Stainless 418 (Greek Ascoloy®) is a chromium-nickel-tungsten martensitic alloy for services up to 1200 °F.  418 is a deep hardening grade used for application where high resistance to tempering and stress-corrosion cracking are needed.  Stainless 418 can be found in discs in turbine engines, jet engine parts and turbine diffuser components.