Microstructural characterization of the laser clad 316L+SiC composite coating

Abstract

In this work the SS316L + SiC Metal Matrix Composites (MMCs) was characterized. Different amount of Silicon Carbide (SiC) was added as reinforcements in a matrix of 316L Stainless Steel (SS316L): 10% in volume and 20% in volume. The composites were produced by Laser Cladding (LC). An evolution of the characteristics of the cladded deposit was observed with the change of LC process parameters, such as power, scanning speed and powders utilized. For the production of SS316L + 20% SiC deposit the powders were used in original (as-produced) and milled conditions. While for the SS316L + 10% deposit only original powders were utilized. The deposits with 10% in volume of original SiC powders and with 20% in volume of milled SiC powders exhibit a compact structure with absence of porosity and/or cracks, and good interaction with the substrate. The characterization was made by means of Optical Microscope (OM), Scanning Electron Microscope (SEM), Differential Thermal Analysis (DTA), Thermo Gravimetry Analysis (TGA), Macro-hardness tests and chemical analysis. The powders of the two different compositions and after the milling process were characterized, especially by different thermal analysis and microscope observations. Considering their characteristic, the best condition for the Additive Manufacturing (AM) process was chosen and the samples were fabricated by LC. The microstructural characterization on the deposits revealed the formation of carbides that reinforce the matrix. The morphology and the composition of phases of the different deposits were compared by using microscope observations and thermal analyses.