International Journal of Engineering and Technology

Many engineering applications demand materials with hard surface and tough core. In the present study, the enhancement of this combination of properties was achieved in aluminium alloy AA6061 by Severe Surface Mechanical Treatment (SSMT). The process parameters were optimized using Taguchi L9 orthogonal design of experiments. The size of shots, speed of revolution of shaft and duration of treatment were the parameters taken into consideration as they are directly related to the energy imparted to the surface during the process. The optimal levels were independently determined with reference to surface hardness and ultimate tensile strength of the material. The predicted optimal values of surface hardness and ultimate tensile strength were confirmed by experiments. Analysis of variance (ANOVA) showed that there is no significant difference in the contribution towards the hardness of the surface from these parameters, but in the case of ultimate tensile strength, the shot diameter was found to be more dominant than the other parameters. Results from optical microscopy and X-ray diffraction (XRD) studies were used to explain the enhancement of properties.