Environmentally Assisted Cracking: Theory and Practice: Hydrogen Embrittlement I
Sponsored by: TMS Structural Materials Division, TMS: Corrosion and Environmental Effects Committee
Program Organizers: Bai Cui, University of Nebraska Lincoln; Raul Rebak, GE Global Research; Srujan Rokkam, Advanced Cooling Technologies, Inc.; Jenifer Locke, Ohio State University
Monday 2:00 PM
March 20, 2023
Room: Sapphire 410B
Location: Hilton
Session Chair: Dierk Raabe, Max-Planck Institute; Haozheng Qu, GE Global Research
2:00 PM Cancelled
Hydrogen Affecting Defect Density and Mobility in Metals and Vice Versa: Reiner Kirchheim1; 1University of Goettingen
Defects like vacancies, dislocations and grain boundaries are discontinuities of the crystal lattice and may attract hydrogen atoms leading to a higher solubility of hydrogen at a given pressure of hydrogen gas. On the other hand, hydrogen may either enhance or retard defect motion. Hydrogen also affects the generation of defects reducing their formation energies to zero, which is the main reason for hydrogen embrittlement of metals or more generally the plastic response of metals under external stress. It will be shown that other solutes as carbon, nitrogen and oxygen act the same as hydrogen on the defect generation. Solute atoms reducing defect formation energies will be called defactants (defect acting agents) in analogy to surfactants (surface acting agents) reducing surface formation energies. The basic physico-chemical laws describing this behavior of hydrogen are presented together with examples of experiments, where these laws are verified or play a major role.
2:30 PM
Some Recent Advances on Hydrogen Embrittlement in Martensitic Steels: From Diffusion and Trapping of Hydrogen to Mechanisms of Damage: Abdelali Oudriss1; Xavier Feaugas1; 1Lasie Cnrs Umr 7356
Hydrogen diffusion and trapping mechanisms have been revisited in martensitic steels with a large variability of microstructural parameters. An accurate electrochemical permeation set-up associated with thermal desorption spectroscopy and elastic theoretical calculations was used to find a relationship between physical parameters associated with diffusion, trapping and microstructure. The different sites of hydrogen and associated energy were identified and discussed in relation with microstructural features. Using FEM calculations and a new design of permeation testing under tensile loading until fracture we revisit the question of hydrogen embrittlement of martensitic steel. More precisely, we explore the impact of mobile and trapped hydrogen on ductile and brittle fracture of martensitic steel using a local approach of fracture and a specific analysis of the defect evolution under hydrogen flux (vacancies and dislocations). We discussed damage conditions in relation with the mechanical state using tensile samples with different notch for two conditions.
2:50 PM
Effect of Hydrogen on the Deformation of Austenitic Stainless Steels: A Stress Orientation Dependent Contribution?: Fernando Leon-Cazares1; Samuel Parry1; Brian Kagay2; Xiaowang Zhou1; Coleman Alleman1; Joseph Ronevich1; Chris San Marchi1; 1Sandia National Laboratories; 2MPA University of Stuttgart
Austenitic stainless steels are widely used in high-pressure hydrogen storage and delivery systems. Internal hydrogen is known to harden and embrittle these alloys, but its interactions with dislocations under varied stress states are not fully understood. This study investigates a potential anisotropic yield behavior of alloy 316L promoted by hydrogen, in which its contribution to the critical resolved shear stress has been reported to depend on stress orientation. Tension and compression tests are performed on hydrogen-precharged single crystals along multiple crystallographic directions to assess the roles of non-Schmid stress components. Molecular dynamics simulations are employed to investigate the effects of interstitial hydrogen, vacancies and hydrogen-vacancy complexes on the critical resolved shear stress for varied stress orientations, and a finite element crystal plasticity model is used to capture the emergent deformation behaviors. Hydrogen is shown to affect the deformation microstructure in varied ways, but deviations from Schmid’s law are not reproducible.
3:10 PM
Understanding Hydrogen Embrittlement Effects on the Deformation Mechanisms in Developmental Austenitic Steels: Quinten Yurek1; Po-Cheng Kung1; Hoon Lee2; James Stubbins3; Brian Somerday4; Petros Sofronis4; Tsuchiyama Toshihiro5; Jessica Krogstad1; 1Department of Materials Science and Engineering, University of Illinois at Urbana-Champaign; 2Department of Nuclear, Plasma and Radiological Engineering, University of Illinois at Urbana-Champaign ; 3Department of Nuclear, Plasma and Radiological Engineering, University of Illinois at Urbana-Champaign; 4Department of Mechanical Science and Engineering, University of Illinois at Urbana-Champaign; 5Department of Materials Science and Engineering, Kyushu University
In an effort to reduce the Ni content, and thus cost per kg of hydrogen resilient metals, we have investigated one commercial and four developmental austenitic stainless steels. Deformation microstructures are consistent across the novel and commercial alloys when tested under ambient conditions (room temperature, without hydrogen charging). However, deformation up to 10% strain of the same alloys subjected to hydrogen charging (138 MPa/300oC/816h) resulted in notable differences amongst the deformation microstructures as documented via SEM, EBSD, and TEM analysis. SEM and EBSD reveal intragranular cracking and deformation twinning in the high-Mn alloy. Furthermore, comparative analysis reveals differing degrees of slip localization and a correspondingly broader distribution of partial dislocation separation in hydrogen-charged alloys. This work provides important insight on the relationships between alloy composition and deformation behavior in the presence of hydrogen.
3:30 PM Break
3:50 PM Invited
Atomic-scale Analysis of Hydrogen Embrittlement in High-strength Al Alloys: Dierk Raabe1; Huan Zhao1; Batiste Gault1; Tilmann Hickel1; Dirk Ponge1; Binhan Sun1; 1Max-Planck Institute
we performed atomic-scale analysis of H trapped in second-phase particles and at grain boundaries in a high-strength 7xxx Al alloy. We used these observations to guide atomistic ab initio calculations, which show that theco-segregation of alloying elements and H favours grain boundary decohesion, and the strong partitioning of H into the second-phase particles removes solute H from the matrix, hence preventing H embrittlement. Our insights further advance the mechanistic understanding of H-assisted embrittlement in Al alloys, emphasizing the role of H traps in minimizing cracking and guiding new alloy design.
4:20 PM
Mechanical Behavior of Wrought Aluminum in Hydrogen Environments: Adam Freund1; Kester Clarke1; Amy Clarke1; Suveen Mathaudhu1; 1Colorado School of Mines
Aluminum alloys are of interest for hydrogen environments due to their natural passivating layer providing resistance to hydrogen incursion. However, in service, these alloys can face degradation when exposed to moisture under applied loading. Hydrogen embrittlement studies to date have focused primarily on the as-cast, homogenized, and aged states, however there is a lack of information on embrittlement behavior and mechanisms in wrought materials. In this study, Al alloys are prepared via rolling to different reductions, and mechanically tested in humid air to promote hydrogen ingress. The effects of composition, microstructure, dislocation density and/or grain boundary density on hydrogen trapping will be investigated via post-mortem chemical and microstructural analyses. The knowledge gained from this study will enable the expansion of our fundamental understanding of embrittlement mechanisms for the design of hydrogen resilient aluminum alloys.
4:40 PM
The Impacts of Hydrogen on the Elasticity, Plasticity and Damage Mechanisms of Pure Nickel: Abdelali Oudriss1; Siva Pasad Murugan1; Yasmine Ben Jedidia1; Nadjib Iskounen1; Marie Landeiro Dos Reis1; Jamaa Bouhattate1; Xavier Feaugas1; 1Lasie Cnrs Umr 7356
One of the fundamental aspects of hydrogen embrittlement is based on the impact of hydrogen on the elementary mechanisms of plasticity. Though it is well known that hydrogen deteriorates the ductility of nickel, there are antagonistic aspects in the hydrogen effects on plasticity, i.e., hydrogen-induced hardening as well as softening in metallic materials. These antagonist effects can influence the hydrogen-assisted damage mechanisms which can occur for nickel. This work aims to evaluate the impact of hydrogen on the plasticity of pure nickel single crystals, bicrystals and polycristals using different experimental multiscale approaches such as nanoindentation, microtensile and loading-unloading tests coupled to SEM-EBSD. The experimental results obtained were confronted with atomistic calculations in order to question the elementary mechanisms of plasticity in the presence of hydrogen and other defects such as vacancies and grain boundaries. Finally, all these interactions will also be questioned with respect to hydrogen-assisted damage modes.
5:00 PM
A Combined Micromechanics/Materials Science Approach to Understanding High Temperature Hydrogen Attack: Kshitij Vijayvargia1; Mohsen Dadfarnia2; Petros Sofronis1; Masanobu Kubota3; Aleksandar Staykov3; Kentarou Wada3; John Pugh4; Tom Eason5; 1University of Illinois Urbana-Champaign; 2Seattle University; 3International Institute for Carbon Neutral Energy Research; 4Other; 5BP Products North America
High temperature hydrogen attack (HTHA) is degradation of carbon steels whereby internal hydrogen reacting with carbides forms methane gas bubbles typically on grain boundaries which grow and coalesce, leading to loss of strength and toughness. Current design practice against HTHA is based on Nelson curves which define the conditions for safe operation in a temperature/hydrogen-partial-pressure diagram. Nelson curves are phenomenological and do not account for the underlying failure mechanism(s), microstructure, carbide stability, and applied stresses. To this end, we present a micromechanical model for predicting void growth and coalescence in carbon steels due to methane pressure and external loads. The methane gas pressure was calculated by combining kinetics-based modeling with density functional theory. The effect of hydrogen on the constitutive response was quantified by determining the activation parameters that govern the deformation during HTHA. The micromechanical model is used to construct physically-based Nelson-type curves indicating lifetime under given applied stresses.