Tensile Properties of Built and Rebuilt/Repaired Specimens of 316L Stainless Steel Using Directed Energy Deposition
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JMEPEG https://doi.org/10.1007/s11665-020-05087-z
Tensile Properties of Built and Rebuilt/Repaired Specimens of 316L Stainless Steel Using Directed Energy Deposition Louis Simoneau, Alexandre Bois-Brochu, and Carl Blais (Submitted March 11, 2020; in revised form August 6, 2020) One of the most exciting possibilities brought forward by some additive manufacturing (AM) processes is their ability to deposit materials on existing parts. Mainly achievable with directed energy deposition systems, it is thus possible to repair worn or broken components. Two applications were studied in this research: (1) complete construction and (2) repair of tensile specimens made of 316L-Si stainless steel. The latter series was produced by adding material on existing half specimens made of wrought 316L stainless steel. All specimens were built along the Z-axis. Tensile specimens machined from wrought were also tested for comparison purposes. Three conditions were tested for each series of AM specimens: as-built, stress relieved and HIPed. The results show that yield strength, ultimate tensile strength (UTS) and elongation are higher than the typical tensile properties reported for annealed 316L. Repairs show excellent bond resistance with the wrought material and good mechanical properties with a mean UTS of 647 MPa in the asbuilt condition. Keywords
additive manufacturing, directed energy deposition, repair, stainless steel, tensile properties
1. Introduction Fabrication of components with complex geometries is one of the key innovations that additive manufacturing (AM) brings to metal fabrication (Ref 1-3). Directed energy deposition (DED) is an AM process (Ref 4) that uses a highly concentrated energy source, such as an electron beam or a laser, to create a melt pool at the surface of a base plate and either project powder or insert a wire feedstock into it to form a dense deposit. The projection/print head, the base plate, or a combination of the two, move in the XY plane according to the processed CAD file to deposit each layer with multiple parallel tracks. Once a layer is completed, the base plate or the print head moves along the Z-axis to a specific height increment (typically 250-500 lm (Ref 5)) and the next layer is deposited. This deposition process is repeated in an iterative way for each layer until the whole part is completed. A simplified schematic representation of a laser/powder DED system is presented in Fig. 1. DED can be used to repair parts that have been worn or damaged in service. This characteristic is particularly interestLouis Simoneau, Mining, Metallurgy and Materials Engineering, Universite´ Laval, Quebec, QC G1V 0A6, Canada; R&D, Centre de Me´tallurgie du Que´bec (CMQ), Trois-Rivie`res, QC G9A 5E1, Canada; and Rio Tinto – Aluminium, Jonquie`re, QC G7S 3B6, Canada; Alexandre Bois-Brochu, R&D, Centre de Me´tallurgie du Que´bec (CMQ), Trois-Rivie`res, QC G9A 5E1, Canada; and Carl Blais, Mining, Metallurgy and Materials Engineering, Universite´ Laval, Quebec, QC G1V 0A6, Canada. Contact e-mail: carl.blais@gmn.
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