Journal ArticleDOI
Microstructure of stainless steel single-crystal electron beam welds
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TLDR
In this article, a 3-D geometrical analysis of weld microstructures and associated dendritic growth patterns is presented based on a three-dimensional (3-D) geometric analysis, including the effects of both the growth crystallography and the weld pool shape.Abstract:
Previously developed techniques by the authors for the microstructural analysis of welds, that included the effects of both the growth crystallography and the weld pool shape, are applied to several cases involving the single-crystal electron beam welding of an Fe-15Ni-15Cr alloy. This evaluation of weld microstructures and associated dendritic growth patterns is based on a three-dimensional (3-D) geometrical analysis. The present study includes examination of the effects observed in overlapping, multipass autogenous welds and butt welds of two single crystals with different orientations, as well as effects due to variations in the welding speed. Weld pool shapes were found to change significantly with increasing welding speed—becoming narrower in cross section but more elongated in the welding direction. Additionally, all electron beam welds showed evidence of a plateau region in the center of the weld pool. The pool shapes, however, were found to be independent of the crystallographic orientation. Therefore, it is possible to extend the pool shape results to crystals welded in any orientation and even to polycrystals. The over-lapping multipass welds showed remarkable reproducibility from pass to pass and duplicated the structural patterns found in single-pass welds. The similarity in dendritic patterns within each pass indicated that the weld pool shapes were identical in all of the passes. The micro-structure of butt welds of two single crystals with different relative orientations showed a remarkable relationship to that associated with each individual crystallographic orientation, and the micro structure was, in effect, simply a composite of two single-pass microstructures. Additional microstructural details were also examined. The tendency toward branching of dendrites was associated with the transition from one dendrite growth orientation to another. It was also found that the nonpenetrating welds exhibited a small protrusion at the bottom of the weld. It is suggested that the modeling of weld pool shapes can be directly evaluated by comparing the predicted dendritic growth patterns based on the modeled shapes with the actual experimentally observed dendritic growth patterns.read more
Citations
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Journal ArticleDOI
Physical processes in fusion welding
Tarasankar Debroy,Stan A David +1 more
TL;DR: In recent years, major advances have taken place in our understanding of welding processes and welded materials because of the complexity of fusion welding processes, solution of many important contemporary problems in fusion welding requires an interdisciplinary approach as mentioned in this paper.
Journal ArticleDOI
Welding: Solidification and microstructure
TL;DR: In this paper, various physical processes that occur due to the interaction of the heat source with the metal during welding add a new dimension to the understanding of the weld pool solidification.
Journal ArticleDOI
Current Issues and Problems in Welding Science
Stan A David,Tarasankar Debroy +1 more
TL;DR: The promise of science-based tailoring of composition, structure, and properties of the weldments may be fulfilled with the development of new methodologies at the crossroad of basic and applied sciences, but this will require resolution of several contemporary issues and problems concerning the structure and properties.
Journal ArticleDOI
Analysis of solidification microstructures in Fe-Ni-Cr single-crystal welds
TL;DR: In this paper, a general procedure for predicting the solidification microstructure of single-crystal welds with any arbitrary orientation is established, and steady state is established within a few millimeters of the beginning of the weld.
Journal ArticleDOI
Localized melt-scan strategy for site specific control of grain size and primary dendrite arm spacing in electron beam additive manufacturing
Narendran Raghavan,Srdjan Simunovic,Ryan R. Dehoff,Alex Plotkowski,John A. Turner,Michael M. Kirka,Suresh Babu +6 more
TL;DR: In this paper, a new melt-scan strategy for inducing site specific, on-demand control of solidification microstructure was developed to induce variations in grain size and primary dendrite arm spacing in Inconel 718 parts produced by the electron beam additive manufacturing system.
References
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Book
Fundamentals of Solidification
W. Kurz,D. J. Fisher +1 more
TL;DR: In this article, Atom Transfer at the Solid/Liquid Interface Morphological Instability of a Solid/ Liquid Interface Solidification Microstructure: Cells and Dendrites SolidificationMicrostructure, Eutectic and Peritectic Solute Redistribution Rapid Solidization Microstructures Summary Appendices Symbols Index
Journal ArticleDOI
Analysis of solidification microstructures in Fe-Ni-Cr single-crystal welds
TL;DR: In this paper, a general procedure for predicting the solidification microstructure of single-crystal welds with any arbitrary orientation is established, and steady state is established within a few millimeters of the beginning of the weld.
Journal ArticleDOI
Development of microstructures in Fe-15Ni-15Cr single crystal electron beam welds
TL;DR: A detailed analysis of the microstructures produced in an autogenously welded single crystal of Fc−15Ni−15Cr was performed in order to investigate the relationship between growth crystallography and solidification behavior as mentioned in this paper.
Journal ArticleDOI
Simulation of oriented dendritic microstructures using the concept of dendritic lattice
M. Rappaz,E. Blank +1 more
TL;DR: In this paper, the distribution of the microstructural heterogeneties is correlated with the crystallographic structure, and the formation of regular dendrite arrangements is explained in terms of crystal growth and branching mechanisms.
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