“…When analyzing the microhardness result, as illustrated in Figure 3 , it is verified that all samples have a surface hardness bigger than the sample of AISI 6160 steel that did not undergo treatment; this was already expected, both for what was discussed in the diffraction results’ X‐rays, as indicated in the literature. [ 4,15,26,27,29,40 ] The presence of phases such as FeN, Fe 2 N, CrN, and expanded austenite promotes an increase in surface hardness in metallic materials, specifically ferrous alloys that undergo a nitriding process. [ 1–3,29,38,47,56–60 ] Considering the deviation in the samples, it is possible to verify that they all had, on average, a very similar surface hardness value, and the more significant variation in the samples that underwent nitriding at 500 °C is due to the precipitation of nitrides and the inhomogeneity of these precipitates on the surface of the samples.…”