Effect of electropulsing on anisotropy in strength of laser metal deposited Ti-6Al-4V alloy
(1. Institute of Materials Processing and Intelligent Manufacturing, College of Materials Science and Chemical Engineering, Harbin Engineering University, Harbin 150001, China;
2. Key Laboratory of Superlight Materials and Surface Technology, Ministry of Education, College of Material Science and Chemical Engineering, Harbin Engineering University, Harbin 150001, China)
2. Key Laboratory of Superlight Materials and Surface Technology, Ministry of Education, College of Material Science and Chemical Engineering, Harbin Engineering University, Harbin 150001, China)
Abstract: The effect of electropulsing treatment on microstructure and mechanical strength of laser metal deposited Ti-6Al-4V alloy was investigated in order to eliminate the anisotropy in strength of laser metal deposited Ti-6Al-4V alloy by tensile tests, optical microscopy, scanning electron microscopy, electron back-scattered diffraction analyses and transmission electron microscopy. With increasing applied voltages from 0 to 130 V, the evolution of microstructure within columnar β grains followed the sequence of α′ martensite → colony α structure → basket-weave α structure. The electropulsing treated at 130 V weakened the texture of martensite within β grains. The as-built Ti-6Al-4V alloy showed an anisotropy in yield strength (6.2%). After processing at 130 V, the anisotropy in yield strength was reduced to 0.6%, which was attributed to the almost equivalent distribution of Schmid factor in the samples deformed along different orientations.
Key words: laser metal deposition; Ti-6Al-4V alloy; yield strength; anisotropy; electropulsing