Effect of Density on the Machinability of Fe-C-Mo PM Low-Alloy Steel during Surface Grinding

Low-alloy steels prepared by PM methods are widely used in the automotive industry and commercial machinery to manufacture components for actual applications. The unique feature of PM materials is densification through deformation, which significantly enhances the mechanical properties of finished items. Machinability defines the way a material behaves during processing. Surface grinding is one of the traditional finishing processes, which may provide a better surface finish and narrow dimensional tolerance for machined components. The addition of molybdenum to low-alloy steels increases mechanical strength and machinability due to the nature of the alloying element. In this context, current experimental work focuses on the effect of densification on the machinability of the sintered Fe-0.5% C-2% Mo low-alloy steel. One sample was retained in the sintered state for the study, while four others were densified at different levels by uniaxial compaction. In this case, the maximum density of the pre-form was determined by the appearance of lateral cracks on the surface during the application of the incremental axial load for the densification process. Three sintered alloy steel preforms were subjected to cold upsetting by progressively applying three intermediate uniaxial loads. The density of as-sintered and deformed samples was measured according to Archimedes' principle. The surface grinding was performed on the as-sintered and densified specimens at constant machining parameters. After that, the surface roughness and hardness values were measured. It is found that an increase in density improved surface finish and hardness values of the preforms. The microstructure and surface morphology of the ground samples were also analyzed.