Topographic Measurement of Individual Laser Tracks in Alloy 625 Bare Plates

Additive manufacturing (AM) combines all of the complexities of materials processing and manufacturing into a single process. The digital revolution made this combination possible, but the commercial viability of these technologies for critical parts may depend on digital process simulations to guide process development, product design, and part qualification. For laser powder bed fusion (LPBF), one must be able to model the behavior of a melt pool produced by a laser moving at a constant velocity over a smooth bare metal surface before taking on the additional complexities of this process. To provide data on this behavior for model evaluations, samples of a single-phase nickel-based alloy were polished smooth and exposed to a laser beam at 3 different power and speed settings in the National Institute of Standards and Technology (NIST) Additive Manufacturing Metrology Testbed (AMMT) and a commercial AM machine. The solidified track remaining in the metal surface after the passing of the laser is a physical record of the position of the air-liquid-solid interface of the melt pool trailing behind the laser. The surface topography of these tracks was measured and quantified using confocal laser scanning microscopy (CLSM) for use as benchmarks in AM model development and validation. These measurements are part of the Additive Manufacturing Benchmark Test Series (AM-Bench).