Stainless steels, handling and cleaning
If the steels are contains minimum 12 % Chromium alloy, ( and less then 0.12% Carbon ) then the steel became to be resistant for corrosion – then we callthem Anticorrosional steels.
The Chromium react with the Oxygen and build up a thin, but very solid Chromium-Oxide layer, what “close” the inner steel material from the corrosional environmentaleffects.
If the layer is scratched or damaged, and there is no pollution on the damaged area, the Chromium-Oxid layer would rebuild within 1-2 hour, depend on the humidity.
The Stainless steels areseparated into 4 different groups, by their material structures, depend on their amounts and type of alloys ( Cr, Ni, etc… ).
In the Grundfos Quality system there is a standard, GS… what declare whichsteels are allowed to change with each other, within one group. No other type of steel materials is allowed to use as instead.
The main groups.
- Ferritic anticorrosion steels: for ex: WNr:1.4301, what is resistant against waters and hot water. Good welding, good strength, smaller toughness.
- Austenitic anticorrosion steels: for ex.: WNr: 1.4359, what is resistant not only against water butalso acid, chloride, phosphorus, sulfurous environment. Good welding, good toughness, smaller strength.
- Duplex anticorrosion steels : ferritic + austenitic with very high alloy containments, whatis resistant against acid, chloride, phosphorus, sulfurous environment. Good toughness, good strength.
- Martensitic anticorrosion steels: Martensitic structure. Mainly for turbine structures. Veryhigh strength, small toughness.
Handling and cleaning:
- The Anticorrosional steels are normally supplied in “softened” ( less strength, less toughness, better cold forming and machiningproperties ) status, from the supplier. (Heat up to 1050 C and cooling fast – quenching. )
- The Anticorrosional steels has to be stored ( in long term storage ) separately from normal steels – not to...
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