A cyclic tension and alternating bending tests of 12Cr1MoV steel specimens in as-supplied state and after surface nanostructuring by Zr+ ion beam have been carried out. Distinctions in formation of strain induced relief, as well as the cracking pattern of modified surface layer are illustrated by methods of optical microscopy and interferential profilometry. Changes to occur in subsurface layer are characterized by means of nanoindentation and fractography observation of fracture surfaces. The description of differences of deformation behavior is performed with use of the multiple cracking concept.