Charactéristiques mécaniques
L'acier inoxydable austénitique a la limite d'élasticité la plus basse de tous les aciers. Par conséquent, du point de vue des propriétés mécaniques, les aciers inoxydables austénitiques ne sont pas le meilleur matériau pour la tige de soupape, car pour assurer une certaine résistance, le diamètre de la tige de soupape doit être augmenté. La limite d'élasticité ne peut pas être augmentée par traitement thermique, mais peut être obtenue par formage à froid.
performances magnétiques
Due to the wide application of austenitic stainless steel, many of us have false impression that all stainless steel has no magnetic. For austenitic stainless steel, this can be understood as non-magnetic, because it is true that the forged steels have no magnetic after quenched, but SS304 will be somewhat magnetic after cold forming. For casting stainless steel, if the material is 100 percent Austenitic stainless steel, then it is no magnetic.
Acier inoxydable à faible teneur en carbone
The corrosion resistance of austenitic stainless steel comes from the oxidation chrome protective layer formed on metal surface. If the material is heated to a high temperature of 450 degree to 900 degree , the structure of the material will change, and carbide will form along the edge of the crystal. In this way, the protective layer of magnesium oxide cannot be formed on the edge of the crystal, which decreases the corrosion resistance. This corrosion is called "intergranular corrosion".
As a result, 304L stainless steel and 316L stainless steel were developed to combat this corrosion. Both 304L stainless steel and 316L stainless steel have lower carbon content, so there will be no carbonization problem, and the "Intergranular corrosion" will not occur.
Il convient de noter que la sensibilité entre une corrosion intergranulaire plus élevée ne signifie pas que les matériaux à faible teneur en carbone sont plus faciles à corroder. Dans un environnement à haute teneur en chlorure, cette sensibilité est plus élevée.
Please note that this phenomenon is due to high temperature (450 degree -9000c), and usually soldering is the direct reason to reach such high temperature. For soft seat butterfly valve, since we do not proceed welding on the valve plate, it doesn't make much sense to use low carbon stainless steel, while most specs will require also 304L stainless steel or 316L stainless steel.
Pourquoi l'acier inoxydable rouille-t-il aussi ?
Why does stainless steel also rust? When brown rust spots appear on the surface of stainless steel pipes, people were amazed: "Stainless steel is not rusted, the rusted one is not stainless steel, it may be some problems with the steel", while it is just false conception of stainless steel, because stainless steel is also rusted under specific circumstances.
