Weld Mold 919 description: Weld Mold 919 is a typical AISI 4340 nickel, chrome, molybdenum carbon steel alloy. This material has shock resistant properties when used on cold working units where a high polish is necessary. A versatile product when a medium hard, tough weld deposit is required. May be used on such units as die cast dies, crankshafts, gears, axles, forgings, castings, and for build up prior to overlaying with harder alloys. Weld deposits respond to the heat treatment of standard AISI 4340 steels.