Nippon Steel Sumitomo Metal Corporation

Nippon Steel Corporation

Akiko Tomio

Masayuki Sagara

Yusaku Tomio

Masaki Ueyama

A Cr&#x2014;Ni alloy having high yield strength and high resistance to sulfuric acid general corrosion at a high temperature of 250&#xb0; C. is provided. The Cr&#x2014;Ni alloy has a chemical composition consisting of, in mass %, Si: 0.01 to 0.50%, Mn: 0.01 to 1.00%, Cr: 21.0 to 27.0%, Ni: 40.0 to less than 50.0%, Mo: 4.5 to less than 9.0%, W: 2.0 to 6.0%, Cu: more than 2.0% and not more than 6.0%, Co: 0.01 to 2.00%, one or two kinds selected from the group consisting of Ca and Mg: 0.001 to 0.010% in total, sol. Al: 0.005 to 0.200%, N: 0.01 to 0.20%, and the balance being Fe and impurities. The dislocation density in the Cr&#x2014;Ni alloy satisfies the following Formula (1):8.00&#xd7;10&#x2264;&#x3c1;&#x2264;2.50&#xd7;10+1.40&#xd7;10&#xd7;[Cu+Co]&#x2003;&#x2003;(1)

Cr-Ni alloy and seamless steel pipe made of Cr-Ni alloy

The high alloy for oil well according to the present embodiment consists of, in mass %, C: 0.03% or less, Si: 1.0% or less, Mn: 0.05 to 1.5%, P: 0.03% or less, S: 0.03% or less, Ni: 26.0 to 40.0%, Cr: 22.0 to 30.0%, Mo: 0.01% or more to less than 5.0%, Cu: 0.1 to 3.0%, Al: 0.001 to 0.30%, N: more than 0.05% to 0.30% or less, O: 0.010% or less, and Ag: 0.005 to 1.0%, wherein the alloy satisfies the following Formula (1) and (2), wherein the high alloy for oil well has yield strength of 758 MPa or more:5&#xd7;Cu+(1000&#xd7;Ag)&#x2265;40&#x2003;&#x2003;(1)Cu+6&#xd7;Ag&#x2212;500&#xd7;(Ca+Mg+REM)&#x2264;3.5&#x2003;&#x2003;(2)

High alloy for oil well

A stainless steel contains, by mass %, C: 0.005% to 0.03%, Si: 0.05% to 1.0%, Mn: 0.1% to 4.0%, Ni: 3% to 8%, Cr: 20% to 35%, Mo: 0.01% to 4.0%, Al: 0.001% to 0.30%, N: 0.05% to 0.60%, one or more selected from Re: 2.0% or less, Ga: 2.0% or less, and Ge: 2.0% or less, and a balance consisting of Fe and impurities.

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Tokyo, Japan

Akiko Tomio