Development of cobalt-free hard-facing alloys for nuclear applications: 1985 progress: Interim report

Cobalt-free hardfacing alloys are needed to replace cobalt-base Alloy No. 6, used in nuclear valves, in order to reduce the exposure of service personnel to radioactivity due to /sup 60/Co. A series of iron-base, cobalt-free alloys were prepared and applied as hardfacing overlays on austenitic steel substrates using both GTA and PTA welding processes. Hardness, mechanical properties, and galling wear resistance were determined on welded overlays as well as on cast alloys. Some of the iron-base alloys exhibited galling wear resistance as high as that of Alloy No. 6 both in the cast condition and in the PTA overlays. Other cobalt-free alloys, including long-range ordered (LRO) alloys, have been tested for galling wear resistance and compared to the iron-base alloys. Galling tests were also performed on the laser-remelted hardfacing deposits for evaluating the application of laser treatment to hardfacings on nuclear components.