Anodic plasma electrolytic nitrocarburising of Ti6Al4 V alloy (SMT31)

The structure of Ti6Al4 V alloy, its microhardness, surface roughness and corrosion resistance after anodic plasma electrolytic nitrocarburising (PEN/C) in an electrolyte containing carbamide and ammonium chloride were investigated. An X-ray diffractometer and a scanning electron microscopy were used to characterise the phase composition and structure of the modified surface. The effect of processing temperature on the corrosion resistance of the PEN/C samples was examined by means of potentiodynamic polarisation in Ringer's solution. It was found that the PEN/C provides the formation of the external oxide layer (rutile) and a solid solution of carbon and nitrogen in titanium with martensite structure after quenching in the electrolyte. The microhardness of the layer is 740 HV; the surface roughness decreases from 1 to 0.63 μm. Corrosion resistance in Ringer's solution does not deteriorate after anodic PEN/C at low temperature.