Microstructural characterisation and mechanical evaluation of Ti-15Mo manufactured by laser metal deposition
Edohamen Awannegbe, Huijun Li, Tingting Song, Frank Nießen, Ma Qian, Azdiar A. Gazder, Mitchel J. B. Nancarrow, Elena V. Pereloma
Abstract
A bidirectional powder deposition strategy was employed to additively manufacture Ti-15Mo wt% using laser metal deposition. Phase identification, elemental analysis and microstructural characterisation were conducted after fabrication and uniaxial tensile testing using X-ray diffraction and scanning electron microscopy along the different processing directions. In addition, electron backscattering diffraction and transmission electron microscopy were used to analyse deformation mechanisms. It was found that three distinct zones, namely the fusion, remelted and heat affected zones, evolved in all 25 deposited layers which predominantly comprised coarse columnar grains. Mo segregation was pronounced in the as-built microstructure. Deformation accommodation in β matrix was by a combination of slip, {332}<113> and {112}<111> twinning, and α′′ martensite and ωD formation contrarily to the expected twinning.