Session: HT-06-01 Design and Analysis of High-Pressure Equipment for Oil and Gas Exploration and Production

Paper Number: 60453

Start Time: Wednesday, July 14, 2021, 09:00 AM

60453 - Hydrogen Embrittlement in Inconel 718 Produced by Selective Laser Melting 

Inconel 718 is widely used to produce components subjected to elevated temperatures and heavy loads. However, this alloy is also employed in aggressive environments promoting the production of hydrogen on the metal surface, such as high pressure and Oil&Gas applications. Selective Laser Melting (SLM) is an emerging technology for the production of structural components, thanks to its ability to create complex geometries and reduce material consumption. Components produced by SLM are typically characterized by a peculiar microstructure and residual stresses that can affect hydrogen migration and accumulation. While the mechanical properties and fatigue endurance were deeply investigated in recent years, the resistance of SLMed Inconel 718 to the Hydrogen Embrittlement (HE) requires further investigation.

The effects of the SLM process on reducing the strength and ductility of Inconel 718 were investigated. Standard tensile tests and slow strain rate tests were carried out on V-notched and unnotched specimens for different hydrogen concentrations. A coupled structural diffusion Finite Element model was developed and used to predict the hydrogen migration promoted by the hydrostatic stress gradients caused by the stress concentration in proximity to the notch apex. The results are discussed in the framework of hydrogen-assisted damage processes, and correlations between the hydrogen concentration and the mechanical strength under uniaxial and multiaxial stress state are derived.

Presenting Author: Giuseppe Macoretta Department of Civil and Industrial Engineering - University of Pisa

Authors:

Giuseppe Macoretta Department of Civil and Industrial Engineering - University of Pisa
Bernardo Disma Monelli Department of Civil and Industrial Engineering - University of Pisa
Marco Beghini Department of Civil and Industrial Engineering - University of Pisa
Renzo Valentini Department of Civil and Industrial Engineering - University of Pisa
Francesco Aiello Department of Civil and Industrial Engineering - University of Pisa
Mattia Moda Department of Civil and Industrial Engineering - University of Pisa