Characterization and machinability of a high-silicon cast steel with ceramic and carbide tools

High-silicon cast steel exhibits good ductility and mechanical strength after microstructure transformation through an austempering heat treatment. The combination of these properties is outstanding in other steels, leading to emerging applications for high-silicon cast steel, such as in the railway sector. The Si content above 1.5% is a crucial factor for the formation of refined bainite and a dispersion of carbides in the matrix. This work involves the evaluation of the machinability of a steel alloy with 0.77% C and 1.77% Si using ceramic metal and ceramic tools. The alloy was cast, homogenized, austempered, and tempered. Subsequently, the high-silicon cast steel was characterized using scanning electron microscopy (SEM), hardness, tensile strength, and elongation. Machinability tests were conducted by turning and varying the cutting speed under dry cutting conditions with a constant feed rate. The analyzed output parameters were surface roughness, tool wear, and wear mechanisms. The increase in cutting speed directly influenced tool wear for all tools. The predominant wear mechanisms observed during the tests were abrasion and diffusion. The hard metal tool exhibited chipping on the cutting edge.