of the invention to provide a kind of structural alloy steel, utilize trocar sheath and the internal lining pipe of this alloy structure steel making insulated tubing, processing technique is simple, improves trocar sheath and the welding performance of internal lining pipe of insulated tubing.The purpose of the present invention is achieved through the following technical solutions:

A kind of structural alloy steel, the chemical analysis of this steel is measured by the percentage by weight, C:0.25%-0.35%, Mn: 1.2%-1.5%, Si: 0.5%-0.7%, P :≤0.015%, S :≤0.01%, Cr :≤0.05%, Ni :≤0.1%, V:0.05%-0.2%, Cu :≤0.1%, Al :≤0.01%, surplus is Fe and is inevitably mingled with；Carbon equivalent Ce≤0.4%.

A kind of processing technique utilizing above-mentioned structural alloy steel to produce insulated tubing, described processing technique step is:

(1) to through checking qualified pipe to carry out blanking；(2) heating pipe, heating-up temperature is 1300-1340 DEG C；(3) bore a hole under heat is felt relieved；(4) take the lead process；(5) annealing；(6) pickling is carried out；(7) phosphatization saponification is carried out；(8) cold-drawn process is carried out；(9) again anneal the materials in the tube after cold-drawn, pickling, phosphatization saponification and cold-drawn process, until steel pipe sizes meets design requirement；(10) materials in the tube being carried out normalizing heat treatment, normalizing temperature is 950-1000 DEG C；(11) materials in the tube are aligned and crop end；(12) carrying out physical and chemical inspection and Non-Destructive Testing, the metallographic structure of steel pipe should be ferrite and pearlite, must not be with the presence of Widmannstatten structure.

Utilizing structural alloy steel of the present invention to produce insulated tubing, without modifier treatment in processing technique, and only need normalizing heat treatment, technological equipment is simple, easy and simple to handle, stable performance, and qualification rate is high；Internal lining pipe and trocar sheath use material of the same race, same process, obtain identical mechanical performance, processing performance and metallographic structure, internal lining pipe two ends are thickeied and create favorable conditions with expanding, inner and outer pipes welding by this, welding performance is good, weld heat-affected zone stress sensitivity is inconspicuous, it is possible to increase the service life of insulated tubing.

Detailed description of the invention

Below in conjunction with embodiment, the invention will be further described:

The chemical analysis of structural alloy steel of the present invention is measured by the percentage by weight, C:0.25%-0.35%, Mn: 1.2%-1.5%, Si: 0.5%-0.7%, P :≤0.015%, S :≤0.01%, Cr :≤0.05%, Ni :≤0.1%, V:0.05%-0.2%, Cu :≤0.1%, Al :≤0.01%, surplus is Fe and is inevitably mingled with；Carbon equivalent Ce≤0.4%.The smelting process of structural alloy steel: electric furnace (EF+LF+VD) adds the smelting of external refining method and forms.

In the macrostructure test piece of steel must not with the presence of macroscopic white point, Residual hole, layering, crackle, bubble, be mingled with, the defect such as skull patch.The macrostructure allowed；General Loosen, center porosity and segregation etc. are respectively not more than 1.5 grades.

The non-metallic inclusion of steel is specified by GB10561, and qualified rank is pressed ISO judge picture and graded:

Structural alloy steel produces the processing technique step of insulated tubing:

Claims

1. a structural alloy steel, it is characterised in that: the chemical analysis of this steel is measured by the percentage by weight, C:0.25%-0.35%, Mn: 1.2%-1.5%, Si: 0.5%-0.7%, P :≤0.015%, S :≤0.01%, Cr :≤0.05%, Ni :≤0.1%, V:0.05%-0.2%, Cu :≤0.1%, Al :≤0.01%, surplus is Fe and is inevitably mingled with；Carbon equivalent Ce≤0.4%.