High interstitial austenitic stainless steels (HIS) contain approximately 18% chromium, 18% manganese
and a combined carbon plus nitrogen content between 0.8 and 1.1%. They are non-magnetic and show
outstanding mechanical properties and good corrosion resistance. This paper presents test results of
two newly developed non-magnetic high interstitial austenitic stainless steels with PREN of 28 and 36.
Two variants were produced:
a Fe18Cr18Mn0.85CN-HIS with 0.85% (C+N) CN0.85
A Fe18Cr18Mn1.1CN2.2Mo-HIS with 1.1% (C+N) and 2.2% Mo CN1.1Mo
Mechanical and corrosion properties were investigated in solution annealed condition. After solution
annealing, both alloys possess fully austenitic microstructure without detrimental phases. They exhibit
similar yield strength (> 600 MPa), elongation (> 60 %) and impact energy (> 350 J), while ultimate
tensile strength is higher for FeCrMn1.1CN2.2Mo-HIS (> 980 MPa) than for FeCrMn0.85CN-HIS (> 930
MPa). FeCrMn1.1CN2.2Mo-HIS shows better pitting corrosion resistance and higher critical pitting
temperature than FeCrMn0.85CN-HIS as well as higher pitting potential in 3.56 % NaCl at RT. The Morich
variant did not display cracking or pitting after stress corrosion cracking test. The new nonmagnetic
high interstitial austenitic stainless steels are promising grades for application in oil and gas
industry due to their outstanding combination of high strength, good ductility and excellent corrosion
properties.