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Microstructure and Mechanical Analyses of Laser Clad Stainless Steel and Stainless Steel–SiCp Mixture Powders on a Mild Steel Substrate
H. A. Sabour, M. A. Taha, K. A. Gany, A. Farid, A. G. Youssef and Y. H. Elbashar

Improving the mechanical properties of mild steel by adding hard ceramic particles using laser cladding technology is the interest of recent research. Described herein are 304L stainless steel and its composites with 5, 10 and 15 wt.% SiCp clad on a mild steel substrate using a Nd:YAG laser. The influence of processing parameters on clad layer metallurgical characterization (microstructure, dissolution of SiCp, phases and distribution of elements) and mechanical properties (hardness and wear resistance) are studied. The results indicate that the main structure of both the 304L stainless steel and its composites is austenite dendrite structure. For stainless steel composites, the SiCp is partially dissolved which led to form a synthetic metal matrix composite (MMC) with stainless steel and secondary precipitations of Fe2Si and Cr7C3. The horizontal distribution of alloying elements in the clad area, parallel to the top surface, indicate homogeneity through the clad layer; the vertical distribution of alloying elements, from the top surface of the clad layer to the substrate, indicate the dilution of alloying elements between the substrate and clad layer areas. The distribution analysis of alloying elements in the clad area indicate homogeneity through the clad layer and the entrance of alloying elements between the substrate and the dilution area. The hardness of mild steel substrate and the 304L stainless steel clad layer are 160 and 210 Hv, respectively. With the addition of 5, 10 and 15 wt.% SiCp results in a continuous increase in hardness to 320, 400 and 650 Hv, successively, at a laser energy density of 82.0 J/mm2. Wear rate measurements proved the realizing of the major goal of this work, which is the improvement of wear resistance.

Keywords: Nd:YAG laser, mild steel, 304L stainless steel, SiC, synthetic metal matrix composite (MMC), laser cladding, microstructure, hardness, wear

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