Finish Turning of FeCr17Ni2C0.2 Iron-based Sprayed Coatings: Influences of Substrate Preparation, Cutting Speed and Feed on the Coating and Surface Properties

摘要

Aluminum EN AW-5754 cylinders are pre-machined to provide different helical dovetail fine structures before APS coating with FeCr17Ni2C0.2. Tensile adhesive strength, hardness level and oxide content of the sprayed coatings are determined and set in relation to the geometrical features of the substrate surface. The coated specimens are machined by turning with different cutting speeds and feeds. After machining, the geometrical properties of the coating surfaces and the residual stresses of the surface layer are correlated with the varied cutting speed. Analyses are performed by tactile measurements, 3D laser scanning microscopy and XRD. The influence of the tool feed on the grain size near the coating surface is investigated by EBSD. The dovetail fine structure not only influences coating adhesion, but also affects hardness level and oxide content, which increased with a raising number of dovetail elements per surface area. Regarding finish machining, the surface values Ra, Rz, Rvk and Vvv tend to decrease with an increase in cutting speed. XRD analyses indicate that the absolute values of the principal stresses in the machined surface layer are independent of the cutting speed, but change their direction. An effect of the tool feed on the coating microstructures is not observed.