Scanning optical microscopy for porosity quantification of additively manufactured components

Electron beam melting (EBM) is a representative powder-bed fusion additive manufacturing technology, which is suitable for producing near-net-shape metallic components with complex geometries and near-full densities. However, various types of pores are usually present in the additively manufactured components. These pores may affect mechanical properties, particularly the fatigue properties. Therefore, inspection of size, quantity and distribution of pores is critical for the process control and assessment of additively manufactured components. Here, we propose a method to quantify the pore size distribution and porosity of additively manufactured components by utilizing scanning optical microscopy. The advantages and limitations of the developed method are discussed based on the comparison study between Archimedes method, conventional optical microscopy and x-ray computed tomography. It is revealed that the new method exhibits the advantages of high precision (similar to 1.75 mu m), more information, high repeatability and low time consumption (20 min/per sample). This provides a new metrology for measurement of not only pores but also micro-cracks, which are the common defects in additively manufactured components.