Investigation of Tribological Properties and Characterization of Borided AISI 420 and AISI 5120 Steels

In the present study, tribological and characterization properties of borides formed on AISI 420 martensitic stainless and AISI 5120 cementation steels have been investigated. The boride layer was characterized by optical microscopy, X-ray diffraction technique and the micro-Vickers hardness tester. X-ray diffraction analysis of boride layers on the surface of the steels revealed the existence of FeB, Fe2B and CrB compounds. The wear tests were carried out in a ball-disc arrangement under a dry friction condition at room temperature with an applied load of 10 N and with a sliding speed of 0.3 m/s at a sliding distance of 1,000 m. The wear surfaces of the steels were analyzed using a SEM microscopy and X-ray energy dispersive spectroscopy EDS. The results were compared with each other. It was observed that the friction coefficient of unborided and borided steels ranged from 0.42 to 0.63. The wear rate of the borided steels was found to be approximately five times lower the wear rate of the unborided steels.