This group of stainless steels includes grades with higher Cr contents than those found in martensitic stainless steels. The higher Cr contents stabilize ferrite in the microstructure giving the group different mechanical properties. Ni and Mo additions are also made to improve mechanical properties but in substantially lower levels than those found in austenitic stainless steels. The strength and ductility levels of this group are moderate for steels but they do exhibit lower impact properties than most grades of steels.
These alloys are usually supplied in an annealed heat treatment condition. Melting does not require unusual attention. Castability of these alloys is moderate with fluidity problems.
Applications for this alloy group include corrosion resistant applications where the lower Cr grades are not sufficient and the higher cost austenitic grades are not necessary. Special applications of this group also utilize the magnetic nature of the alloys. Magnetic separators in chemical streams are a good example.