| This paper includes a basic study of the applicability and feasibility of the laser surface alloying technique for enhancing the surface properties of materials, which are used in severe corrosion and erosion environments. Further, the effects of laser processing parameters(such as beam power, beam size, scanning speed, powder feed rate, gas flow rate) on the dimension and shape of the alloyed layer were also included. The dimension and shape of the alloyed layer were found to have more or less exponential relationship with processing parameters, especially with the power intensity, powder feed rate and scanning speed. Microstructures of the laser alloyed layer consisted of three different layers. In the layer I, adjacent to the bond line, applied Cr₃C₄ completely dissolved and mixed with the melted substrate Which transformed to C saturated austenite matrix and carbides (Cr_7C₃ and Cr_(23)C_6) along dendrite boundaries during rapid cooling. In the layer II which is a mid-region of the alloyed layer, Cr₃C₂ also dissolved but did not appear to mix with the substrate completely and transformed as nonequilibrium phase of M₃C₂ during cooling. In the layer III, some of the Cr₃C₂ were not dissolved and embedded in the C, Fe enriched austenitic solid solution. |
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