NOREM wear-resistant, iron-based hard-facing alloys: Final report

Wear-resistance cobalt-free hardfacing alloysare needed to replace the cobalt-base alloysused to hardfacenuclear valves in order to reduce the exposure of maintenance personnel. Some thirty heats of cast iron-base alloyswere prepared and characterized. Selected heats were prepared and applied as hardfacing overlayson austenitic steel substrates using both GTA and PTA welding processes. Some of the iron-base alloysexhibited gallingwear resistance as high as that of cobalt-base standards both in the cast condition and in the PTA overlays. Hardness, mechanical properties, and gallingwear resistance were determined on weld overlaysand on cast alloys. Dilution and thermal expansivity were determined for weld overlays. X-ray diffraction and scanning electron microscopy were used to determine the alloys' microstructures. Other commercially available alloyswere tested for gallingwear resistance and compared to iron-base alloys. 7 refs., 2 figs., 2 tabs.