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Martensitic stainless steel

一种马氏体不锈钢、化学组成的技术，应用在马氏体不锈钢领域，达到耐腐蚀性优良、韧性优良的效果

Inactive Publication Date: 2006-08-09
NIPPON STEEL CORP
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

Even if the addition amount of Mo is increased, if Mo precipitates as an intermetallic compound, no improvement in corrosion resistance can be expected

Method used

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Examples

Experimental program
Comparison scheme
Effect test

Embodiment

[0085] Steel having the chemical composition shown in Table 1 (the amount of Mo is the added amount) was melted and cast into ingot iron. These ingots were heated at 1250° C. for 2 hours, and then forged into ingots. These iron ingots were again heated at 1250° C. for 2 hours to obtain a rolled material having a thickness of 10 mm. After cooling down to room temperature, the calendered material was heated at 950° C. for 15 minutes, and then cooled with water. A part of them was left to stand after being cooled with water, and the remaining part was heat-treated by aging treatment at 100° C. to 620° C. for 1 hour after cooling with water.

[0086] In Table 1, steels A to U are steels with a high Mo content, steel V is a conventional super 13Cr steel, and steel W is a two-phase stainless steel. Among steels A to U with high Mo content, steels T and U do not satisfy the requirements of the present invention because the value of Ni-bal. is less than -4.5. The 2-phase stainless ...

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PUM

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Abstract

A martensitic stainless steel which has a essential chemical composition, in mass %, wherein C: 0.001 to 0.1 %, Si: 0.05 to 1.0 %, Mn: 0.05 to 2.0 %, P: 0.025 % or less, S: 0.010 % or less, Cr: 11 to 18 %, Ni: 1.5 to 10 %, sol.Al: 0.001 to 0.1 %, N: 0.1 % or less, O: 0.01 % or less, Cu: 0 to 5 %, and Mo forming a solid 3.5 to 7 %, wherein the following formula (1) is satisfied and optionally one or more elements selected from at least one group of the following A to C groups are further contained, and wherein the balance is composed of Fe, Mo forming no solid solution, if any, and impurities, formula (1): Ni-bal.= 30(C+N)+0.5(Mn+Cu)+Ni+8.2 -1.1(Cr+Mo+1.5Si) >= -4.5; A group - W: 0.2 to 5 %, B group - V: 0.001 to 0.50 %, Nb: 0.001 to 0.50 %, Ti: 0.001 to 0.50 % and Zr: 0.001 to 0.50 %, C group - Ca: 0.0005 to 0.05 %, Mg: 0.0005 to 0.05 %, REM: 0.0005 to 0.05 % and B: 0.0001 to 0.01 %. The martensitic stainless steel has the resistance to sulfide stress corrosion cracking being superior to that of super 13 Cr steel and exhibits the strength and corrosion resistance comparable to those of duplex stainless steel.

Description

technical field [0001] The present invention relates to a martensitic stainless steel excellent in carbon dioxide gas corrosion resistance and sulfide stress corrosion cracking resistance. The martensitic stainless steel described in the present invention can be used as an oil well pipe (OCTG) (oil country tubular goods) for drawing crude oil or natural gas containing carbon dioxide gas or hydrogen sulfide gas, or as a flow pipe or pipeline pipe for transporting these crude oils Materials for steel pipes (linepipe), oil well bottom machines, valves, etc. Background technique [0002] In recent years, as the environment of oil wells for extracting oil or natural gas has become increasingly harsh, corrosion of oil well pipes that are excavated from the ground and output crude oil, or piping used to directly transport crude oil without anti-corrosion treatment has become a major problem . [0003] In the past, oil wells exploiting crude oil with high carbon dioxide gas conten...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): C22C38/00C22C38/58
CPCC22C38/42C22C38/02C22C38/04C22C38/44
Inventor 近藤邦夫天谷尚
Owner NIPPON STEEL CORP
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