Stainless steel types

Stainless steel types for every application

Stainless steels have traditionally been divided into categories since the microstructure has a decisive effect on the properties. The categories are assigned depending on the chemical composition and the manufacturing steps and parameters that determine the microstructure at room temperature.

Our stainless steel microstructure categories

Outokumpu’s stainless steels can be divided into different categories – the best steel for you depends on the application.

Stay up to date on microstructure group

What are the 4 types of stainless steel?

FERRITIC: 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 a very small, addition of nickel.

MARTENTISITIC AND PRECIPITATION HARDENING (PH): 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. For improved strength and hardenability they have a higher carbon content compared to other grades, and nitrogen is sometimes added to further improve strength.

DUPLEX: 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. The duplex grades contribute to high strength and high resistance to stress corrosion cracking. These grades also have a ferritic-austenitic microstructure, with a phase balance of approximately 50/50.

AUSTENITIC: Austenitic stainless steel series 200 and 300 have become a staple of a wide range of industries, such as chemicals, pharmaceuticals, food and drink, textiles, and pulp and paper. The austenitic grades have good to excellent corrosion resistance, as well as good formability and weldability. This is also the largest group and it is further divided into five sub-groups. These sub-groups are Cr-Mn grades, Cr-Ni grades, Cr-Ni-Mo grades, high performance austenitic grades and high temperature austenitic grades.