In the present work model materials (pure iron, pure nickel) and technically used rail steels are deformed by methods of high pressure torsion to well defined shear strains. Both monotonic and cyclic methods are used. With this samples, the evolution of the microstructure as well as the changes in the mechanical properties as a function of the predeformation is studied. It can be seen that in pure metals, a distinctive grain refinement occurs. The structure size after strains approximately larger than 2000 per cent is markedly smaller than 500 nm, the tensile strength increases up to 1500 MPa (iron). In steels, the deformation is dominated by the carbides. The carbides are severely deformed, fragmented, aligned parallel to the shear plane and may even dissolve. This alignment of the microstructure leads to a strong anisotropy in the mechanical properties. To characterize this anisotropy, tensile strength, fracture toughness and fatigue crack propagation were determined for different orientations.