Sliding wear behaviour of salt bath nitrided 316LN austenitic stainless steel

Abstract

The wear behaviour of AISI 316LN austenitic stainless steel has been studied by varying the duration of nitriding. AISI 316LN steel was nitrided using salt bath nitriding which consist of a mixture of 70:30 ratio of alkaline cynates and carbonates. Nitriding was carried out for two time durations namely 60 min and 100 min. Pin-on-Disc wear test were carried out for both the untreated and treated sample at room temperature. The wear parameters were changed to understand the wear mechanism of AISI 316LN steel along with the nitrided sample by varying the sliding distance for 250 m, 500 m and 1000 m. Due to the presence of different wear mechanism the rate of wear varies as a function of sliding distance. For untreated sample the wear mechanism was dominant with adhesion, abrasion and plastic deformation. An optical micrograph, X-ray diffraction analysis, wear morphology, hardness measurement and surface roughness were carried out. Due to the presence of compound layer as a result of nitriding AISI 316LN austenitic stainless steel, the mechanism of wear was restricted to abrasive wear. Untreated specimens have more significant wear loss when compared to treated specimen as work hardening and an increase in hardness of wear track resulted in material pull out. Stability of the compound layer is achieved as a result of longer duration of nitriding. Abrasive wear is resisted to a greater extend due the availability of compound layer. AISI 316LN steel which was nitrided for 100 min exhibited a more stable compound layer when compared to the same nitrided for 60 min.