CONICET | Buscador de Institutos y Recursos Humanos

Cracks normallyoccur during machining in interrupted cutting conditions (e.g.,milling processes) in which cemented carbides are underthermo-mechanical cycling loads. In the presence of cooling media(wet machining) cemented carbides develop fatigue induced cracksparallel to the cutting edge; which lead to chipping and reduced toollife. The formation and propagation of these cracks is accelerated bychemical attack of the binder phase. A series ofexperimental techniques have been employed in order to understand theeffect of microstructure and chemical composition on corrosion andfatigue damage of cemented carbides. The corrosion resistance incooling fluid solution of cemented carbides with different binderalloys has been characterized by means of potentiodynamic anodiccurves and the attacked surfaces have been analyzed by SEM and EDS.In order to have a more real picture of the inserts in cuttingsituation, different substrates were coated with TiCN or ZrCN.Contact fatiguetests were done in dry and wet conditions and different crack typeshave been observed using SEM/FIB analysis. In order to evaluate thewhole crack shape and thickness, cross sections were re-polished bymeans of FIB, revealing the cracks shapes. EDS mapping ofthe affected areas evidences the crack propagation is due to binderphase dissolution during wet conditions. Additionally somemilling machining tests were done on real inserts and the cracks wereevaluated from cross sections by optical microscopy.p { margin-bottom: 0.25cm; direction: ltr; line-height: 115%; text-align: left; }