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.

A carbide cutting tool is widely used in machining process due to its availability and being cheaper than a better performance cutting tool, such as cubic boron nitride. The carbide cutting tool also has substantial hardness and toughness that is suitable to be applied in intermittent cutting. This paper presents the case study of a wear mechanism experienced on the cutting edge of the coated and uncoated carbide tools in turning and milling processes. The wear mechanisms of carbide cutting tools were investigated in machining Inconel 718, titanium alloy Ti–6Al–4V extra-low interstitial, and aluminum metal matrix composite (AlSi/AlN MMC) at their high cutting speed regime. The tools failed primarily due to wear on the flank and rake faces. The failure mode of the carbide cutting tools was similar regardless of the machining operations and coating is believed to enhance the tool life, but once removed, the tool fails similar to that with the uncoated tool.