Oblique laser irradiation technique for vertical welding of thick steel plates employing hot-wire laser welding

The present study investigates laser irradiating and hot-wire feeding methods, specifically vertical laser irradiation with double hot-wire feeding and oblique laser irradiation with single hot-wire feeding. The effect of the laser irradiating angle was obtained by making cross-sectional observations of a joint with a 10-mm gap. Oblique laser irradiation with single hot-wire feeding was then applied to a relatively small gap (5 mm) to investigate the gap tolerance of the method. A laser diode with a large rectangular beam spot and hot-wire system were employed in the proposed process. Results showed that while oblique laser irradiation at an angle of 15° achieved almost the same weld bead as vertical laser irradiation (0°), the larger laser irradiating angle of 30° resulted in extremely large imperfection and a small amount of base metal melting. Oblique laser irradiation and single hot-wire feeding could be used practically, and their combination with laser weaving could allow large gap tolerance.