Effect of roller burnishing process on surface roughness, microhardness and high-cycle fatigue behaviour of Inconel 718 alloy

Abstract This study investigates the effects of burnishing force, feed rate and the number of passes on surface roughness, microhardness and fatigue life of conventionally turned Inconel 718 alloy via the roller burnishing (RB) method. The process parameters were evaluated at four levels using a Taguchi L16 experimental design. To improve the statistical reliability of the fatigue analysis, fatigue tests for each experimental condition were repeated three times ( n = 3). Compared to untreated specimens, roller burnished specimens exhibited up to a 1018% improvement in fatigue life, while the average fatigue life improvement was calculated as 383%. In addition, the surface roughness decreased from 3.2 µm to 0.12 µm, whereas the microhardness increased from 288 HV to 418 HV after the burnishing process. According to the ANOVA results, burnishing force was identified as the most influential parameter affecting fatigue life, with a contribution ratio of 93.53%. The obtained results demonstrate that RB is an effective surface enhancement method for improving the fatigue performance and surface integrity of Inconel 718 components used in demanding engineering applications.