Micro-abrasive wear study of a low-temperature plasma nitrided Inconel 625 superalloy

ABSTRACT In this study, the microabrasive wear of a plasma nitrided Inconel 625 superalloy was studied. Nitrogen supersaturation in the expanded FCC layer promoted hardening due to the higher compressive residual stresses. The results showed the formation of a nitrided layer consisting of nitrogen expanded FCC phase (γN) and CrN nitride, respectively. Friction coefficient, mechanical failure mode and critical loads for damaging the nitrided case, using the linear scratch test, were carried out at a linearly increased normal force. The scratch test results showed that the nitrided layer strongly decreased the apparent friction coefficient in comparison with the non-nitrided alloy. Tensile cracking was the prevalent mechanical failure mode of the nitrided layer. Microabrasion results showed that the nitriding layer improving the wear resistance. For the nitrided samples, wear coefficients were determined for the nitrided layer and the substrate, indicating a change in the wear volume loss rate with the test distance. GRAPHICAL ABSTRACT