Abstract: A Cr—Ni alloy having high yield strength and high resistance to sulfuric acid general corrosion at a high temperature of 250° C. is provided. The Cr—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—Ni alloy satisfies the following Formula (1): 8.00×1014???2.50×1015+1.

Abstract: A Cr—Ni alloy having high yield strength and high resistance to sulfuric acid general corrosion at a high temperature of 250° C. is provided. The Cr—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—Ni alloy satisfies the following Formula (1): 8.00×1014???2.50×1015+1.

Abstract: 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×Cu+(1000×Ag)2?40??(1) Cu+6×Ag?500×(Ca+Mg+REM)?3.5??(2) where, each element symbol in each Formula is substituted by the content (in mass %) of each element.

Abstract: 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.

Abstract: 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 Formulae (1) and (2), wherein the high alloy for oil well has yield strength of 758 MPa or more: 5×Cu+(1000×Ag)2?40 ??(1) Cu+6×Ag?500×(Ca+Mg+REM)?3.5 ??(2) where, each element symbol in each Formula is substituted by the content (in mass %) of each element.

Abstract: 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%, 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.