309S is a free-cutting stainless steel containing sulphur, which is mainly used in situations requiring free-cutting and high surface finish.

 

309S is a variant of 309 stainless steel with low carbon content. It is used for welding occasions. Lower carbon content minimizes the amount of carbides precipitated in the heat affected zone near the weld, and the precipitation of carbides may lead to intergranular corrosion (welding corrosion) of stainless steel in some environments.

Chemical Composition of 309S Stainless Steel
chemical composition	content
C	≤0.08
Si	≤1.0
Mn	≤2.0
Cr	22.0-24.0
Ni	12.0-15.0
S	≤0.03
P	≤0.045