Hobart SDX S3Ni1Mo-EF3 description: SDX S3Ni1Mo-EF3 is a copper-coated, low-alloy, solid wire for submerged arc welding. The nominal nickel-molybdenum composition of SDX S3Ni1Mo-EF3 provides good low-temperature toughness and is suitable for welding many high-strength low-alloy (HSLA) steels. Hobart recommends using this wire with the following flux(es): SWX 150.