Optimization of Burnishing Parameters by DOE and Surface Roughness, Microstructure and Micro Hardness Characteristics of AA6061 Aluminium Alloy in T6 Condition

Surface finish and surface hardness of the components play vital role in quality of products/components, in general and failure resistance, in particular. One of the finishing process that involve surface plastic deformation and introduces compressive residual stresses and thereby improve fatigue resistance is “Burnishing”. Even though the burnishing process is widely employed, its process parameters were not systematically studied till date and not fully established for various important structural materials, including the present material of study the AA6061 aluminium alloy. The burnishing process parameters studied in this investigation include depth of cut, speed, feed, and number of tool passes. The data obtained from systematically conducted burnishing experiments are correlated with theoretical design using Taguchi method. Further, surface characterization was conducted using optical microscopy and XRD studies were employed to estimate the micro hardness and magnitude of residual stress. The study revealed a oneto-one correlation between various burnishing parameters and a peak in all the three parameters, viz. burnishing depth, average micro hardness and compressive residual stress levels at intermediate extent of burnishing (either after first or second pass) in AA6061 alloy.