Anode plasma electrolytic boriding of medium carbon steel

The influence of the regimes of the anode plasma electrolytic boriding (PEB) of medium carbon steel on its structure and properties was investigated. An X-ray diffractometer, a scanning electron microscopy (SEM) and an optical microscope were used to characterize the phase composition of the modified layer and its surface morphology. Surface roughness was studied with the use of a profilometer-profilograph. The hardness of the treated and untreated samples was measured using a microhardness tester. A pin-on-disc tribometer was occupied to evaluate friction coefficient and wear rate of the untreated and treated samples at lubricated conditions. It is established that the influence of the processing regime on the thickness of the modified layer is explained by the competition of the boron diffusion and oxidation of steel sample. The electrolyte composition (10% ammonium chloride, 5% boric acid) and processing mode (850-900 °C, 5 min) of medium carbon steels allowing one to obtain the hardened surface layer up to 0.11 mm with microhardness 1800 HV and with decrease in the roughness of 3 times are proposed. The anode PEB could decrease friction coefficient and increase wear resistance of the medium carbon steel.