Producing nanostructured super-austenitic steels by friction stir processing

► FSP was successfully used to produce nanostructured super-austenitic steel. ► FSP led to breaking down the coarse sigma precipitates into the nanosize ones. ► Determinable effect of sigma can be minimized by its fragmentation to nanoparticles. ► FSP is a unique approach to break coarse particles to attain a uniform microstructure.