Scanning strategies effect on temperature, residual stress and deformation by multi-laser beam powder bed fusion manufacturing

Laser beam Powder Bed Fusion (PBF-LB) is an increasingly attractive technology due to its capability of manufacturing complex and customised metal parts. However, the build cycle time and resulting residual stress profiles are limiting a wider uptake of PBF-LB manufacturing. The incorporation of additional laser beams in a single build chamber, i.e. multi-laser beam Powder Bed Fusion (PBF-MLB) technology, has been proposed as the next generation of PBF-LB technology. A series of computational process simulations of PBF-MLB was carried out using a 3D coupled thermomechanical model to investigate optimum multi-laser scanning strategies. The influences of twelve different scanning strategies on temperature, the final residual stresses, the z- (build) direction deflections by dual Gaussian profile laser beams PBF-MLB were investigated. It was found that the 90° layer rotation is necessary to reduce the residual stress, and a ‘dual-laser following but time-delayed’ scanning strategy had the lowest final residual stress. Another scanning strategy (45° rotation approaching beam scanning) resulted in the lowest z-direction deflection for the dual laser beams PBF-MLB manufacturing. These findings provide insight and application of PBF-MLB finite element process simulation in improving industrial additive manufacturing of metal components.