Effect of Austempering Heat Treatment Parameters on the Microstructure and Dry Sliding Wear Behaviour of AISI 9255 High Silicon Steel

Abstract

The present investigation is focused to evaluate the dry sliding wear behavior of AISI 9255 high silicon steel austempered at different temperatures and durations. Here three batches of cylindrical test specimens were prepared from as-received high silicon steel and were austenitized at 900 �C for 30 minutes, followed by austempering heat treatment in a salt bath maintained at temperatures 300, 350 and 400 oC for durations between 1 to 4 hours. The samples after austempering were cooled to room temperature in open air. The microstructural analysis was done by using optical microscopy, scanning electron microscopy and x-ray diffraction (XRD) and also hardness test was done using micro vickers hardness tester and correlated to the specific wear rate of the austempered steel. Results indicate that specific wear rate decreases with increase in austempering time and increases with increasing temperature. Specific wear rate was found to be lowest at austempering temperature of 300 �C, which exhibits lower ausferritic structure having high hardness. At higher austempering temperature 400 �C, specific wear rate was observed to be high because of upper ausferritic microstructure having lower hardness. Results reveal that the material with high hardness shows high wear resistance i.e., the one austempered at 300 �C showed superior sliding wear resistance than the rest. � 2017 Elsevier Ltd.