In-situ investigating the heterogeneous tensile deformation behavior of near β titanium alloys

The tensile deformation mechanism along the forging direction of heat-treated Ti-5Al-5Mo-5V-1Cr-1Fe (Ti55511) forgings characterized by deformed beta grains and <100> beta and <111> beta textures, was investigated via in-situ electron backscattering diffraction (EBSD). At the beta grain scale, strain concentration was prominent in the <100> beta grains compared to <111> beta grains. At the alpha grain scale, mechanical behavior was influenced not only by their crystal orientation but also by surrounding beta grains. In the <100> beta grains region, primary alpha (alpha p) variants favored basal and prismatic slip, and those with well-aligned high-stress slip system experienced significant plastic deformation. Conversely, in the <111> beta grains region, alpha p variants tended towards pyramidal slip, initiating challenging slip transfer to adapt to system deformation. The deterioration in mechanical properties along the forging direction stemmed from uneven deformation in <100> beta grains and non-uniform deformation of alpha p variants within them.