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High-strength thick-walled electric resistance welded steel pipe having excellent low-temperature toughness and manufacturing method thereof

A technology for electric resistance welded steel pipes and manufacturing methods, which is applied in the direction of electric resistance welding equipment, rigid pipes, manufacturing tools, etc., and can solve the problems of low reliability, unstrict requirements, and small degree of improvement in toughness, etc.

Active Publication Date: 2016-11-02
JFE STEEL CORP
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

However, due to the low toughness of resistance welded joints, there is a problem that reliability is low, and its use is limited to parts where low-temperature toughness and hydrogen induced cracking resistance (Hydrogen Induced Cracking, hereinafter also referred to as HIC) are not strictly required.
However, there is a problem that the steel plate used in the technique described in Patent Document 1 has a thickness of about 8.0 mm, which is thin, and the toughness of the welded part of the obtained electric resistance welded steel pipe is at the highest in terms of brittle transition temperature (fracture appearance transition temperature). About -40°C, the degree of toughness improvement is small

Method used

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  • High-strength thick-walled electric resistance welded steel pipe having excellent low-temperature toughness and manufacturing method thereof
  • High-strength thick-walled electric resistance welded steel pipe having excellent low-temperature toughness and manufacturing method thereof
  • High-strength thick-walled electric resistance welded steel pipe having excellent low-temperature toughness and manufacturing method thereof

Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0154] A billet (steel raw material) (wall thickness: 250 mm) having the composition shown in Table 1 was subjected to a hot rolling process consisting of heating under the conditions shown in Table 2, finish rolling, cooling after finishing rolling, and coiling, and the table was prepared. 2 hot-rolled steel strips with the plate thickness indicated. These hot-rolled steel strips are cut into predetermined widths, and then continuously subjected to roll forming, which is a common pipe-making process, by cold working to form a tubular molded body with a substantially circular cross-section. Then, the ends in the circumferential direction are butted against each other, the ends in the circumferential direction are heated to a melting point or higher by high-frequency resistance heating, pressure-bonded with a squeeze roll, and resistance welded, thereby performing a pipe-making process to produce an electric resistance welded steel pipe ( Outer Diameter: 26in.φ(660.4mmφ)). In ...

Embodiment 2

[0173] Using steel raw materials (billets) of steel Nos. A to F shown in Table 1, hot-rolled steel strips having thicknesses shown in Table 4 were produced through the hot rolling process under the conditions shown in Table 4. These hot-rolled steel strips were cut into predetermined widths, and the pipe-making processes of roll forming and electric resistance welding were continuously performed to produce electric resistance welded steel pipes with dimensions shown in Table 4. In addition, some steel pipes were provided with tapered grooves having the dimensions shown in Table 4 at the ends in the width direction of the steel pipes during roll forming. In addition, except for some steel pipes, resistance welding is performed in the air. For some steel pipes, a non-oxidizing gas is blown into the atmosphere during resistance welding. At this time, nozzles for gas injection were arranged in three stages, and the oxygen partial pressure was lowered to 45 mass ppm.

[0174] Nex...

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Abstract

An object of the present invention is to provide a high-strength thick-walled electric resistance welded steel pipe which has a yield strength of 400 MPa or more and is excellent in both low-temperature toughness and HIC resistance. After heating the raw steel material to a temperature range of 1200-1280°C and maintaining it, hot rolling is carried out so that the rolling rate in the non-recrystallization temperature range is 20% or more. The cooling speed is cooled to the cooling stop temperature below 630°C, coiled at a temperature above 400°C and below 600°C to make a hot-rolled steel strip, and the hot-rolled steel strip is subjected to roll forming and resistance welding. The electric resistance welded steel pipe is made, and the following heat treatment is further carried out: heating the resistance welded part so that the entire thickness of the wall thickness is in the range of 800°C to 1150°C, and then cooling to 630°C at an average cooling rate of 7 to 49°C / sec Hereinafter, the raw steel material contains C: 0.025 to 0.084%, Si: 0.10 to 0.30%, and Mn: 0.70 to 1.80% by mass %, and the content of P, S, Al, N, and O is adjusted, and further contains Nb: 0.001 to 0.065%, V: 0.001 to 0.065%, Ti: 0.001 to 0.033%, Ca: 0.0001 to 0.0035%, and Pcm satisfies 0.20 or less. Thus, a high-strength thick-walled electric resistance welded steel pipe excellent in both toughness and HIC resistance of the base metal portion and the electric resistance welded portion is produced.

Description

technical field [0001] The present invention relates to a high-strength thick-walled electric resistance welded steel pipe (high-strength thick-walled electric resistance welded steel pipe), and particularly relates to improvement of reliability of an electric resistance welded portion. In addition, the "high strength" mentioned here means the case where the yield strength YS is 400 MPa or more, and the "thick wall" means the case where the wall thickness is 16-32 mm. Background technique [0002] Conventionally, electric resistance welded steel pipes have been used for mining, transportation, and the like of oil and natural gas. However, due to the low toughness of resistance welded joints, there is a problem that reliability is low, and its use is limited to parts where low-temperature toughness and hydrogen induced cracking resistance (Hydrogen Induced Cracking, hereinafter also referred to as HIC) are not strictly required. . [0003] In order to solve this problem, fo...

Claims

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Application Information

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Patent Type & Authority Patents(China)
IPC IPC(8): C22C38/00B21B3/00B21C37/08C21D1/00C21D8/02C21D9/08C21D9/50C22C38/14C22C38/58
CPCB21C37/08B21B3/00C21D8/02C21D9/08C21D9/50C21D1/00C22C38/14C22C38/001C22C38/002C22C38/02C22C38/04C22C38/06C22C38/08C22C38/12C22C38/16C21D8/0226C21D8/0263C21D9/085C21D2211/005C21D8/105C21D8/00C22C38/00Y10T428/12958Y10T428/12979Y10T428/12972Y10T428/12965Y10T428/13B21B27/06B23K11/0073B23K11/0873C22C38/58B32B1/08F16L9/02F16L9/17B21B27/08
Inventor 丰田俊介后藤聪太冈部能知井上智弘江木基明米本笃志
Owner JFE STEEL CORP
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