الفهرس 
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Abstract
Improving the mechanical properties of austenitic stainless steel by adding hard ceramic powder using rapid prototyping technology is a recent interest of researchers. In this research, SS304L powder is mixed with different percentages of SiC powder; 5, 10, and 15 wt. %, and deposited on a mild steel substrate using Nd: YAG laser machine.
The quality of deposited layers is analyzed by measuring geometrical dimensions and microscopic examination of defects. The influence of processing parameters on metallurgical characterization; microstructure, dissolution of SiC, phases, and distribution of elements, and mechanical properties; hardness and wear resistance, are studied.
The results show that high bonding of metal-ceramic layers is achieved by increasing the laser energy density. As increasing the heat input, the track characteristics; width, height, depth of penetration, and dilution, are increased, while the aspect ratio is decreased. Slight effects on the geometry of deposited layers are noticed at adding 5, 10, and 15 wt. % SiC.
The overlap ratios of tracks are increased at high laser energy density leading to enhancing the effective coating height and reducing the final post-processing cost. The percentages of defects; un-melted powder particles and pores are reduced at higher laser energy density. The optimum processing parameters are identified at laser power 800 w and scan speed 25 cm/min.
The main structure of both SS304L and its composites with SiC is an austenite dendrite structure. For composites, the SiC is partially dissolved and form a synthetic metal matrix composite with SS304L and secondary precipitations of Fe2Si and Cr7C3. The distribution of alloying elements in the deposited area indicates homogeneity.
The dilution of alloying elements can be noticed between the substrate and the mixing area. While the measurements of hardness for substrate and SS304L track record 160 and 210 Hv respectively, adding 5, 10, and 15 wt.% SiC reflects in a continuous increase of hardness to 320, 400, and 650 Hv successively, at a laser energy density of 82 J/mm2. Wear rate measurements proved the realizing of the major goal of this work, which is the improvement of wear resistance.