Perforated stainless steel sheet is essentially a low carbon steel which contains chromium at 10% or more by weight. The chromium content of the steel allows the formation of a rough, adherent, invisible, corrosion-resisting chromium oxide film on the steel surface. If damaged mechanically or chemically, this film is self-healing, providing that oxygen, even in very small amounts, is present.
Stainless steels can be divided into three basic groups based on their crystalline structure: austenitic, ferritic, and martensitic.
The most commonly perforated stainless steel types are mentioned below.
Austenitic stainless steels are non-magnetic non heat-treatable steels that are usually annealed and cold worked. Some austenitic steels tend to become slightly magnetic after cold working. Austenitic steels have excellent corrosion and heat resistance with good formability over a wide range of temperatures. Additions of molybdenum can increase the corrosion resistance.
Typical industry applications: Food equipment, chemical equipment, architectural applications
– 304 Low carbon modification of type 302 for restriction of carbide precipitation during welding.
– 304L Extra-low carbon modification of type 304 for further restriction of carbide precipitation during welding.
– 316 Higher corrosion resistance than types 302 and 304, high creep strength.
– 316L Extra low carbon modification of types 316, used in welded construction where intergranular carbide precipitation must be avoided.
– 321 Stabilized for welds subject to severe corrosive conditions and for service from 800 to 1600F
Ferritic stainless steels are magnetic non heat-treatable steels that contain chromium but not nickel. They have good heat and corrosion resistance, in particular sea water, and good resistance to stress-corrosion cracking. Their mechanical properties are not as strong as the austenitic grades, however they have better decorative appeal.
Typical industry applications: Automotive trim, cooking utensils
– 430 General purpose non-hardenable chromium type.
Martensitic grades are magnetic and can be hardened by heat treatment. They are not as corrosive resistant as austenitic or ferritic grades, but their hardness levels are among the highest of the all the stainless steels.
Typical industry applications: Fasteners, pump shafts, turbine blades
– 410 General purpose heat treatable type.