The effect of output fibre diameter when welding austenitic stainless steel with a fibre laser

Abstract

Fibre lasers are attractive for use in welding process because of their combination of properties which include high power and a good beam quality. However, the use of fibre lasers as a heat source to join stainless steel has not been extensively investigated. The aims of this research are to establish suitable parameters for fibre laser welding of austenitic stainless steel and to investigate the effect of laser power, welding speed and diameter of the delivery fibre on the weld properties including weld bead shape, dimensions and microstructure. Bead on plate welds were made on grade AISI 304 austenitic stainless steel using a fibre laser with a maximum power output of 2 kW using delivery fibres of diameters 200, 400 and 600 µm. The bead shape and microstructure of steel welds were observed by optical microscopy and the hardness of welds at different process parameters was measured. The results show that the penetration width and depth are related to the welding speed and power density. The weld bead shapes are different with different size of delivery fibres. The penetration depth and width are much deeper and narrower at higher laser power density i.e. when using the smaller diameter delivery fibre.Fibre lasers are attractive for use in welding process because of their combination of properties which include high power and a good beam quality. However, the use of fibre lasers as a heat source to join stainless steel has not been extensively investigated. The aims of this research are to establish suitable parameters for fibre laser welding of austenitic stainless steel and to investigate the effect of laser power, welding speed and diameter of the delivery fibre on the weld properties including weld bead shape, dimensions and microstructure. Bead on plate welds were made on grade AISI 304 austenitic stainless steel using a fibre laser with a maximum power output of 2 kW using delivery fibres of diameters 200, 400 and 600 µm. The bead shape and microstructure of steel welds were observed by optical microscopy and the hardness of welds at different process parameters was measured. The results show that the penetration width and depth are related to the welding speed and power density. The weld bead sh...