Laser Cladding of Ni – Mo Alloys for Hardfacing Applications
G.L. Goswami, Santosh Kumar, R. Galun and B.L. Mordike
Most common hardfacing alloys are of stellite family, which are cobalt base alloys and borides are also being developed for the same purpose. Both cobalt and boron are not suitable in nuclear industry as cobalt becomes radioactive after irradiation and boron is a neutron poison. Therefore, there is a need to develop cobalt and boron free hardfacing alloys for nuclear application. It has been attempted to develop cobalt – boron free, nickel – molybdenum hardfacing alloys for laser cladding.
Three alloy compositions, (Ni-5Al)-5Mo, (Ni-5Al)-15Mo and Ni-15Cr-30Mo have been cladded onto 0.15% C-steel by blown powder laser cladding process. Stellite-6 was also cladded by same method for comparison. The process parameters have been optimized to obtain defect free claddings. The cladded samples were characterized by optical microscopy, microhardness measurements across the substrate – clad layer interface for determining the extent of dilution zone and dry abrasion test by pin on disc method against 600 grit size SiC abrasive paper. The Ni-15Cr-30Mo claddings emerge as promising alternative of stellite-6 cladding.