Steels with 10 to 17% Chromium, low Carbon and Nickel content result in a microstructure of tough martensite and achieve strengths of up to 1700 MPa by alloying with Copper or Aluminium with simple low distortion and hardening treatment. Preferred areas of application under corrosive environments are aerospace, the oil and gas industry and measurement and control technology.
This special subgroup of martensitic stainless steels, the soft martensitic and precipitation-hardenable stainless steels (supermartensites) achieve the martensitic microstructure via higher Ni contents with simultaneously low C and N contents. This is associated with higher toughness, better weldability and, due to lower binding of Cr by C, also higher corrosion resistance. Alloying elements such as Cu, Ti and Al are used to achieve precipitation-hardenable alloy systems (PH steels) and increase strength through the precipitation of intermetallic phases from the martensite in the course of a simple, low-dimensional heat treatment.
Common applications for such steels are in mechanical engineering, e.g. fastening elements, shafts, springs, gears and lightweight construction, e.g. in the aerospace industry.