Metal 3D printing has garnered a lot of attention over the last 5 years. The basic technology, however, is more than 30 years old . Some argue that the expiration of original patents is the reason behind the current surge of attention and start-up companies . So, more than 30 years later, is it possible to regularly print metal parts?
In the first part of this presentation I will discuss the answer to this question by highlighting some current engineering challenges and basic material behavior questions that arise in this context. I will then focus my attention on our efforts to address some of them, namely, understanding and controlling Selective Laser Melting (SLM). In this process, two-dimensional slices of a part are "built" by a laser over successively stacked layers of metal powder to form a three-dimensional object. In particular, I will describe: (a) our combined experimental and modeling approach towards understanding the temperature history of metal particles (SS 17-4 PH) in the neighborhood of a region melted by the laser beam and its effect on the resulting microstructure, and (b) a recent study we performed to monitor the evolution of the melt pool induced by the laser beam with ultrasound in real time .
Parts of this talk are joint work with Wei Cai (Stanford), Yi Shu (Stanford), Daniel Galles (Army Research Laboratories), Brandon McWilliams (Army Research Laboratories), and Nancy Yang (Sandia National Laboratories).
 Flynt, Joseph. "A Detailed History of 3D Printing," https://3dinsider.com/3d-printing-history/
 Filemon, Joseph. "How expiring patents are ushering in the next generation of 3D printing," https://techcrunch.com/2016/05/15/how-expiring-patents-are-ushering-in-t...
 Kube, C. M., Shu, Y., Lew, A. J., & Galles, D. (2018). Real-Time Characterization of Laser-Generated Melt Pools using Ultrasound. Materials Evaluation, 76(4), 525-534.