Correlation between pulse frequencies, microstructure and mechanical properties of TA15 in wire and arc additive manufacturing

Wire and arc additive manufacturing (WAAM) has been developed to be a highly efficient technique for making large Ti-alloy products. However, the deposition of metal by this method causes coarse texture, which limits its application. To address this, the study utilizes a wire and pulsed arc additive manufacturing (WPAAM) process for making TA15 alloy. Compared with the WAAM method, this WPAAM method inducts several current/voltage-impulse cycles under different pulse frequencies, which makes grains tiny and improves tensile strength. The study then uses a VOF model to discuss the effect of impulse cycles on the solidification process. The findings suggested that the impulse cycles deform the molten pool and influence the vibration in the solid/liquid interface. This makes the coarse columnar grains tiny and forms diminutive α laths. This paper further discusses the correlation between the microstructure and the mechanical properties. The results show that the CBGs and the α laths play a joint contribution to yield strength in the WAAMed TA15 alloy. This study provides a reference for optimizing the microstructure of WAAM titanium alloys by adjusting pulse frequencies and provides a theoretical basis for strengthening WAAMed Ti-alloy.