In this work, the effect of the torsion process angle of twist and distance from the center of cylindrical bars on the microhardness profile of annealed AISI 1045 steel was studied. The results showed that the microhardness increase with the evaluated parameters and the hardening is related to the plastic deformation caused by the process rather than by microstructural transformations. Based on the experimental results, ANOVA-Pareto analysis was conducted proving that the angle of twist is the most influential control factor (59.35%) among the parameters investigated. Finally, a model to predict the microhardness profile from the torsion process is presented.