ABRASION RESISTANCE OF IRON-BASED HARDFACING ALLOYS

A study was undertaken of numerous iron-based hardfacing compositions as are weld deposits (SMA, FCA and SA) to evaluate quantitatively thei r low-stress abrasion resistance as a function of composition and hard ness. The method of evaluation is the ASTM G65, Procedure A, dry sand/ rubber wheel test, determining weight loss after a fixed number of rev olutions of the wheel. A broad spectrum of deposits was prepared from commercial and experimental electrodes. One-, two-, and four-layer cla dding permitted examination of dilution effects. The compositions stud ied included buildup alloys, martensitic deposits, austenitic manganes e, primary austenite with austenite-carbide eutectic, near-eutectic au stenite-carbide, and primary carbides with austenite-carbide eutectic. Composition and abrasion resistance are determined generally on one, two, and four layers of hardfacing on mild steel. In all, about 200 ha rdfacing deposits were evaluated. The most important variable in deter mining low-stress abrasion resistance was found to be carbon content. Above about 4% carbon, numerous primary carbides are obtained and abra sion resistance is greatest. Hardness and chromium content (alloy cont ent) have, at best, secondary effects on abrasion resistance. Dilution has an important effect, often causing an alloy that consists of prim ary carbides in multiple layers to be primary austenite in the first l ayer, with resulting inferior abrasion resistance.