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Duplex stainless steel

一种双相不锈钢、管线管的技术，应用在铁素体·奥氏体双相不锈钢领域，能够解决耐腐蚀性变差、抗应力腐蚀裂纹性不够、焊接部易于发生脆化耐腐蚀性等问题，达到焊接性优良、抗应力腐蚀裂纹性优良的效果

Active Publication Date: 2016-06-22
NIPPON STEEL CORP
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  • Abstract
  • Description
  • Claims
  • Application Information

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Problems solved by technology

[0006] However, in the duplex stainless steel described in Patent Document 1, corrosion resistance tends to deteriorate at the welded portion during welding with a large heat input.
In addition, in the duplex stainless steel described in Patent Document 2, intermetallic compounds are precipitated at the welded portion during welding with a large heat input. Insufficient stress corrosion cracking resistance in chloride environments containing corrosive associated gases such as carbon dioxide and hydrogen sulfide when transporting oil and natural gas

Method used

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Examples

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Embodiment

[0082]Duplex stainless steels (inventive examples: test numbers 1 to 11, comparative examples: test numbers 12 to 25) having the chemical compositions shown in Table 1 below were melted in a vacuum melting furnace with a capacity of 150 kg, and cast into steel ingots. Next, each ingot was heated to 1250° C., and forged into a 40-mm-thick plate. Thereafter, each plate material was heated again to 1250° C., and rolled to 15 mm by hot rolling (working temperature 1050° C. or higher). Then, each sheet material after rolling was subjected to a solution heat treatment (treatment of soaking at 1070° C. for 30 minutes, followed by water cooling) to prepare a test steel sheet.

[0083] Table 1

[0084]

[0085] In order to evaluate the weldability of these test steel plates, first, a plate material having a thickness of 12 mm, a width of 100 mm, and a length of 200 mm, with a V-groove of 30 degrees on the long side was prepared by machining. figure 1 A plate 10 produced by mach...

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Abstract

The present invention provides a duplex stainless steel which is excellent in weldability during welding with high heat input and excellent in resistance to stress corrosion cracking in a chloride environment containing corrosive associated gas. The duplex stainless steel has a chemical composition containing, by mass %, C: 0.03% or less, Si: 0.2% to 1%, Mn: 5.0% or less, P: 0.040% or less, S: 0.010% or less, sol .Al: 0.040% or less, Ni: 4% to 8%, Cr: 20% to 28%, Mo: 0.5% to 2.0%, Cu: greater than 2.0% and less than or equal to 4.0%, N: 0.1% to 0.35%, The remainder is composed of Fe and impurities, and satisfies the relationship between the following formula (1) and formula (2). In addition, one or more of V, Ca, Mg, B, and rare earth elements may be contained instead of a part of Fe. 2.2Cr+7Mo+3Cu>66...(1); Cr+11Mo+10Ni<12(Cu+30N)...(2); among them, the symbols of each element in formula (1) and formula (2) Indicates the content of each element in steel (unit: mass %).

Description

technical field [0001] The present invention relates to a ferrite-austenite duplex stainless steel with excellent resistance to stress corrosion cracking, and more specifically, to a duplex stainless steel suitable for use as line pipe steel for transporting oil and natural gas. Background technique [0002] In oil and natural gas produced from oil fields and gas fields, carbon dioxide (CO 2 ), hydrogen sulfide (H 2 S) and other corrosive gases. In line pipes transporting such highly corrosive oil and natural gas, general corrosion (general corrosion), which causes stress corrosion cracking (Stress Corrosion Cracking: SCC), sulfide stress cracking (Sulfide Stress Cracking: SSC), and wall thickness reduction, has become a problem. In particular, stress corrosion cracking (SCC) and sulfide stress cracking (SSC) are more serious problems because of their fast growth rate, short time for cracks to penetrate the line pipe, and local occurrence. Therefore, the aforementioned st...

Claims

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Application Information

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Patent Type & Authority Patents(China)
IPC IPC(8): C22C38/00C22C38/58
CPCC22C38/001C22C38/02C22C38/42C22C38/44C22C38/58C22C1/02
Inventor 天谷尚高部秀树小川和博
Owner NIPPON STEEL CORP
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