Research on Relationship between Microstructures and Mechanical Properties of TA15 Bars

Lamellar and equiaxed microstructures of TA15 bar were characterized by BEI and EBSD techniques,focusing on the alloying elements distributions and their effects on the corresponding mechanical properties.Image Quality（IQ）and chemical composition analysis indicate that 20% of alloying elements in solid solution of β phase produce remarkable lattice distortion and consequent higher solid solution strengthening than α phase.The contribution of solid solution strengthening is greater than that of grain refinement strengthening,resulting in a similar yielding strength of these two microstructures.The equixed microstructure with finer grains,uniform distribution of β phase and about 29% of low angle grain boundaries（LAGB）,exhibits homogeneous deformation and then raises the tensile strength and plasticity,making comprehensive mechanical properties better than those of the lamellar structure.