MSE Faculty Candidate Seminar: “Defect Structure Process Maps for Laser Powder Bed Fusion Additive Manufacturing”

Additive manufacturing (AM) greatly expands the design freedom and near-net shape production of metallic components across multiple length scales. However, defects arising from starting materials, processing conditions, and post-processing may significantly affect the structural integrity and operational performance of metal AM parts. This paper seeks to elucidate common defects and defect formation mechanisms encountered in typical laser powder bed fusion (LPBF) AM processes. While the defect structures of conventional joining processes such as laser welding have been studied extensively, this talk primarily focuses on the nature of porosity transfer to the finished part exclusively for metal AM powder bed processing techniques. Multiple starting powders and analysis methods are summarized which demonstrate that the manifestation of defects within metal AM builds largely stems from the particular choice of process settings, with some influence of powder feedstock choice and post-processing heat treatments. Practical build strategies to limit the occurrence of defects by the use of process mapping and geometric modeling are also evaluated utilizing this fundamental understanding of defect formation. Such explorations may enable the validation and calibration of models to permit process qualification without the reliance on costly trial and error type experimentation currently employed.