Mckay Smootharc Plus 309L-16 description: A high alloy core wire that is low in carbon to reduce susceptibility to sensitization during high temperature service. Ideal for the out-of-position welding of austenitic stainless steels to unalloyed or low alloy steels. Delivers excellent welding performance and can also be used for welding buffer layers on unalloyed steels prior to joining to other austenitic stainless grade steels.