Effect of electroshocking treatment on the microstructure and mechanical properties of laser melting deposited near-β Ti-55531 thin-wall.

The near-β Ti-55531 (Ti-5Al-5Mo-5V-3Cr-1Zr, wt%) alloy with thin-wall structures were manufactured by laser melting deposition (LMD), and followed by the post-processing of electroshocking treatment (EST). The microstructure evolution before and after EST were characterized via using the scanning electron microscopy (SEM), electron backscatter diffraction (EBSD) and X-ray diffraction (XRD). The results showed that the microstructure of as-deposited specimen was mainly composed of short columnar grains and equiaxed grains, showing a unique structure of alternating short columnar grains-equiaxed grains-short columnar grains. The results of EBSD showed that EST could reduce the orientation concentration and weaken the texture of β phase. XRD results indicated that the α phase content slightly increased after EST. The micro-strain and lattice constant of β phase were changed after EST, which were probably ascribed to the precipitation of α, the generation of crystal defects on α/β interface, and the decrease of texture intensity. The results of mechanical properties indicated that EST could increase the microhardness, the yield strength and the tensile strength, which were due to the variation of microstructure. All results show that EST is an effective approach for optimizing the microstructure and improving the mechanical properties of LMD near-β titanium alloy. [Display omitted] • LMD Ti-55531 shows a unique structure of alternating columnar-equiaxed-columnar grains. • EST can alleviate the orientation concentration and weaken the texture of β phase. • More α tends to precipitate inside β after EST, due to the thermal and athermal effects of EST. • Variation of micro-strain and lattice constant are ascribed to the precipitation of α and decrease of texture intensity. • EST can optimize microstructure and improve mechanical properties of LMD near-β titanium alloy. [ABSTRACT FROM AUTHOR]