Application of Response Surface Methodology to Experimentally Investigate the Dry Turning of Austempered Ductile Iron

Abstract

Austempered Ductile Iron (ADI) is basically grade of Ductile Iron (DI) formed due to austempering process. The excellent mechanical properties of ADI due to Ausferrite matrix resulted in a rapid increase in application of ADI in automotive, agriculture and construction industry. Austempering process offer ability to access to a wide range of characteristics with appropriate selection of heat treatment parameters. Post treatment machining of component is desire, to maintain geometrical tolerances and surface finish. The formation of carbide in matrix while alloying due to molybdenum and manganese and strain induce transformation (SIT) of austenite to martensite while machining making ADI difficult to further machine. In the present work, experimental investigations have been carried out into dry turning of ADI using response surface methodology. The performance of cemented carbide tool while machining ADI (austenitised at 850 °C for 2 hr, austempered at 350 °C for 1 hr) has been presented. The effects of speed, feed and depth of cut on cutting force, microhardness, tool wear and variation in chip formation have also been investigated. Empirical models of cutting force have been developed using response surface methodology. The adequacy of these models has been checked by using analysis of variance. The predictability of main cutting force has been found to be greater than 95 %. The main cutting force found to be influenced mainly by depth of cut while, tool wear by depth of cut and cutting speed.