Hobart SubCOR SL 731 description: SubCOR SL 731 is a seamless, carbon-steel, cored wire for submerged arc-welding for welding carbon/non-alloyed steels, and some low-alloy steels. SubCOR SL 731 is specially formulated to provide improved weld metal toughness and ductility compared to solid wire alternatives such as EM12KS, EM13KS, EH12K, etc.