SYNTHESIS OF SUBMICROMETER-GRAINED-ULTRAHIGH-CARBON ON STEEL CONTAINING 10-PERCENT ALUMINUM BY BALL-MILLING OF POWDERS

An ultrahigh-carbon (1.25 wt. %) steel alloy containing 10 wt. % alumi num (UHCS-10Al) was processed by a powder metallurgy technique. Gas-at omized powders were subjected to ball-milling in an attritor in order to obtain a submicrometer grain size. Powder material was consolidated by both hot isostatic pressing (HIP) and by hot isopressure extrusion (HIE). Bulk material with submicrometer grain sizes was produced from attrited powders. The chemical composition and microstructure of this material are characterized at each processing step, from atomization through consolidation. Tensile tests show that a high strength results from the submicrometer grain size produced in the bulk material.