Abstract: Surface hardened ferritic or austenitic stainless steel articles, especially automobile exhaust flanges and Hego bosses, are produced as sintered powder metal parts having a relatively soft ferritic core and a hardened outer surface layer. The method of manufacturing such parts includes compacting a stainless steel powder, followed by sintering, repressing, and surface hardening in an atmosphere containing nitrogen so that the final part density is at least 88% of theoretical density. Such parts have improved strength and are useful as automotive exhaust flanges and Hego bosses.