Investıgatıon on wear behaviour of duplex surface treated AISI 8620 steel with plasma nitriding and pack boriding

In this study plasma nitriding and subsequent boronizing surface processes were applied on to AISI 8620 steel. The samples were cleaned and placed into the plasma container and the container air was discharged until a pressure of 2,5X10 -2 mbar was attained. Before the nitriding process, the samples were subjected to H2 gas plasma for 30 minutes under a pressure of 5 mbar. Plasma nitriding was performed at a temperature of 500 oC, using a vacuum of 5 mbar in 50 % H2 - 50 % N2 gas mixture for a duration of 5 hours.Some of the plasma nitrided samples were boronized before and the rest was boronized after the white layer was removed. Boronizing process was performed in Ekabor2 powder at 800 and 900 oC in an electric oven for durations of 1, 3 and 5 hours. Sections were cut from the samples to which double surface process was applied; they were sandpapered on 240 ? 1000 grit sandpapers and polished with 0.1 µm alumina suspension. The samples which have been prepared metallographically were etched with 3% of nital. The thickness of the layers was measured with the help of an apparatus connected to the optical microscope (Olympus BX?60). The microhardness measurements from the section were performed inwards from the surface under a load of 100 gr. The XRD analysis was carried out on the samples by using CuK? radiation. Tribological tests were performed under a load of 10 N at a distance of 1000 metres with AISI 52100 ball in an unlubrication environment.