(19)
(11) EP 0 183 536 A3

(12) EUROPEAN PATENT APPLICATION

(88) Date of publication A3:
13.05.1987 Bulletin 1987/20

(43) Date of publication A2:
04.06.1986 Bulletin 1986/23

(21) Application number: 85308615

(22) Date of filing: 27.11.1985
(84) Designated Contracting States:
AT DE FR GB

(30) Priority: 30.11.1984 JP 25190884

(71) Applicant: NIPPON STEEL CORPORATION
 ()

(72) Inventors:
  • Nakazawa, Takanori Dainigijutsukenkyusho
     ()
  • Suzuki, Toru Dainigijutsukenkyusho
     ()
  • Sakamoto, Tetsu Dainigijutsukenkyusho
     ()
  • Yamauchi, Isamu
     ()

   


(54) Non-magnetic steel having high corrosion resistance and high strength for use as material of drill collar, and drill collar made of the steel


(57) A non-magnetic steel alloy having high corrosion resistance and high strength suitable for use as the material of a drill collar which operates under corrosive conditions, particularly under the conditions which cause stress corrosion cracking, and a drill collar made of the steel alloy. The steel alloy has a composition which essentially consists of: not greater than 0.02% of C, not greater than 2.0% of Si, not greater than 2.0% of Mn, 25 to 40% of Ni, 18 to 30% of Cr, 0.1 to 1.5% of A1, 1.5 to 3.0% of Ti, 0.0005 to 0.020% of Ca, not greater than 0.020% of N and the balance Fe and incidental impurities, and a drill collar made of the steel.






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