Surface hardening by in-situ grown composite layer on microalloyed steel employing TIG arcing process

Surface of microalloyed steel, hereafter referred as steel, has been modified by developing an in-situ grown composite case on its surface for improved hardness. It is done through surface melting by employing Tungsten Inert Gas (TIG) arcing. The hard reinforcements were made to grow in the surface matrix of steel through chemical reactions of the inorganic powders present in the applied coating and the molten base. The distribution and incorporation of these reinforcements were taken care by addition of Al and TiO₂ in the coating. Three different mixtures, comprising different proportions of Al and TiO₂, were prepared to develop a hybrid composite primarily containing Al₂O₃ and a small fraction of TiC along with other oxides as reinforcements. The modified particulate composite surface was analyzed under Vickers' micro-hardness tester confirming its significant improvement in hardness of the order of 1.88–2.24 times in comparison to that of the base metal, depending upon different chemistry of the powder mixture of the coating.