Empirical Modeling of Residual Stress Profile in Machining Nickel-based Superalloys Using the Sinusoidal Decay Function

After machining nickel-based superalloys, tensile surface residual stresses can cause end-product issues such as fatigue failure. Modeling the residual stress profile is currently tedious and inaccurate. This study introduces a new method of understanding the residual stress profile in terms of quantifiable key measures: peak tensile stress at the surface, magnitude and depth of peak compressive stress, and depth at which residual stress becomes near-zero. Experiments in turning IN-100 and milling GTD-111 have been conducted and subsequent X-ray Diffraction measurements have been utilized to obtain residual stress profiles. Using a sinusoidal decay function fitted to measured residual stress profiles, these four key profile measures are extracted and then the effects of process parameters such as cutting speed, feed, cutting edge radius, and tool coating on these measures are investigated.