Influence of Processing Route on the Fracture Resistance of Equal Channel Angular Pressing Deformed Iron

The mechanical behavior of pure iron (Armco-iron) deformed at 200 °C by equal angular channel pressing using processing route BC is investigated with a focus on the fracture properties. In particular, the fracture toughness in terms of elastic–plastic fracture mechanics is evaluated for different specimen orientations with respect to the last deformation step. In addition, the results are comprehensively compared with material processed by route A. The microstructural features of both deformation routes are presented and the underlying microstructure–property relationships are discussed. Both deformation routes (A and BC) lead to a comparable strength even though the microstructural features differ. Route A contains a banded and well-aligned structure almost parallel to the extrusion direction. For route BC, the microstructural alignment is rotated with respect to the pre-crack orientation and the grain structure is more heterogeneous. For both deformation routes, the crack plane orientation plays a significant role in the fracture characteristics. The fracture toughness along the extrusion direction, with substantially low fracture toughness for route A, is markedly enhanced for route BC. Consequently, route BC offers a pathway to obtaining severe plastic deformation (SPD) materials with high damage tolerance and a considerably lower extent of anisotropy.