Laser powder bed fused Inconel 718 in stress-relieved and solution heat-treated conditions

Hasani, N. and Dharmendra, C. and Sanjari, M. and Fazeli, F. and Amirkhiz, B.S. and Pirgazi, H. and G.D, Janaki Ram and et al, . (2021) Laser powder bed fused Inconel 718 in stress-relieved and solution heat-treated conditions. Materials Characterization, 181. pp. 1-16. ISSN 1044-5803

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Abstract

Inconel 718 superalloy cylindrical rods were fabricated using the laser powder bed fusion (L-PBF) technology in the vertical orientation. The rods were stress-relieved at 980 °C for 15 min before cutting them from the build plate. The microstructure in this condition exhibited a significant amount of undesirable needle-like δ-phase precipitates and a small amount of interdendritic Laves phase that is finer in size. Differential Scanning Calorimetry (DSC) was used to determine the temperatures for solid-state phase transformations and appropriate temperature for solution-treatment. Solution-treatment was performed at 1065 °C for 1 h, followed by air cooling. The microstructures were characterized with specific reference to δ-phase and Nb segregation. Solution-treatment at 1065 °C was found to result in a significant elimination of micro-segregation (mainly Nb), complete dissolution of δ phase, considerable Laves dissolution, and partly undissolved carbide particles (few nm in size). Solution-treatment did not produce a significant change in the grain morphology (columnar dendritic) on a plane parallel to the build direction but more recrystallized and equiaxed grains were formed on a plane perpendicular to the build direction. The hardness of the solution-treated sample is comparable with wrought 718 alloys but lesser (115 HV) than in the stress-relieved condition attributing to the annihilation of dislocation tangles. © 2021

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IITH Creators:

IITH Creators	ORCiD
G.D, Janaki Ram	UNSPECIFIED

Item Type:

Article

Additional Information:

The authors would like to thank Natural Sciences and Engineering Research Council of Canada (NSERC) grant number RGPIN-2016-04221 , New Brunswick Innovation Foundation (NBIF) grant number RIF2017-071 , Mitacs Accelerate Program grant number IT10669 , Atlantic Canada Opportunities Agency (ACOA) - Atlantic Innovation Fund (AIF) project number 210414 for providing financial support to conduct this work. The authors acknowledge the Gas Turbine Research Establishment (GTRE) in Banglore, India, for fabricating the Inconel 718 cylinders via LPBF. Special thanks to Vince Boardman and Brian Guidry at UNB-Mechanical Engineering for sample preparation and Dr. Douglas Hall and Steven Cogswell at UNB's Microscopy and Microanalysis Facility for SEM, Catherine Bibby and Pei Liu at CanmetMATERIALS for TEM sample preparations.

Uncontrolled Keywords:

Electron microscopy; Inconel 718; Laser powder bed fusion; Secondary phases; Solution treatment; Stress-relieving

Subjects:

Materials Engineering > Materials engineering

Divisions:

Department of Material Science Engineering

Depositing User:

. LibTrainee 2021

Date Deposited:

03 Sep 2022 05:44

Last Modified:

03 Sep 2022 05:44