Tribological behaviour and tool wear analyses in rough turning of large-scale parts of nuclear power plants using grooved coated insert

The tribological behaviour and tool wear mechanisms in rough turning, using coated grooved insert, of a large-scale part, made of 18MND5 steel used for steam generators of nuclear power plants, have been analysed. Characterisation of the insert rake face, using various techniques (SEM, EDS and Profilometer), has revealed an intense thermomechanical loading with wear localisation at particular zones, and formation of an adhered thin tribo-layer. A numerical model has been developed to predict finely the tool wear as revealed by experimental observations. The main findings concern the prediction of contact discontinuities and where the wear is highly localised as well as thermomechanical conditions causing observed phenomena, like adhesion of the workmaterial on some zones on the rake face. Contact discontinuities are attributed to the complex geometry (presence of concave zones) of the coated grooved insert, designed especially to reduce the tool-chip contact area and to promote the chip breakage. Other cutting parameters, like the specific cutting force and chip morphology parameters are also well predicted. This is a contribution to understand wear mechanisms occurring on complex cutting inserts at high material removal rate (moderate cutting speed, but high depth of cut and feed rate).