Fiber laser hybrid welding of stainless steels

Laser welding gives better penetration than conventional welding methods and can significantly increase the welding speed. Use of laser hybrid welding can further enhance the welding speed by improving gap bridgeability and allowing the addition of filler metal to facilitate welding of special grades. Fiber laser gas-metal arc (GMA) hybrid welding was performed on 8 mm austenitic 316L (EN 1.4404/1.4432, UNS S316L) and duplex 2205 (EN 1.4462, UNS S31805) stainless steel with the recommended filler wires. Both leading and trailing laser positions were applied. The differences between these configurations are discussed in terms of weldability, resulting microstructure and the influence on ductility. Trailing laser proved to be the only reliable option for achieving high quality welds, although at a somewhat reduced welding speed if compared to leading laser. Radiographic non-destructive testing was unsuitable for detecting small, but detrimental, weld defects such as hot cracks and lack of fusion found in the weld cross-sections when leading laser position was used.