The surface characteristics of a machined product strongly influence its functional performance. During machining, the grain
size of the surface is frequently modified, thus the properties of the machined surface are different to that of the original bulk
material. These changes must be taken into account when modeling the surface integrity effects resulting from machining. In
the present work, grain size changes induced during turning of AA 7075-T651 (160 HV) alloy are modeled using the Finite
Element (FE) method and a user subroutine is implemented in the FE code to describe the microstructural change and to
simulate the dynamic recrystallization, with the consequent formation of new grains. In particular, a procedure utilizing the
Zener-Hollomon and Hall-Petch equations is implemented in the user subroutine to predict the evolution of the material grain
size and the surface hardness when varying the cutting speeds (180 - 720 m/min) and tool nose radii (0.4 - 1.2 mm). All
simulations were performed for dry cutting conditions using uncoated carbide tools. The effectiveness of the proposed FE
model was demonstrated through its capability to predict grain size evolution and hardness modification from the bulk
material to machined surface. The model is validated by comparing the predicted results with those experimentally observed