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SEMINAR: Challenges and Consequences of Uncertainties in Metal Laser Powder Bed Fusion
March 21, 2018 @ 10:00 am - 11:00 am
Additive manufacturing (AM) offers unprecedented opportunities to design complex geometries and optimized topologies for performance gains inaccessible under conventional manufacturing constraints. However, to facilitate adoption in high consequence applications, fundamental questions regarding the intrinsic reliability and repeatable performance of additive metals must be answered. Distinct from traditional subtractive processes, component geometry and material are formed concurrently in additive processes and preclude an a priori knowledge of material performance from feedstock properties. Of interest are powder bed fusion processes where a laser scans across successive layers of metal powder to fuse material and generate a desired part geometry. Such layerwise processing enables access to volume elements, i.e. voxels, throughout every part with opportunities for material control but also defect formation.
Predicting material performance is challenging for powder bed processes since it involves complex melting and solidification interactions, and is implemented on equipment with limited capabilities for process control and/or defect tracking. Consequently, material performance is commonly indeterminate and introduces unacceptable uncertainties for certifying and qualifying additive components. On-going research is working to reduce these uncertainties by exploring the process-structure-properties triad of stainless steel alloys. Material characterization and testing is identifying the nature of critical defects, quantifying their impact on material properties, correlating their presence with processing conditions, and developing a basis for understanding defect formation mechanisms. Thus, critical defect “signatures” will be presented to provide a predictive framework for quantifying material performance distributions using techniques that span in-situ process monitoring, post-process computed tomography, metallography and tensile testing.
Dr. Bradley H. Jared is a Principal Member of the Technical Staff at Sandia National Laboratories where he leads research and development efforts in precision engineering and advanced manufacturing within the Materials Science and Engineering Center. His Sandia research has spanned applications in optics, photonics, micro-photovoltaics, satellites and weapon systems as he has led efforts in meso-machining, diamond turning, micro-metrology, ultrafast pulsed laser processing and additive manufacturing. He received a B.S. in mechanical engineering from the University of Tennessee-Knoxville, and M.S. and Ph.D. degrees in mechanical engineering from North Carolina State University. He spent almost a decade in industry prior to joining Sandia performing research in precision fabrication, design and assembly to support photonic and life science products at Corning and consumer display products at 3M. He has performed, presented and/or published work in the fields of ultra-precision diamond turning, micro-machining, ultrafast pulsed laser processing and additive manufacturing.