The Impact of Residual Stresses and Porosity on the Performance of Laser Metal Additive Manufactured (MAM) Components: A Review

Rapid heating, cooling rates, and melt-back-the simultaneous melting of the top material layer and the remelting of underlying, previously hardened layers-are characteristics of the special thermal cycle of metal AM. This particular thermal cycle in metal AM results in strong residual stress gradients, which pose a major problem for the created components. Because residual stresses cause part deformations and/or microcracks, they severely restrict the practical usage of the parts that are produced. Furthermore, compared to a stress-free state, significant residual strains may restrict the parts' ability to withstand loads. Every production process introduces some residual tension. Nonetheless, various production methods introduce significant differences in the amount of residual stress. Because laser-based techniques naturally include substantial heat gradients, it is known that these methods can produce significant residual stress.