scholarly journals The Effect of Microstructural Characteristics on the Hydrogen Permeation Transient in Quenched and Tempered Martensitic Alloys

Metals ◽  
2018 ◽  
Vol 8 (10) ◽  
pp. 779 ◽  
Author(s):  
E. Van den Eeckhout ◽  
T. Depover ◽  
K. Verbeken
Keyword(s):  
Hydrogen Diffusion ◽  
Hydrogen Permeation ◽  
Decisive Role ◽  
Thermal Desorption Spectroscopy ◽  
Ternary Alloys ◽  
Hydrogen Trapping ◽  
Microstructural Characteristics ◽  
Hydrogen Diffusion Coefficient ◽  
Tempering Treatment ◽  
Permeation Transient

This work evaluates the permeation curve characteristics for four quenched and tempered generic, ternary alloys, each containing one specific carbide. The different carbides (W2C, Cr23C6, TiC, and V4C3, respectively) are induced by a quench and tempering treatment. The correlation is made between the different microstructural characteristics, including the carbides and the martensitic matrix, and the observed hydrogen diffusivity and thus the permeation transient. The permeation curves, obtained via the Devanathan and Stachurski method, are therefore compared with thermal desorption spectroscopy and hot extraction results. The delay of the permeation transient can be associated with the overall trap density, while the slope is related to the amount of reversible trapping sites. Generally, the obtained hydrogen permeation transient of the different ternary or Fe–C–X materials correlates with the hydrogen trapping ability. The following order of hydrogen diffusion is determined, i.e., Fe–C–V < Fe–C–Ti << Fe–C–Cr < Fe–C–W. The hydrogen trapping ability of the tempered induced carbides plays a decisive role in the value of the hydrogen diffusion coefficient.

scholarly journals Numerical Study of Hydrogen Trapping: Application to an API 5L X60 Steel

2012 ◽  
Vol 2012 ◽  
pp. 1-14 ◽  
Author(s):  
Patricia Castaño-Rivera ◽  
Viviana P. Ramunni ◽  
Pablo Bruzzoni
Keyword(s):  
Hydrogen Permeation ◽  
Numerical Study ◽  
Local Equilibrium ◽  
Binding Energies ◽  
Hydrogen Trapping ◽  
Free Energies ◽  
Least Squares Fit ◽  
Permeation Transient ◽  
C 50 ◽  
Trapping Sites

A numerical finite difference method is developed here to solve the diffusion equation for hydrogen in presence of trapping sites. A feature of our software is that an optimization of diffusion and trapping parameters is achieved via a non linear least squares fit. On the other hand, we have demonstrated that usual electrochemical hydrogen permeation tests are enough to assess hydrogen free energies of trapping in the range of −35 kJ/mol to −70 kJ/mol. These conclusions are obtained by assuming the presence of saturable traps in local equilibrium with hydrogen and are validated by means of simulated permeation and degassing transients. In addition, we check our model performing electrochemical hydrogen permeation tests at 30°C, 50°C, and 70°C, on an API 5L X60 as received steel state to study its trapping and diffusion properties considering only one type of trapping site. The binding energies (ΔG) and the trap densities (N) are determined by fitting the theoretical model to the experimental permeation data. The steel presents a high density of weak traps, |ΔG|<35 KJ/mol, namely, N=1.4×10−5 mol cm−3. Strong trapping sites which alter the shape of the permeation transient are also detected; their ΔG values ranged from 57 to 72 KJ/mol.

Hydrogen Diffusion Coefficient during Hydrogen Permeation through Nb-Based Hydrogen Permeable Membranes

2009 ◽  
Vol 283-286 ◽  
pp. 225-230 ◽  
Author(s):  
Hiroshi Yukawa ◽  
G.X. Zhang ◽  
N. Watanabe ◽  
Masahiko Morinaga ◽  
T. Nambu ◽  
...  
Keyword(s):  
Crystal Structure ◽  
Diffusion Coefficient ◽  
High Temperature ◽  
Solid Solutions ◽  
Diffusion Coefficients ◽  
Hydrogen Diffusion ◽  
Hydrogen Permeation ◽  
Pure Niobium ◽  
Hydrogen Diffusion Coefficient

The hydrogen diffusion coefficients are investigated during the hydrogen permeation through Nb-based hydrogen permeable membranes at high temperature. It is found that the hydrogen diffusion coefficient for pure niobium under practical conditions is much lower than the reported values measured for dilute hydrogen solid solutions. Surprisingly, the hydrogen diffusion is found to be faster in Pd-Ag alloy with fcc crystal structure than in pure niobium with bcc crystal structure at 773K during the hydrogen permeation. It is also found that the addition of Ru or W into niobium increases the hydrogen diffusion coefficient under the practical conditions.

scholarly journals Hydrogen Diffusivity in Different Microstructures of 42CrMo4 Steel

Hydrogen ◽  
2021 ◽  
Vol 2 (4) ◽  
pp. 414-427
Author(s):  
Atif Imdad ◽  
Alfredo Zafra ◽  
Victor Arniella ◽  
Javier Belzunce
Keyword(s):  
Diffusion Coefficient ◽  
Hydrogen Diffusion ◽  
Hydrogen Permeation ◽  
Ferritic Steels ◽  
Hydrogen Diffusivity ◽  
Hydrogen Atoms ◽  
Hydrogen Diffusion Coefficient ◽  
Microstructural Defects ◽  
42Crmo4 Steel

It is well known that the presence of hydrogen decreases the mechanical properties of ferritic steels, giving rise to the phenomenon known as hydrogen embrittlement (HE). The sensitivity to HE increases with the strength of the steel due to the increase of its microstructural defects (hydrogen traps), which eventually increase hydrogen solubility and decrease hydrogen diffusivity in the steel. The aim of this work is to study hydrogen diffusivity in a 42CrMo4 steel submitted to different heat treatments—annealing, normalizing and quench and tempering—to obtain different microstructures, with a broad range of hardness levels. Electrochemical hydrogen permeation tests were performed in a modified Devanathan and Stachursky double-cell. The build-up transient methodology allowed the determination of the apparent hydrogen diffusion coefficient, Dapp, and assessment of its evolution during the progressive filling of the microstructural hydrogen traps. Consequently, the lattice hydrogen diffusion coefficient, DL, was determined. Optical and scanning electron microscopy (SEM) were employed to examine the steel microstructures in order to understand their interaction with hydrogen atoms. In general, the results show that the permeation parameters are strongly related to the steel hardness, being less affected by the type of microstructure.

Analysis of hydrogen diffusion coefficient during hydrogen permeation through niobium and its alloys

2009 ◽  
Vol 476 (1-2) ◽  
pp. 102-106 ◽  
Author(s):  
H. Yukawa ◽  
G.X. Zhang ◽  
N. Watanabe ◽  
M. Morinaga ◽  
T. Nambu ◽  
...  
Keyword(s):  
Diffusion Coefficient ◽  
Hydrogen Diffusion ◽  
Hydrogen Permeation ◽  
Hydrogen Diffusion Coefficient

Alloying Effects on the Hydrogen Diffusivity during Hydrogen Permeation through Nb-Based Hydrogen Permeable Membranes

2010 ◽  
Vol 297-301 ◽  
pp. 1091-1096 ◽  
Author(s):  
Hiroshi Yukawa ◽  
G.X. Zhang ◽  
Masahiko Morinaga ◽  
T. Nambu ◽  
Yoshihisa Matsumoto
Keyword(s):  
Activation Energy ◽  
Diffusion Coefficient ◽  
Hydrogen Diffusion ◽  
Hydrogen Permeation ◽  
Hydrogen Permeability ◽  
Hydrogen Diffusivity ◽  
Hydrogen Flux ◽  
Pure Niobium ◽  
Hydrogen Diffusion Coefficient ◽  
Alloying Effects

The hydrogen solubility and the hydrogen permeability have been measured for Nb-based alloys in order to investigate the alloying effects on the hydrogen diffusivity during hydrogen permeation. The hydrogen diffusion coefficient during hydrogen permeation is estimated from a linear relationship between the normalized hydrogen flux, , and the difference of hydrogen concentration, C, between the inlet and the outlet sides of the membrane. It is found that the hydrogen diffusion coefficient during the hydrogen permeation is increased by alloying ruthenium or tungsten into niobium. On the other hand, the activation energy for hydrogen diffusion in pure niobium under the practical permeation condition is much higher than the reported values measured for dilute hydrogen solid solutions. It is interesting that the activation energy for hydrogen diffusion decreases by the addition of ruthenium or tungsten into niobium.

Hydrogen Embrittlement and Hydrogen Trapping Behaviour in Advanced High Strength Steels

2021 ◽  
Vol 1016 ◽  
pp. 1344-1349
Author(s):  
Ali Smith
Keyword(s):  
Hydrogen Embrittlement ◽  
Retained Austenite ◽  
Hydrogen Diffusion ◽  
Hydrogen Permeation ◽  
High Strength Steels ◽  
High Strength ◽  
Hydrogen Trapping ◽  
Austenite Matrix ◽  
Advanced High Strength Steels ◽  
Step Loading

Modern advanced high strength steels (AHSS) for the automotive sector often contain retained austenite which promotes remarkable combinations of strength and ductility. These high strength steels may however be subject to a risk of hydrogen embrittlement. For the current contribution, hydrogen trapping and embrittlement behaviour were investigated in AHSS compositions having different levels of retained austenite. Hydrogen permeation tests revealed that hydrogen diffusion was slower for increased levels of retained austenite, being controlled most likely by reversible trapping at austenite-matrix interfaces. External hydrogen embrittlement tests via step loading also revealed that resistance to hydrogen was lower for increased levels of retained austenite. It was suggested that during step loading the hydrogen accumulated at austenite-matrix interfaces, leading to cracking when the applied stress was high enough.

Effect of Hydrogen Trapping and Poisons on Diffusion Behavior of Hydrogen in Low Carbon Steel

2018 ◽  
Vol 764 ◽  
pp. 3-10 ◽  
Author(s):  
Lian Cai ◽  
Li Min Zhao
Keyword(s):  
Carbon Steel ◽  
Hydrogen Diffusion ◽  
Hydrogen Permeation ◽  
Diffusion Flux ◽  
Low Carbon Steel ◽  
Low Carbon ◽  
Hydrogen Trapping ◽  
Diffusion Behavior ◽  
Hydrogen Charging ◽  
And Diffusion

Effect of hydrogen trapping and poisons on diffusion behavior of hydrogen in commercial cold-rolled low carbon steel was investigated by means of electrochemical hydrogen permeation techniques. The experimental results reveal that diffusion rate and diffusion flux of hydrogen in the materials gradually increase with increasing the number of hydrogen charging and outgassing, and lag time significantly shortens with them, therefore, hydrogen trapping impede diffusion behavior of hydrogen in the materials. Different poisons in the hydrogen charging solution have also resulted in a certain influence on the assessment of hydrogen diffusion behavior.

Analysis of hydrogen diffusion coefficient during hydrogen permeation through pure niobium

2008 ◽  
Vol 33 (16) ◽  
pp. 4419-4423 ◽  
Author(s):  
G ZHANG ◽  
H YUKAWA ◽  
N WATANABE ◽  
Y SAITO ◽  
H FUKAYA ◽  
...  
Keyword(s):  
Diffusion Coefficient ◽  
Hydrogen Diffusion ◽  
Hydrogen Permeation ◽  
Pure Niobium ◽  
Hydrogen Diffusion Coefficient
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