A three-dimensional analytical model to predict the thermo-metallurgical effects within the surface layer during grinding and grind-hardening

The high amount of energy input during machining processes with geometrically undefined cutting edges, such as grinding, requires the knowledge of the transient temperature field within the machined surface to avoid thermal damages of the workpiece due to thermal-induced residual tensile stresses or softening for instance. An approach to use the heat generated during grinding is the grind-hardening process, which allows for the process-integrated martensitic surface layer hardening of the workpiece. Because of the used simplifications, for example two-dimensionality, existing approaches to calculate the temperature fields during wet grinding cannot be successfully utilized to predict the phase transformations and the resulting hardened surface layer due to grind-hardening. This paper presents an analytical model, which enables to calculate a three-dimensional temperature field due to grinding and grind-hardening using a triangular heat source and considering the effect of the grinding fluid. Based on the transient temperature distribution, the phase transformation within the surface layer and the resulting hardened layer thickness are determined also using analytical models. The analytical method is validated and analyzed comparing the results with measured ones and with those calculated using the finite element analysis. Thereby, the presented approach allows for the efficient prediction of the thermo-metallurgical effects within the surface layer during grinding and grind-hardening.