Laser welding with powder feed

Laser welding with a powder feed has been investigated using a 3·0 kW CO2 laser system. This type of welding is a modification of autogenous laser welding. In the present investigation, a straight thin tube nozzle was used to deliver powder to the welding area by a computerised powder feeder. The delivered powder is melted and mixed by interaction with the laser beam to form a weld with the base metal. This technique can extend the capabilities of autogenous laser welding while retaining many of its advantages. A series of welding parameters was used to produce butt joints with a satisfactory weld bead profile at various joint gap sizes. The main objective of the present study was to use a power feed to accommodate joint gaps which often present problems in autogenous laser welding. Promising results have been obtained. A joint gap of up to 1·0 mm has been welded successfully in 3·0 mm thickness steel: a great improvement compared with autogenous laser welding. In the present study, weld microstructure, composition, hardness, and tensile properties were investigated. The investigation indicated that the joints possess sufficient strength. The practical implication of the results is that tight fitup requirements for laser welding can be relaxed somewhat for many demanding industrial applications. Although further development is still required to optimise the technique, its potential has been demonstrated.