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Application of Cast-on Ferrochrome-based Hard Surfacings to Polystyrene Pattern Castings.
Hansen-JS; Jordan-RR; Gerdemann-SJ; Soltau-GF
MISSING :37 pages
To advance technology that can help conserve critical materials, the Bureau of Mines investigated a cast-on hard-surfacing technique that improves wear resistance and confines alloy additions to wear-prone surfaces. Wear-resistant material in powdered form is applied on a polystyrene pattern, the pattern is embedded in a mold of unbonded sand, and the wear-resistant material is transferred to a casting surface at the time of pouring. For low-stress abrasion, surfacings derived from high-carbon ferrochrome had higher wear resistance than did commercially available weld-deposited hard facings. The microstructure of the surfacings was typical of hypoeutectic white iron containing m7c3-type carbides. Free carbon added to the ferrochrome powder produced more m7c3 carbides than did material contained in surfacings made from ferrochrome alone, and improved the wear resistance. Several white iron powders with greatly reduced chromium contents also produced white iron surfacings containing m7c3 carbides. One surfacing derived from white iron powder had wear resistence equal to that of weld-deposited hard facings. Among the parameters investigated, surfacing thickness was found to have a major influence on solidification, diffusion of elements out of the surfacing, microstructure, and wear resistance. The results of field tests on bucket-wheel excavator teeth and plowshares with cast-on hard surfacing are given.
IH; Report of Investigations
Page last reviewed: September 2, 2020
Content source: National Institute for Occupational Safety and Health Education and Information Division