Question: what is the difference between 308 and 309 welding rod?
Answer: Both the 308 and the 309 have an All-Weld-Metal Tensile requirement of 80ksi minimum, but the 309 is usually recommended for welding stainless to dissimilar metals. To add to what Chuck has said, the higher chromium content in 309 promotes the formation of ferrite and increases resistance to oxidation and corrosion.