Friction stir processing as a strengthening technique for medium carbon low alloy steels

Friction stir processing (FSP) has shown its potential in the controlled microstructure evolution in steels. It is fact that the microstructure i.e. grain size, crystal orientation, type of phase and phase fraction, plays the most important role in the determination of mechanical properties. In this work, material gets strengthened by 1.5 times yield strength, 1.41 times ultimate strength as compared to base material after FSP. Ductility was observed to be decreased to 23% as compared to 32.5% of base material. The hardness of processed zone was observed to be 1.5 times that of the base material. The changes in the properties are studied in the context of microstructure resulted from the severe plastic deformation and thermomechanical effect of friction stir processing. The stir zone (SZ)/processed zone (PZ) is observed to have dual-phase structure, retained austenite along with nanosized carbide particles. © 2022