Strength characteristics and fracture of ultrafine-grained titanium Grade 4 processed by equal channel angular pressing–conform

Processing of metals and alloys by severe plastic deformation (SPD) is accompanied by refinement of the material grain structure, which can increase their physicomechanical properties, for instance, unique tensile strength. However, studies of mechanical properties of materials after SPD are usually limited by tensile tests and other properties of strength and fracture are not sufficiently considered. This article presents experimental studies of ultimate tensile strength, impact toughness, fracture toughness, as well as respective surfaces of fracture of initial and ultrafine-grained pure Grade 4 titanium fabricated by continuous equal channel angular pressing. The results demonstrated that upon high ultimate tensile strength after SPD the material demonstrates decreased resistance against initiation and propagation of cracks upon single loading. The fracture surface of both states of titanium structure reveals mainly localized plastic deformation.