Today, energy consumption and environmental issues are important topics in all industries around the globe. However, quality is in direct proportion with energy consumption, since better surface finish means more energy consumption. The main objective of this work is minimizing both surface roughness and power consumption by estimating the optimum machining parameters. In this study, turning tests were carried out on three different hardened AISI 1040 steels (10, 15, 20 HRC) at three different depths of cuts (1.2, 2.4, 3.6 mm), feed rates (0.15, 0.25, 0.35 mm x rev(-1)) and cutting speeds (120, 140, 160 m x min(-1)) without coolant. The effects of cutting parameters and workpieces hardness on surface roughness, sound level and power consumption were examined. These analyses were conducted using a full factorial experimental design method. The response surface methodology and analysis of variance were also used to determine the effects of input parameters on the response variables. Experimental results showed that an increase in the feed rate value causes an increase in the surface roughness, the sound level, and the power consumption values. The results of the presented work show that feed rate is the most effective machining parameter that affects surface roughness and power consumption. Following feed rate, depth of cut and cutting speed also have an important impact. Thus, decreasing the value of feed rate and depth of cut will reduce the amount of power consumption.