The aim of this work was to study the deformation behavior of an Armco iron after severe plastic deformation by equal channel angular pressing (ECAP). Particular attention was paid to predict the dislocation density by different approaches like the model proposed by Bergström. Experimental measures of dislocation density by different techniques are used in the discussion. Cylindrical samples of ARMCO iron (8mm of diameter, 60mm of length) were subjected to ECAP deformation using a die with an intersecting channel of Φ=90° and outer arc of curvature of ψ= 37° die. Samples were deformed for up to 16 ECAP passes following route Bc. The mechanical properties of the material were measured after each pass by tensile tests. The original grain size of the annealed iron (70 μm) was drastically reduced after ECAP reaching grain sizes close to 300nm after 16 passes.

Using Finite Element Method (FEM) simulations is possible to study the homogeneity of deformation in the Equal Channel Angular Pressing (ECAP) process. In this work an investigation about the influence of a modified die on strain distribution in an ecaped Al6060 alloy was carried out. Due to that, tensile stress occurs in the vicinity of upper surface of the specimen in the severe plastic deformation zone, which increases the cracking and fracture tendency of the specimen and impedes further ECAP processing, the conventional ECAP die was modified to eliminate the tensile stress and enhance the compressive stress in the severe plastic deformation zone and reducing the cracking and fracture tendency of the specimen. Finite element analysis demonstrated that the stress state changes from tensile to strongly compressive when using the modified die. The aim of this study is to evaluate the advantages/disadvantages of the modified ECAP die and processing conditions.

High-pressure torsion (HPT) is a processing technique in which samples are subjected to a high pressure and torsional straining. Anvil alignment and anvil roughness are two important factors related to the successful application of the HPT processing technique. Using a two-phase duplex stainless steel as a model material, experiments were conducted by placing the anvils in different amounts of initial misalignment. Experiments show that the flow patterns (the development of double-swirl patterns) in HPT are dependent upon the alignment of the anvils within the HPT facility. Through carefully designed experiments, it is shown that the presence of a double-swirl is a feature of HPT processing when the initial positions of the anvils have a small lateral misalignment. The effect of the double-swirl patterns on the hardness evolution was also evaluated quantitatively. By comparing the flow patterns developed on the disc upper surface using both rough and smooth anvils with a fixed anvil misalignment, it was demonstrated that there are some differences in the flow patterns which are dependent upon the anvil surface roughness.

Equal channel angular pressing (ECAP) was carried out on extruded ZK60 magnesium alloy until an equivalent strain of ∼4 (corresponding to 4 passes) at 523K following route Bc. The effect of the deformation on both microstructure and texture was investigated by analysis of inverse pole figures and pole figures respectively, determined by EBSD. Additionaly, the mechanical properties were evaluated through tensile tests. The ECAPed processed ZK60 alloy showed the presence of dynamic recrystallization (DRX) process, correlated with a strong basal fiber texture. The presence of pyramidal slip was also observed, which can be correlated with the presence on twin-oriented boundaries in the material. Both the grain size reduction and the existence of texture influenced the ductility of the magnesium alloy processed by ECAP, as the ductility of the ZK60 alloy after four ECAP passes increased two times in comparation with the initial (un-processed) material.