Carburization of 316L austenitic stainless steel under para-equilibrium conditions resulted in extremely hard (about 1100HV) single-phase cases containing surface C concentrations of about 15mol% and very high residual compressive stresses (greater than 2GPa). Carburization produced an anelastic relaxation peak at 543K (1.0Hz), due to a C-containing defect with a highly anisotropic strain field. Interstitial solid-solution strengthening theories could explain the approximate three-fold increase in hardness, using reasonable parameters for the strain ellipsoids of these defects.

Interstitial Defects in 316L Austenitic Stainless Steel Containing “Colossal” Carbon Concentrations - an Internal Friction Study. A.H.Heuer, F.Ernst, H.Kahn, A.Avishai, G.M.Michal, D.J.Pitchure, R.E.Ricker: Scripta Materialia, 2007, 56[12], 1067-70