Magnetic ferritic stainless steel grades, also referred to as chromium steel grades, are easy to form and machine. They come in a wide range of attractive surface finishes, and support superior product design.
The standard ferritic grades are alloyed with chromium (11.2–19 %), but with no, or very small addition of nickel, thus they have a ferritic microstructure. As nickel is one of the most expensive alloying elements and has demonstrated high price volatility, the low nickel content of the ferritic grades make them more price stable compared to grades with high nickel content. Molybdenum is added to some grades to improve the corrosion resistance, while alloying with niobium and/or titanium improves the weldability.
Martensitic steel grades and precipitation hardening (PH) stainless steels are heat treatable and can therefore provide hardness and strength in a wide range of applications. Allowing to workability they are supplied in solution annealed condition. The downstream manufacturer performs final heat treatment to meet the mechanical properties required.
Martensitic stainless steel grades are basically Fe-Cr alloys with a higher carbon content than ferritics which enables them to harden on cooling in air, oil or water. Depending on grade and intended use, ductility is improved by tempering.
Outokumpu duplex stainless steel grades offer an excellent combination of strength and corrosion resistance, allowing you to significantly reduce material thickness and cost in a host of applications.
Duplex stainless steel grades have a ferritic-austenitic microstructure, with a phase balance of approximately 50% ferrite and 50% austenite. They combine many of the beneficial properties of ferritic and austenitic stainless steels. The duplex microstructure contributes to the high mechanical strength and high resistance to stress corrosion cracking.
The high strength of duplex steel grades is also a result of alloying with nitrogen. Other characteristic properties of duplex steel grades include good abrasion and erosion resistance, good fatigue resistance, high-energy absorption and low thermal expansion.