I have the grain size values after friction stir processing, but I would like to estimate the tensile strength (yield or UTS) using Hall-Petch equation., the tensile testing machine is down for a while so I would like to predict if there an increase in tensile after FSP, Also most of the literature suggests grain boundary strengthening promotes for increase in strength after FSP, but I would like to consider other strengthening mechanism involved like solid-solution strengthening, precipitation strengthening & strain hardening effect in the steel after FSP process. I would like to compare all these strengthening mechanism and analyze the most strengthening mechanism. Also for hall-Petch equation how do I get the constants for the equation especially for A572 grade 50 steel.