Structural evolution in a synthetically produced ultrafine grained low carbon steel

Abstract

In this work, low carbon of extremely fine grain structure was produced by mechanical alloying of powders of iron and activated charcoal with minor addition of copper (Cu); mechanically alloyed powder was consolidated by spark plasma sintering to obtain a high-density compact. The steel so produced was subsequently subjected to forging followed by normalizing. The characterization was carried out by means of nanoparticle size analyzer, X-ray diffraction, optical microscopy, scanning electron microscopy, transmission electron microscopy, and Vickers microhardness testing. The microhardness value obtained for the steel was found to be significantly high and comparable with that of nanocrystalline/ultrafine grained steels produced by other routes. The increased hardness resulted from the smaller grain size and presence of finely dispersed ultra small sized copper and cementite precipitates.Keywords Fine grained ultra high hardness steel · Mechanical alloying · Grain growth inhibitor · Spark plasma sintering · Precipitation · Activated charcoal Abbreviations HEBM High energy ball milling AC Activated carbon SPS