309 stainless steel Plate, 309S stainless steel - S30908 (American AISI, ASTM) 309S. The steel mill produces more 309S stainless steel, which is better in corrosion resistance and high-temperature resistance. Can withstand 980°C high temperature. Mainly used in boilers, chemicals and other industries. 309 stainless steel plate does not contain sulfur S content compared to 309S.