Nondestructive investigation on close and open porosity of additively manufactured parts using an X-ray computed tomography

Abstract

Additive manufacturing (AM) has been gradually adopted by different industrial sectors including aerospace, automotive and medical industries etc. The layer by layer AM process has its unique advantage to fabricate complex parts using a computer aided design. Selective laser melting (SLM) and binder jet printing (BJP) are two important methods in AM family. SLM and BJP introduce closed pores affecting AM parts’ mechanical property and open pores affecting gas purification while AM part as a filter, respectively. It is important to quantify those internal pores to optimize AM process parameters’ setting. In this paper, a close porosity (CP) of AM parts by SLM with remelting process and different printing parameters (laser power and scanning speed) and an open porosity (OP) of AM parts by BJP have been characterized. X-ray computed tomography (XCT) has been successfully employed to inspect CP and OP related to either closed pores or open pores in AM parts accordingly. It is found that: 1) For given parts by SLM, the CP values can be varied in a range from 0.07% to 0.34%, subjected to different printing parameters’ setting and 2) For given parts by BJP, the OP value can be controlled over 50% for gas purification. It demonstrated that XCT is capable of conducting non-destructive quality testing and related printing parameters optimization in metallic AM.