Oerlikon Inertfil 309L description: INERTFIL 309L is used for the welding of stainless steels to mild and medium tensile steels. It is used for depositing intermediate layers on steel prior to depositing 308 grade stainless steel. Also used for the welding of clad steels where service temperatures are below 300C. The weld metal has a delta-ferrite content of 12% resulting in a high resistance to hot cracking. Stainless steel wire for welding steels of the same composition and to weld dissimilar steels. 300C maximum operating temperature.