Surface modification of hydroturbine steel using friction stir processing

► Friction stir processing (FSP) of CA6NM steel was successfully attempted. ► Microstructure of the steel was refined with 10 folds reduction in grain size. ► EBSD results confirmed variable texture across the stir zone. ► FSPed CA6NM steel showed 2.6 times improvement in hardness. ► Cavitation erosion resistance of steel was enhanced by 2.4 times after FSP.