EVO SP's Custom Shop Special is finished in KimPro charcoal gray on the frame and black
Ferritic Nitro Carburizing (FNC) on the slide.
Ferritic nitrocarburizing (sometimes abbreviated FNC) is a case hardening processes that diffuses nitrogen and carbon into ferrous metals at sub-critical temperatures during a salt bath.
Founded in 1946, the company pioneered advancements in
ferritic nitrocarburizing with the development of the H&M Blacknitride+[TM] process.
Atmosphere Annealing has more than 400,000 tons of installed heat treating capacity including annealing,
ferritic nitrocarburizing, normalising, and quench and temper processing for various industries, including automotive, light and heavy truck, agriculture, and energy.
I'm betting that these cases are made from a
ferritic stainless steel, which doesn't contain nickel at all.
General corrosion is attributed to the preferential dissolution of the
ferritic phase and it often manifests by a cementite scale ([Fe.sub.3]C) formation.
* Solution strengthened
ferritic ductile iron--strain life fatigue database.