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Extreme-Value Statistics Reveal Rare Failure-Critical Defects in Additive Manufacturing

Advanced Engineering Materials

Boyce, Brad B.; Salzbrenner, Bradley S.; Rodelas, Jeffrey R.; Swiler, Laura P.; Madison, Jonathan D.; Jared, Bradley H.; Shen, Yu L.

Additive manufacturing enables the rapid, cost effective production of customized structural components. To fully capitalize on the agility of additive manufacturing, it is necessary to develop complementary high-throughput materials evaluation techniques. In this study, over 1000 nominally identical tensile tests are used to explore the effect of process variability on the mechanical property distributions of a precipitation hardened stainless steel produced by a laser powder bed fusion process, also known as direct metal laser sintering or selective laser melting. With this large dataset, rare defects are revealed that affect only ≈2% of the population, stemming from a single build lot of material. The rare defects cause a substantial loss in ductility and are associated with an interconnected network of porosity. The adoption of streamlined test methods will be paramount to diagnosing and mitigating such dangerous anomalies in future structural components.

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TYPE Journal Article YEAR 2017
ScopusOSTIDOI

Simulation of metal additive manufacturing microstructures using kinetic Monte Carlo

Computational Materials Science

Rodgers, Theron R.; Madison, Jonathan D.; Tikare, Veena T.

Additive manufacturing (AM) is of tremendous interest given its ability to realize complex, non-traditional geometries in engineered structural materials. However, microstructures generated from AM processes can be equally, if not more, complex than their conventionally processed counterparts. While some microstructural features observed in AM may also occur in more traditional solidification processes, the introduction of spatially and temporally mobile heat sources can result in significant microstructural heterogeneity. While grain size and shape in metal AM structures are understood to be highly dependent on both local and global temperature profiles, the exact form of this relation is not well understood. Here, an idealized molten zone and temperature-dependent grain boundary mobility are implemented in a kinetic Monte Carlo model to predict three-dimensional grain structure in additively manufactured metals. To demonstrate the flexibility of the model, synthetic microstructures are generated under conditions mimicking relatively diverse experimental results present in the literature. Simulated microstructures are then qualitatively and quantitatively compared to their experimental complements and are shown to be in good agreement.

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TYPE Journal Article YEAR 2017
ScopusOSTIDOI
Results 51–75 of 156
Results 51–75 of 156