Lotus-Type Porous Nickel-Free Stainless Steel with High Temperature Nitriding
Lotus-type porous Fe-25wt.%Cr and Fe-23wt.%Cr-2wt.%Mo alloys were fabricated by continuous zone melting technique in pressurized hydrogen gas. After applying a high temperature nitriding treatment, the fabricated Lotus-type porous nickel-free stainless steel absorbed larger amount of nitrogen compared with non-porous alloy of the same composition since the surface area exposed to the gas is larger in the porous samples. In the Lotus-type porous Fe-25wt.%Cr and Fe-23wt.%Cr-2wt.%Mo alloys the nitrogen concentration after the nitriding achieved was approximately 1.2 wt.%. Only austenite peaks were detected in the profile of both Fe-Cr-N alloys after the nitriding treatment. Neither CrN nor Cr2N were identified by XRD in any specimen after the nitriding.
T. Chandra, K. Tsuzaki, M. Militzer and C. Ravindran
K. Alvarez et al., "Lotus-Type Porous Nickel-Free Stainless Steel with High Temperature Nitriding", Advanced Materials Research, Vols. 15-17, pp. 756-761, 2007