Castings Made With Hard-particle Dispersions and Facecoats.
U.S. BoM, Albany Research Center, Albany, Oregon, NTIS: PB/86-151875 :23 pages
Ingots with hard-particle dispersions were produced by vacuum arc melting hollow steel cylinders containing compacted hard particles. Attempts to disperse cr3c2, b4c, or wc in aisi 4130 and 4340 steel resulted in the dissociation of these carbides and the formation of new phases within solid solutions containing the dissolved elements, tic and tib2 additions remained intact as discrete particles dispersed throughout the matrix but failed to yield significantly increased wear resistance. Cast-on hard facings were produced by casting aisi 4340 steel into investment molds with hard particles adhered to the mold inner faces. Using the lost-wax investment molding process, together with vacuum arc melting and cold-mold centrifugal casting, conical coal cutter bits of the type used on continuous mining machines were produced with cast-on hard facings. Essentially void-free and tightly bonded hard facings of cr3c2, cr7c3, and wc were achieved, but tic, b4c, and tib2 hard facings were marked by gas-related defects and discontinuous interfacial bonding. The chromium and tungsten carbide facings proved to be too thin to provide notable protection to substrates.
NTIS Accession No.
U.S. Bureau of Mines Albany Research Center, Albany, Oregon, NTIS: PB/86-151875