Nanostructurization assisted by twinning during equal channel angular pressing of metastable 316L stainless steel

A conventional SUS 316L low carbon stainless steel has been processed by Equal channel angular pressing (ECAP) to the equivalent shear strain equal to 2, 4, 6 or 8 at different temperatures ranging from 250 °C to room temperature. The aim of this study is to gain extra control over the “strength-ductility” combination via nanostructure formation, involving twinning and/or strain-induced phase transformation. The resultant microstructure is examined by transmission electron microscopy, X-ray diffraction and electron back scattered diffraction (EBSD) techniques. Substantial structure refinement down to nanoscale is observed in parallel with significant enhancement of tensile yield and ultimate tensile stress, both exceeding 1GPa. A considerable resistance to fracture during localized plastic flow and a fairly good elongation to fracture in tension is reported.