scholarly journals Thickness and microstructure effect on hydrogen diffusion in creep-resistant 9% Cr P92 steel and P91 weld metal

2021 ◽  
Author(s):  
Michael Rhode ◽  
Tim Richter ◽  
Tobias Mente ◽  
Peter Mayr ◽  
Alexander Nitsche
Keyword(s):  
Weld Metal ◽  
Diffusion Coefficients ◽  
Hydrogen Diffusion ◽  
Time Lag ◽  
P92 Steel ◽  
Carrier Gas Hot Extraction ◽  
Temperature Diffusion ◽  
Hydrogen Assisted Cracking ◽  
Heat Treated Condition ◽  
Microstructure Effect

Abstract Martensitic 9% Cr steels like P91 and P92 show susceptibility to delayed hydrogen assisted cracking depending on their microstructure. In that connection, effective hydrogen diffusion coefficients are used to assess the possible time-delay. Limited data on room temperature diffusion coefficients reported in literature vary widely by several orders of magnitude (mostly attributed to variation in microstructure). Especially P91 weld metal diffusion coefficients are rare so far. For that reason, electrochemical permeation experiments had been conducted using P92 base metal and P91 weld metal (in as-welded and heat-treated condition) with different thicknesses. From the results obtained, diffusion coefficients were calculated using to different methods, time-lag, and inflection point. Results show that, despite microstructural effects, the sample thickness must be considered as it influences the calculated diffusion coefficients. Finally, the comparison of calculated and measured hydrogen concentrations (determined by carrier gas hot extraction) enables the identification of realistic diffusion coefficients.

Hydrogen Diffusion Coefficients in Ferrovac 1020 and Cr-Mo Alloy Steels

CORROSION ◽  
1976 ◽  
Vol 32 (5) ◽  
pp. 179-183 ◽  
Author(s):  
OLIMPIO F. ANGELES ◽  
RICHARD J. STUEBER ◽  
GORDON H. GEIGER
Keyword(s):  
Diffusion Coefficient ◽  
Diffusion Coefficients ◽  
Hydrogen Diffusion ◽  
Time Lag ◽  
Alloy Steels

Abstract Hydrogen diffusion coefficients were measured in Ferrovac 1020 and several Cr-Mo alloy steels at temperatures between 700 and 1150 F (370 and 620 C), using the time-lag method. Alloying was found to decrease the diffusion coefficient.

Anwendung elektrochemischer Verfahren zur Untersuchung der Diffusion von Wasserstoff-Isotopen in V, Nb und Ta / Application of Electrochemical Techniques for Studying Diffusion of Hydrogen Isotopes in V, Nb and Ta

1976 ◽  
Vol 31 (7) ◽  
pp. 760-768
Author(s):  
N. Boes ◽  
H. Züchner
Keyword(s):  
Diffusion Process ◽  
Diffusion Coefficients ◽  
Hydrogen Diffusion ◽  
Tetrahedral Site ◽  
Electrochemical Techniques ◽  
Time Lag ◽  
Tetrahedral Sites ◽  
Dissolved Hydrogen ◽  
Strain Model ◽  
Diffusion Of Hydrogen

Abstract After suitable preparation (improvement) of samples H (D) -diffusion coefficients of V-, Nb-, and Ta-foils can be measured reliably at low H (D) -concentrations in the temperature range 0 to 100 °C by means of an electrochemical time-lag method. A modified strain model indicates that the tetrahedral sites in bcc lattices have to be taken as the stable positions for the dissolved hydrogen. The elementary jump in the diffusion process from one tetrahedral site to the next passes directly through a tetrahedral plane. This model describes qualitatively the experimental results concerning the sequence of the activation energies for hydrogen diffusion in the three Vb-metals [E(Ta)>E(Nb)>E(V)].

Determination of Hydrogen Diffusion Coefficients in F82H by Hydrogen Depth Profiling with a Tritium Imaging Plate Technique

2015 ◽  
Vol 67 (2) ◽  
pp. 379-381 ◽  
Author(s):  
M. Higaki ◽  
T. Otsuka ◽  
K. Tokunaga ◽  
K. Hashizume ◽  
K. Ezato ◽  
...  
Keyword(s):  
Diffusion Coefficients ◽  
Hydrogen Diffusion ◽  
Depth Profiling ◽  
Imaging Plate ◽  
Plate Technique

Effective hydrogen diffusivities of AISI 304 stainless steel with Ni or Au coating

2020 ◽  
Vol 62 (6) ◽  
pp. 593-596
Author(s):  
Krittayot Wannapoklang ◽  
Sirichai Leelachao ◽  
Anchaleeporn W. Lothongkum ◽  
Gobboon Lothongkum
Keyword(s):  
Stainless Steel ◽  
Hydrogen Diffusion ◽  
304 Stainless Steel ◽  
Phase Identification ◽  
Aisi 304 Stainless Steel ◽  
Aisi 304 ◽  
304 Austenitic Stainless Steel ◽  
Hydrogen Assisted Cracking ◽  
Stainless Steel Coupon ◽  
Effective Hydrogen

AbstractMetallic coatings which provide a hydrogen diffusion barrier are thought to reduce hydrogen assisted cracking on stainless steel. The influence of a metallic layer on the hydrogen migration of AISI 304 stainless steel was investigated using a commercial electroplating layer of Ni and Au on a thin stainless steel coupon. Phase identification was performed using an X-ray diffractometer to determine the average thicknesses, measured from back-scattered scanning electron images. Regarding the ASTM G148-97 practice, the effective hydrogen diffusivities of AISI 304 austenitic stainless steel, nickel and gold were measured as 7.07 × 10-13, 2.72 × 10-14 and 9.64 × 10-16 m2 × s-1, respectively. In this work, a gold layer was found to be most effective for the prevention of hydrogen diffusion when compared with untreated and Ni-plated 304 stainless steel.

Machine learning assisted design of FeCoNiCrMn high-entropy alloys with ultra-low hydrogen diffusion coefficients

2021 ◽  
pp. 117535
Author(s):  
Xiao-Ye Zhou ◽  
Ji-Hua Zhu ◽  
Yuan Wu ◽  
Xu-Sheng Yang ◽  
Turab Lookman ◽  
...  
Keyword(s):  
Machine Learning ◽  
Diffusion Coefficients ◽  
Hydrogen Diffusion ◽  
High Entropy Alloys ◽  
High Entropy

scholarly journals Hydrogen-assisted cracking in GMA welding of high-strength structural steels using the modified spray arc process

2020 ◽  
Vol 64 (12) ◽  
pp. 1997-2009
Author(s):  
Thomas Schaupp ◽  
Michael Rhode ◽  
Hamza Yahyaoui ◽  
Thomas Kannengiesser
Keyword(s):  
Weld Metal ◽  
Gma Welding ◽  
High Strength ◽  
Economic Benefits ◽  
Structural Steels ◽  
Test Series ◽  
Deposition Rates ◽  
The Past ◽  
Hydrogen Assisted Cracking ◽  
Implant Test

Abstract High-strength structural steels are used in machine, steel, and crane construction with yield strength up to 960 MPa. However, welding of these steels requires profound knowledge of three factors in terms of avoidance of hydrogen-assisted cracking (HAC): the interaction of microstructure, local stress/strain, and local hydrogen concentration. In addition to the three main factors, the used arc process is also important for the performance of the welded joint. In the past, the conventional transitional arc process (Conv. A) was mainly used for welding of high-strength steel grades. In the past decade, the so-called modified spray arc process (Mod. SA) has been increasingly used for welding production. This modified process enables reduced seam opening angles with increased deposition rates compared with the Conv. A. Economic benefits of using this arc type are a reduction of necessary weld beads and required filler material. In the present study, the susceptibility to HAC in the heat-affected zone (HAZ) of the high-strength structural steel S960QL was investigated with the externally loaded implant test. For that purpose, both Conv. A and Mod. SA were used with same heat input at different deposition rates. Both conducted test series showed same embrittlement index “EI” of 0.21 at diffusible hydrogen concentrations of 1.3 to 1.6 ml/100 g of arc weld metal. The fracture occurred in the HAZ or in the weld metal (WM). However, the test series with Mod. SA showed a significant extension of the time to failure of several hours compared with tests carried out with Conv. A.

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 Highly Permeable Matrimid®/PIM-EA(H2)-TB Blend Membrane for Gas Separation

Polymers ◽  
2018 ◽  
Vol 11 (1) ◽  
pp. 46 ◽  
Author(s):  
Elisa Esposito ◽  
Irene Mazzei ◽  
Marcello Monteleone ◽  
Alessio Fuoco ◽  
Mariolino Carta ◽  
...  
Keyword(s):  
Diffusion Coefficients ◽  
Gas Transport ◽  
Gas Permeability ◽  
Time Lag ◽  
Gas Diffusion ◽  
Gas Permeation ◽  
Spectrometric Analysis ◽  
Competitive Sorption ◽  
Transport Parameters ◽  
Mixed Gas

The effect on the gas transport properties of Matrimid®5218 of blending with the polymer of intrinsic microporosity PIM-EA(H2)-TB was studied by pure and mixed gas permeation measurements. Membranes of the two neat polymers and their 50/50 wt % blend were prepared by solution casting from a dilute solution in dichloromethane. The pure gas permeability and diffusion coefficients of H2, He, O2, N2, CO2 and CH4 were determined by the time lag method in a traditional fixed volume gas permeation setup. Mixed gas permeability measurements with a 35/65 vol % CO2/CH4 mixture and a 15/85 vol % CO2/N2 mixture were performed on a novel variable volume setup with on-line mass spectrometric analysis of the permeate composition, with the unique feature that it is also able to determine the mixed gas diffusion coefficients. It was found that the permeability of Matrimid increased approximately 20-fold with the addition of 50 wt % PIM-EA(H2)-TB. Mixed gas permeation measurements showed a slightly stronger pressure dependence for selectivity of separation of the CO2/CH4 mixture as compared to the CO2/N2 mixture, particularly for both the blended membrane and the pure PIM. The mixed gas selectivity was slightly higher than for pure gases, and although N2 and CH4 diffusion coefficients strongly increase in the presence of CO2, their solubility is dramatically reduced as a result of competitive sorption. A full analysis is provided of the difference between the pure and mixed gas transport parameters of PIM-EA(H2)-TB, Matrimid®5218 and their 50:50 wt % blend, including unique mixed gas diffusion coefficients.

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