MTD 1 is a 4140 plate steel modified with slightly higher carbon and a vanadium addition. Vanadium improves graining refinement and, coupled with the higher carbon, promotes hardness and wear resistance. ArcelorMittal USA MTD steels comprise a family of pre-hardened alloy plate steels developed for a variety of mold, tool, and die applications. This datasheet provides information on composition. It also includes information on forming, machining, and joining. Filing Code: SA-793. Producer or source: ArcelorMittal USA, Plate.