N80-grade electric resistance welding steel for oil casings and method for manufacturing N80-grade electric resistance welding steel

A technology of oil casing and manufacturing method, applied in the direction of temperature control, etc., can solve the problems of complex process, high carbon content and high alloy cost, and achieve the effects of simple heat treatment process, good impact toughness and alloy cost saving.

Active Publication Date: 2013-02-06
ANGANG STEEL CO LTD
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  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

The content of C in this paper is low, in order to improve the strength, it is necessary to add precious alloying elements Mo, Ni, and the cost of the alloy is high
[0014] In the published patents and documents, the C content is high, and the weldability of the steel strip is average; some add precious alloying elements Mo, Ni, Cu, etc., and the alloy cost is high; some require heat treatment of the whole tube
[0015] The steel for straight seam welded oil casing disclosed above meets the requirements of N80 steel pipe specified by the American Petroleum Institute API Spec 5CT, but the carbon content is relatively high, and the weldability and toughness are average; the alloy elements Mo, Ni, Cu are added, and the alloy cost is high; Tube heat treatment, complex process

Method used

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  • N80-grade electric resistance welding steel for oil casings and method for manufacturing N80-grade electric resistance welding steel
  • N80-grade electric resistance welding steel for oil casings and method for manufacturing N80-grade electric resistance welding steel

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Embodiment Construction

[0034] The present invention will be further explained below in combination:

[0035] The chemical composition of the test steel is shown in Table 1, the heating and rolling cooling process is shown in Table 2, and the mechanical properties are shown in Table 3.

[0036] Table 1 Chemical composition (wt, %)

[0037] Example

C

Si

Mn

P

S

Nb

Cr

Ti

Als

N

Fe

1

0.09

0.28

1.70

0.013

0.008

0.07

0.29

0.024

0.023

0.004

Margin

2

0.06

0.15

1.90

0.015

0.004

0.07

0.30

0.011

0.036

0.003

Margin

3

0.08

0.25

1.80

0.014

0.005

0.06

0.22

0.014

0.043

0.004

Margin

4

0.07

0.32

1.87

0.016

0.003

0.05

0.28

0.033

0.051

0.005

Margin

5

0.09

0.27

1.93

0.011

0.005

0.08

0.24

0.028

0.029

0.006

Margin

6

0.08

0.20

1.79

0.015

0.004

0.06

0.27

0.041

0.036

0.005

Margin

[0038] Table 2 Heating and rolling process

[0039]

[0040] Table 3 Mechanical properties of hot rolled state

[0041]

[0042] It can be seen from Table 3 that the high-strength and high-toughness ERW petroleum casing produced by the ...

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Abstract

The invention discloses N80-grade electric resistance welding steel for oil casings and a method for manufacturing the N80-grade electric resistance welding steel. The N80-grade electric resistance welding steel is characterized by comprising, by weight, from 0.05% to 0.09% of C, from 0.15% to 0.35% of Si, from 1.70% to 1.95% of Mn, lower than or equal to 0.020% of P, lower than or equal to 0.008% of S, from 0.010% to 0.050% of Ti, from 0.02% to 0.06% of Als, from 0.05% to 0.08% of Nb, from 0.20% to 0.30% of Cr, lower than or equal to 0.008% of N, the balance Fe and inevitable elements. The N80-grade electric resistance welding steel is excellent in weldability and good in impact toughness [under conditions that the temperature is 0 DEG C, the Akv is higher than 200J, and the SA (shear area) is larger than 90%]. Besides, after a steel strip made of the N80-grade electric resistance welding steel is made into a casing, only weld joints and heat affected zones need to be subjected to heat treatment, heat treatment for the integral casing is omitted, accordingly, a heat treatment process is simple, and the steel casing is low in production cost.

Description

Technical field [0001] The invention relates to a steel for straight seam resistance welded pipe (ERW / HFW) and a manufacturing method thereof, in particular to a high-strength N80 steel grade 1 ERW oil casing pipe with excellent weldability and impact toughness in API SPEC 5CT Steel and its manufacturing method. Background technique [0002] Petroleum casing is one of the most commonly used special oil pipes in oil fields. It is used in large quantities and costs a lot. It is an indispensable construction material in oil and gas field drilling operations. Compared with seamless pipes, HFW casing has significant advantages such as uniform wall thickness, high dimensional accuracy, good perforation performance, strong collapse resistance, and low cost. It is gradually replacing traditional seamless steel pipes. [0003] The API Spec 5CT standard stipulates that seamless pipes and longitudinally welded pipes can be used to manufacture petroleum casing. As far as the longitudinal sea...

Claims

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Application Information

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IPC IPC(8): C22C38/38B21B37/74
Inventor 黄明浩黄国建徐烽孔祥磊张英慧
Owner ANGANG STEEL CO LTD
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