The effect of pulse frequency on the microstructure and properties of TC4 titanium alloy in laser-arc hybrid additive manufacturing

To control the microstructure in the additive manufacturing of titanium alloy, a pulse arc-laser hybrid method was proposed. This study systematically investigates the regulatory mechanism of pulse frequency on the arc behavior, molten pool dynamics, and metallurgical evolution of titanium alloy fabricated via Laser-Arc hybrid additive manufacturing. By comparative analysis of Direct Current (DC) and pulsed arcs at frequencies of 10 Hz, 50 Hz, and 100 Hz, the correlation between electrical parameters and material performance was established. Results demonstrate that a pulsed arc enhances plasma stability and induces molten pool oscillation, which effectively refines grain size and mitigates porosity. Meanwhile, in the sedimentary and overlapping direction, the tensile strengths are 1087.14 MPa and 1071.40 MPa, respectively, representing increases of 15.46% and 8.55% over DC samples. Furthermore, the coefficient of friction and wear rate were reduced by 17.47% and 9.39%, respectively. These improvements are attributed to the formation of a highly refined, uniform martensitic needle and basket-weave microstructure.