In this study, vermicular graphite cast iron samples were operationalized to Austempering process in two different temperatures (315 and 375 degrees C) and three different waiting periods (60, 120 and 180 min). According to the selected cutting tools and cutting parameters, the effect of Austempering temperature and waiting period on the lifetime of the tools was investigated. The tests were conducted on a CNC milling machine by using coated cementite carbide cutting tools. The tests on tool wear were done in dry conditions, in a cutting speed of 120 m/min, a pitch rate of 0.15 mm/dev, and a depth of cut of 1 mm. Tool wear, cutting forces and average surface roughness rates of milled surfaces; which were occurred during the milling process, were analyzed by using grey relation method. It is observed that an increase of Austempering temperature leads to an improvement between 2.15 and 2.85 times in the lifetime of tools. By using grey relational analysis, the highest cutting performance was obtained with the sample with the temperature of 375 degrees C, and a waiting period of 120 min. (C) 2019 Elsevier Ltd. All rights reserved.