Abstract
Hydrogen embrittlement (HE) is a known phenomenon in Ni and its alloys. It has led to a number of documented failures in the oil and gas industry in the past and poses a potential threat to the new era of a hydrogen economy, where hydrogen plays one of the leading roles as a CO2 emission-free energy carrier of the future. This problem calls for intelligent solutions for the design of new HE-resistant materials for the current and future applications in hydrogen-bearing environments.
In this work, we present the results of a multiscale HE research study of a high-strength Ni-base alloy with a focus on grain boundary (GB) embrittlement under hydrogen charging conditions. The methods of investigation comprise density functional theory (DFT) investigation of hydrogen enhanced GB decohesion (HEDE) and GB analysis, atom probe tomography study of the GB segregation, micromechanical micro-cantilever testing using in situ electrochemical H charging and macroscopic tensile testing after electrochemical H charging (ex-situ). The aforementioned methods are used to investigate the effect of hydrogen on the HE resistance of selected Ni-base alloys and to propose a concept to improve their resistance to HEDE. The concept is validated by the production, characterization and testing of a new alloy with improved HE resistance.