Material Characterization of Additively Manufactured Metals by Laser Speckle Photometry

In contrast to traditional time-consuming and costly manufacturing processes, additive manufacturing offers an effective production of prototypes. In addition to the numerous process developments of recent years, quality assurance as well as the testing of material properties afterward have now become one of the main requirements. Previous research approaches such as thermography or optical imaging have essential disadvantages, why there is a need for simple and effective solutions. For this purpose, the Laser Speckle Photometry (LSP) as a novel nondestructive approach for evaluating the material quality manufactured by Laser Powder Bed Fusion of Metals (LPBF-M) is presented. For the validation of this testing method exactly defined defective samples were reproducibly fabricated by specific adaptation in the building process. Voids were introduced into the structure, which are not visible on the surface. The simple LSP setup and the adjusted evaluation algorithm, based on the correlation function, are decisive for characterizing different material density states. This paper presents the potential of LSP for the use in LPBF-M processes stated with the first results of the validation.