The macro-and micro-geometrical characteristics of the surface of porous sintered steel parts were investigated. While the macro-geometry influences waviness and geometrical precision, that means functionality and assembly, micro-geometry affects roughness and surface bearing section and, in turn, fatigue, corrosion and wear resistance. During compaction, the powder in contact to the die is exposed to different forces and constrain with respect to that in contact to the punches. As a consequence, the punches and die surfaces show different characteristics, which have been highlighted. Moreover, surface porosity is greater than the core porosity. The characterization was carried out on low alloyed Cr-Mn steels, which have been compacted to different green densities and sintered at different temperatures, to evaluate their effect on the geometrical characteristics of the surfaces.
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