Showing papers by "Tarasankar Debroy published in 2017"
TL;DR: In this article, a well-tested, three-dimensional, transient heat transfer and fluid flow model is used to accurately calculate transient temperature field for the residual stress and distortion modeling.
494 citations
TL;DR: In this article, a digital twin of the laser-based directed energy deposition additive manufacturing (DED) process is proposed to provide accurate predictions of the spatial and temporal variations of metallurgical parameters that affect the structure and properties of components.
252 citations
TL;DR: In this paper, the main building blocks of a first generation digital twin of additively manufactured (AM) components are presented from the viewpoints of researchers from several organizations, and a perspective of the current status and research needs are provided.
178 citations
TL;DR: In this paper, the authors developed a roadmap to mitigate distortion during additive manufacturing using a strain parameter and a well-tested, three-dimensional, numerical heat transfer and fluid flow model.
146 citations
TL;DR: In this paper, the evolution of grain structure and topology in three dimensions in both the FZ and the HAZ considering the motion of the liquid pool was investigated. And the results showed that the grain size distributions and topological class distributions were largely unaffected by the temporal and spatial variations of the temperature created by different welding parameters.
126 citations
TL;DR: In this article, the effects of many process variables and alloy properties on the structure and properties of additively manufactured parts using four dimensionless numbers were examined using a well-tested three-dimensional transient heat transfer and fluid flow model.
Abstract: The effects of many process variables and alloy properties on the structure and properties of additively manufactured parts are examined using four dimensionless numbers. The structure and properties of components made from 316 Stainless steel, Ti-6Al-4V, and Inconel 718 powders for various dimensionless heat inputs, Peclet numbers, Marangoni numbers, and Fourier numbers are studied. Temperature fields, cooling rates, solidification parameters, lack of fusion defects, and thermal strains are examined using a well-tested three-dimensional transient heat transfer and fluid flow model. The results show that lack of fusion defects in the fabricated parts can be minimized by strengthening interlayer bonding using high values of dimensionless heat input. The formation of harmful intermetallics such as laves phases in Inconel 718 can be suppressed using low heat input that results in a small molten pool, a steep temperature gradient, and a fast cooling rate. Improved interlayer bonding can be achieved at high Ma...
112 citations
TL;DR: In this article, the effects of welding speed on the dimension, distribution, orientation, and morphology of columnar and equiaxed grains were studied for keyhole mode laser welding of copper.
82 citations
TL;DR: In this paper, the microstructures of both single and double pulsed gas metal arc welding are presented to demonstrate significant microstructural refinement for the same heat input, and the temporal variations of cooling rates, solidification growth rate and weld geometry are examined.
44 citations
Journal Article•
5 citations
31 Dec 2017
TL;DR: In this article, the authors used additive manufacturing (AM) technologies as a highly controllable means for reducing carbon migration through theoretically designed, compositionally graded transition joints guided by appropriate thermodynamic, kinetic and heat transfer and fluid flow modeling.
Abstract: Dissimilar metal joints between ferritic steels and nickel base alloys are currently fabricated using conventional arc welding processes with selected filler metal combinations. The dissimilar metal joints contain abrupt changes in composition over a relatively small distance. Many years of service at elevated temperatures has shown that these welds are susceptible to creep and creep fatigue failures. The primary mechanism for these creep failures involves carbon diffusion from the ferritic steel to the nickel base alloy. As a result, a carbon depleted zone is created that contains very few stable carbides. This work used additive manufacturing (AM) technologies as a highly controllable means for reducing carbon migration through theoreticallydesigned, compositionally graded transition joints guided by appropriate thermodynamic, kinetic and heat transfer and fluid flow modeling. The contents of the report include the objectives and tasks set forth by the PI and collaborators, major technical accomplishments throughout the research and additional details in the form of technical publications resulting from the NEUP grant and reports from the collaborating university and national laboratory.
1 citations