Melting by Reflected Laser Beam during Vertical Welding via Hot-Wire Laser Welding

Abstract

We investigated the melting of a base metal, molten pool growth, and joint creation during vertical welding via hot-wire-laser welding. Three laser-weaving conditions were investigated by changing the weaving frequency and waveform to study the effects of the irradiation duration near the groove surface. In addition, high-speed and cross-sectional imaging were performed to investigate the heating and melting processes on the groove surface during hot-wire laser welding. The irradiation duration near the groove surface in a cycle had a marked effect on the melting of the groove surface. The combination of a 5Hz laser frequency with an exponential waveform led to a longer duration near the groove surface during a cycle and realized improved fusion compared with the other combinations with a 15Hz laser frequency and a sine waveform. The laser beam reflected from the molten pool surface was the main source of heat for melting the groove surface. Hot-wire feeding provided a continuous and efficient supply of melted material and a stable heat input on the groove surface via the reflected laser beam.