The impact of various cooling environments on the distribution of macroscopic residual stresses in near-surface layers of ground steels

Grinding often plays the role of final machining, and, therefore, its parameters significantly affect the properties of the treated surface. In this study, the state of surface residual stresses (RSs) and their depth distribution into the bulk is investigated with respect to various cooling environments during grinding. In order to acquire complete stress tensors, the sample surfaces were analysed using the X-ray diffraction technique. Since ɛφψ(sin2 ψ) dependences in grinding direction are non-linear and exhibit psi-splitting, the method proposed by Dölle and Hauk was used to evaluate the tensors of anisotropic triaxial state of RS. The effective penetration depth of Cr Kα X-ray radiation into ferrous materials is approximately 4 μm, and, therefore, removal of surface layers is necessary in order to pinpoint the distribution of RSs beneath the surface. The process of electro-chemical polishing ensures that the impact of material removal causes minimal or negligible mechanical and thermal distortions of the investigated state of stress.