In support of its objective to decrease the use of critical materials through conservation and wear reduction, the Bureau of Mines investigated a hardsurfacing technique for use in mining and metallurgical processing equipment that confines alloy additions to wear-prone surfaces only and improves wear resistance. In the technique, powdered, wear-resistant material is pasted on a polystyrene pattern and transferred to a casting surface at the time of pouring. Vacuum is applied to a special casting flask to eliminate gas, maintain shape, and promote intimate contact between the powder and liquid metal. Three examples are cited in which high- carbon ferrochrome was applied as a surfacing material to aisi 1030 steel castings. Ferrochrome paste with less than 0.5% Polyvinyl acetate or cellulose binder resulted in hardsurfaces with few inclusions, few shrinkage voids, and no gas porosity. The hardsurfaces, containing m23c6 carbides, were fused and metallurgically bonded to the castings. A heat-treated ferrochrome- surfaced casting performed 27% better than water-quenched (rc 62) aisi 1060 steel in a test for low-stress abrasive wear. Work is continuing to improve process variables and to evaluate alternate hardsurfacing materials.
Am. Foundrymen's Soc. 87th Annu. Meeting, Afs Trans., V. 91, 1983, PP. 65-70