The role of curvature of the crystal structure in the formation of micropores and crack development under fatigue fracture of commercial titanium

The multiscale mechanism of fatigue fracture of titanium with the surface layer hydrogenated under alternating bending at room temperature is studied. It is shown that the generation of the fatigue fracture occurs in the surface layer subjected to plastic deformation in conjunction with an elastically loaded substrate. The latter causes the appearance of a strong curvature of the material and the appearance of micropores in these areas along with any fatigue cracks. The emergence of the local curvature of the crystal structure plays a central role in the origin and the development of the fatigue fracture as the structural phase decomposition of the material under cyclic loading.