Hydrogen embrittlement in different materials: A review

The synergistic action and interplay of hydrogen embrittlement mechanisms in steels and iron: Localized plasticity and decohesion

Hydrogen embrittlement is a complex phenomenon, involving several length- and timescales, that affects a large class of metals. It can significantly reduce the ductility and load-bearing capacity and cause cracking and catastrophic brittle failures at stresses below the yield stress of susceptible materials. Despite a large research effort in attempting to understand the mechanisms of failure and in developing potential mitigating solutions, hydrogen embrittlement mechanisms are still not completely understood. There are controversial opinions in the literature regarding the underlying mechanisms and related experimental evidence supporting each of these theories. The aim of this paper is to provide a detailed review up to the current state of the art on the effect of hydrogen on the degradation of metals, with a particular focus on steels. Here, we describe the effect of hydrogen in steels from the atomistic to the continuum scale by reporting theoretical evidence supported by quantum calculation and modern experimental characterisation methods, macroscopic effects that influence the mechanical properties of steels and established damaging mechanisms for the embrittlement of steels. Furthermore, we give an insight into current approaches and new mitigation strategies used to design new steels resistant to hydrogen embrittlement.

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Understanding and mitigating hydrogen embrittlement of steels: a review of experimental, modelling and design progress from atomistic to continuum.

Metallographic Methods for Revealing the Multiphase Microstructure of TRIP-Assisted Steels - some applications for steels

The detrimental effect of hydrogen at dislocations on the hydrogen embrittlement susceptibility of Fe-C-X alloys: An experimental proof of the HELP mechanism

Microstructural characterization of hydrogen induced cracking in TRIP-assisted steel by EBSD

Abstract The present work evaluates hydrogen induced cracking by performing an elaborate EBSD (Electron BackScatter Diffraction) study in a steel with transformation induced plasticity (TRIP-assisted steel). This type of steel exhibits a multiphase microstructure which undergoes a deformation induced phase transformation. Additionally, each microstructural constituent displays a different behavior in the presence of hydrogen. The aim of this study is to obtain a better understanding on the mechanisms governing hydrogen induced crack initiation and propagation in the hydrogen saturated multiphase structure. Tensile tests on notched samples combined with in-situ electrochemical hydrogen charging were conducted. The tests were interrupted at stresses just after reaching the tensile strength, i.e. before macroscopic failure of the material. This allowed to study hydrogen induced crack initiation and propagation by SEM (Scanning Electron Microscopy) and EBSD. A correlation was found between the presence of martensite, which is known to be very susceptible to hydrogen embrittlement, and the initiation of hydrogen induced cracks. Initiation seems to occur mostly by martensite decohesion. High strain regions surrounding the hydrogen induced crack tips indicate that further crack propagation may have occurred by the HELP (hydrogen-enhanced localized plasticity) mechanism. Small hydrogen induced cracks located nearby the notch are typically S-shaped and crack propagation was dominantly transgranularly. The second stage of crack propagation consists of stepwise cracking by coalescence of small hydrogen induced cracks.

https://biblio.ugent.be/publication/8587447/file/8587448.pdf

Microstructural characterization of hydrogen induced cracking in TRIP-assisted steels by EBSD

Effect of deformation and charging conditions on crack and blister formation during electrochemical hydrogen charging

Characterization of hydrogen induced cracking in TRIP-assisted steels

The goal of this study is to obtain a deeper insight in the relation between hydrogen diffusion and hydrogen traps present in Armco pure iron. Cold deformation was applied to this material, which initially contained a limited amount of traps. The cold deformation was applied to increase the dislocation density and modify grain boundary characteristics. In this way, the hydrogen diffusivity decreased as the hydrogen trapping ability of the microstructure increased. A subsequent heat treatment allowed changing the density of microstructural defects again and consequently increased the hydrogen diffusion coefficient. In addition, studying blister formation showed that a higher degree of deformation caused more surface blisters, while recovery lowered the number of blisters. Electron backscatter diffraction characterisation provided the necessary input on the microstructural features and their evolution. Analysis of these samples allowed evaluating the correlation between hydrogen diffusion, blister f...

Aurélie Laureys

Papers

Microstructural characterization of hydrogen induced cracking in TRIP-assisted steel by EBSD

Microstructural characterization of hydrogen induced cracking in TRIP-assisted steels by EBSD

Effect of deformation and charging conditions on crack and blister formation during electrochemical hydrogen charging

Characterization of hydrogen induced cracking in TRIP-assisted steels

Hydrogen permeation through deformed and heat-treated Armco pure iron