Patent ID: 10597760

Abstract:
There is provided a high-strength steel material for oil well having a chemical composition consisting, by mass percent, of C: 0.60-1.4%, Si: 0.05-1.00%, Mn: 12-25%, Al: 0.003-0.06%, P: ≤0.03%, S: ≤0.03%, N: <0.1%, Cr: ≥0% and <5.0%, Mo: ≥0% and <3.0%, Cu: ≤0% and <1.0%, Ni: ≥0% and <1.0%, V: 0-0.5%, Nb: 0-0.5%, Ta: 0-0.5%, Ti: 0-0.5%, Zr: 0-0.5%, Ca: ≥0% and <0.005%, Mg: ≥0% and <0.005%, B: 0-0.015%, the balance: Fe and impurities, wherein Nieq [=Ni+30C+0.5Mn] is 27.5 or higher, a metal micro-structure is a structure consisting mainly of an FCC structure, a total volume fraction of ferrite and α′ martensite is less than 0.10%, and a yield strength is 862 MPa or higher.