Fatigue behaviour of thin coated Al 7075 alloy with low temperature PVD coatings

7075-T6 is one of the most performing aluminium alloys, considering its mechanical properties and good fatigue behaviour. In this work the influence of WC/C and DLC PVD coatings on the fatigue behaviour was investigated by rotating bending tests at 2·105 cycles. The fatigue behaviour of polished and untreated specimens was considered as reference. In order to decouple the effect of the deposition temperature from the coating one, some uncoated specimens were submitted to the thermal cycles of the WC/C and DLC processes and then tested under fatigue loading. Fatigue life was determined using a step-loading technique. SEM micrographs of the fracture surfaces were taken in order to characterize the fatigue mechanisms of coated and uncoated specimens.