This study shows the effect of heat treatment on the torsion aspects of D2 alloy steel, in addition further analysis using ANSYS11 software w as used in investigation. Test specimens were prepared using high accurate machines (CNC) however, hardening at different austenite temperature (during hardening) namely 1070, 1040, 1010 and 980ºC was studied followed by tempering process at 540ºC . It was found that there was a direct relation between the micro hardness magnitude and the austenite temperature, the maximum was 66.1% that achieved at 1070ºC. This finding was significant because there is a great enhancement in the ability of D2 alloy steel to sustain high torsion loads, where the maximum was 191.1% that achieved at 1070ºC.