“…In this approach, understanding of the significance of rotational modes of deformation appeared to be of crucial importance. [12][13][14][15][16][17][18] The 17Mn1Si (X70 grade) structural steel (%0.2C, %0.5Si, %1.7 Mn À all in wt%) has long been successfully used due to a good combination of high strength, ductility, and fracture toughness. Its mechanical properties (ultimate tensile stress s % 570 MPa, elongation at break d % 20% and fracture toughness KCV % 150 Jcm À2 ) have been comprehensively documented for smooth specimens.…”