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Martensitic stainless steel

A stainless steel, system technology, applied in the furnace type, furnace, heat treatment furnace, etc., can solve the problem of reduced SSC resistance

Inactive Publication Date: 2009-08-12
NIPPON STEEL CORP
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

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Problems solved by technology

For the same steel material, the SSC resistance will decrease if the hardness unevenness is large

Method used

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  • Martensitic stainless steel
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Examples

Experimental program
Comparison scheme
Effect test

Embodiment

[0082] Seamless steel pipes having various chemical compositions were produced, and the TS-YS and hardness unevenness of the produced seamless steel pipes were investigated.

[0083] investigation method

[0084] Steels having the chemical compositions shown in Table 1 were melted for each test number in Table 1 to produce billets. Each produced billet is subjected to hot forging and hot rolling to produce a seamless steel pipe.

[0085] Table 1

[0086]

[0087] Next, quenching and tempering were performed so that the 0.6% total tensile yield strength of each produced seamless steel pipe fell within the range of 758 to 862 MPa. Specifically, the quenching temperature was adjusted to 910°C, and the tempering temperature was adjusted within the range of 560°C to 630°C.

[0088] After quenching and tempering, the 0.6% total tensile yield strength (YS) and tensile strength (TS) of each seamless steel pipe were measured. A round bar test piece having a parallel portion ...

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Abstract

A martensitic stainless steel which contains, in terms of mass%, 0.010-0.030% C, 0.30-0.60% Mn, up to 0.040% P, up to 0.0100% S, 10.00-15.00% Cr, 2.50-8.00% Ni, 1.00-5.00% Mo, 0.050-0.250% Ti, up to 0.25% V, and up to 0.07% N, and contains at least either of up to 0.50% Si and up to 0.10% Al, the remainder being iron and incidental impurities. The martensitic stainless steel satisfies the relationship (1) and has a yield strength of 758-862 MPa. Due to this constitution, this martensitic stainless steel has a strength of the 110-ksi class (yield strength of 758-862 MPa), and the value obtained by subtracting the yield strength from the tensile strength is 20.7 MPa or more. 6.0<=Ti / C<=10.1 (1).

Description

technical field [0001] The invention relates to a martensitic stainless steel, in particular to a martensitic stainless steel used in a corrosive environment containing corrosive substances such as hydrogen sulfide, carbon dioxide, and chloride ions. Background technique [0002] In recent years, the deep wells of oil and gas fields have developed rapidly. Since these oil wells and gas wells (hereinafter, these are collectively referred to as oil wells) are relatively deep, steel materials used as oil well pipes in these oil wells are required to have a high yield strength. Recently, steel materials having a yield strength of 110 ksi class (0.6% total tensile yield strength of 758 MPa to 862 MPa) are used as oil pipes. [0003] In addition, oil wells contain hydrogen sulfide, carbon dioxide, and chloride ions. Therefore, steel materials for oil well pipes are required to have excellent SSC (Sulfide stress corrosion cracking: sulfide stress corrosion cracking) resistance an...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): C22C38/00C22C38/50
CPCC22C38/50C22C38/44C22C38/04C22C38/001C22C38/02C22C38/06C22C38/42C22C38/46C21D6/004C21D9/14C21D1/25
Inventor 高部秀树森友希植田昌克
Owner NIPPON STEEL CORP