Analytical modeling of work hardening of duplex steel alloys in the milling process

Severe plastic deformation in cutting operations such as milling might change mechanical properties (especially the strength and hardness) of the machined surface and its underlying layers. This phenomenon called work hardening and reduces machinability. This study presents an analytical solution to calculate the work hardening of the upper layers of the workpiece in the milling process of 2205 duplex stainless steel. In this regard, the stresses in the cutting regions are calculated to find the stress and temperature fields in the workpiece. Then the strain and strain rate values are calculated for each point of the surface and subsurface layers using the determined stress field. Finally, the Johnson-Cook material model is used to calculate flow stress and work hardening. Experimental results of the different machining conditions have been used to validate the proposed model. However, comparisons of subsurface microhardness and resultant cutting force obtained by an analytical model with experimental tests showed that the model properly predicts the amount of work hardening.