On Powder Bed Fusion Manufactured Parts: Porosity and its Measurement

Powder Bed Fusion (PBF) is one of the earliest, and most versatile and popular AM processes, being well-suited for a great variety of materials. As in many other manufacturing processes, porosity is a phenomenon inevitably present in parts made by PBF. The quantity, shape, and distribution of pores, and the propensity to their formation depend strongly upon the type of process and on the processing conditions used to produce the part. It is well known that porosity influences in a dramatic way the quality and reliability of the manufactured materials and, therefore, it deserves special attention. In this paper, porosity and the more appropriate experimental techniques for detecting and measuring porosity are reviewed. Moreover, a comparison among the results obtained by applying different methodologies to measure the porosity of parts produced by Powder Bed Fusion is reported. The final purpose of the work is to provide the reader with the tools for the correct choice of the most suitable method for measuring the porosity of additively manufactured pieces.