Product Code: ICAL05_P554

Effects of Hybrid Welding Parameters on Porosity Formation in C-Mn Steel for Shipbuilding
Authors:
Seung-Gab Hong, Posco; Pohang Korea
Jong-Bong Lee, Posco; Pohang Korea
Presented at ICALEO 2005

The effects of hybrid welding parameters on porosity formation in fillet joint have been investigated by using primer-coated AH36 steel. X-ray transmission images revealed that most of porosities in fillet joint were observed near back bead and the shapes of these porosities were similar to blow holes. From elemental mappings using EPMA near porosities, we could presume that the porosity formation was not attributed to Zn metal, which was contained within primer. From the investigation on correlation between hybrid welding parameters and area ratio of porosities, we found that both decrease of wire feed rate and increase of separation between laser beam and arc dramatically decreased the area ratio of porosities near back bead of fillet joint. Therefore, it is believed that the porosity formation near back bead was attributed to keyhole instability, which was caused by increase of influent molten metal into weld pool.