Haynes M418 RTW description: HAYNES M418 RTW filler metal is used for the gas metal arc, gas tungsten arc and submerged arc welding of M400, K-500 and other nickel-copper alloys. The weld metal has good corrosion resistance to many media including sea water and reducing acids. The alloy can be used for the overlay and cladding of steels, but care should be taken to determine if a butter layer of ERNi-1 is needed fi rst. The RTW fi ller metal fi nish on the spooled wire promotes smooth feeding through welding equipment and reduced tip wear in contact tips.