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The present work aims to characterize the microstructure of valvetrain camshaft lobes that are currently applied in the automotive industry, obtained by different processing routes. The cam lobe microstructure has been assessed by microscopy, whereas the mechanical properties by hardness profile measurements on the surface region. Microconstituents type and form, composing the final microstructure at the cam lobe work region, are defined by the casting route and/or post-heat treatment process other than alloy chemical composition, so that knowledge and control of processing route is vital to assure suitable valvetrain system assembly performance and durability. Most of the mechanical solicitations on the part occur at the interface between cam and follower; the actual contact area is significantly smaller than the apparent area. As a result, the microstructure at and near the surface performs a direct role on the performance of the valvetrain, cam lobe and its counterpart.

This work consists in a study on the influence of gray cast iron graphite shape on the localized wear occurrence in engine block cylinders. The four cylinder automotive spark ignition internal combustion engine has been submitted to a complete dynamometer engine durability test. The tested engine is the one equipped with the flexible fuel technology, which is capable to work with both gasoline/ethanol fuels, in any mixture proportion. The specimen taken from the end-of-test engine block has been submitted to a 2D profilometer analysis, where region of localized wear at top dead center (TDC) zone was identified. The local wear region has been properly prepared epared and characterized through both scanning electronic microscopy (SEM) and metallography technics.