Effect of cold rolling on hydrogen diffusion and trapping in X70 pipeline steel

2020 ◽  
pp. 1-28
Author(s):  
Alen Thomas ◽  
Jerzy Szpunar
Keyword(s):  
Cold Rolling ◽  
Hydrogen Diffusion ◽  
Hydrogen Permeation ◽  
Pipeline Steel ◽  
Effective Diffusion ◽  
Diffusion Path ◽  
X70 Pipeline Steel ◽  
Diffusion Parameters ◽  
Intensity Changes ◽  
Diffusion Intensity

Abstract In this investigation, we prepared samples with five different grain misorientations by cold rolling an X70 pipeline steel plate. The hydrogen permeation and hydrogen visualization experiments were used to compute the diffusion parameters and to reveal the diffusion path in steel samples. The dual-polarized permeation experiment allowed us to show that permeability and effective diffusion coefficient were decreased with an increase in misorientation. Hence, the total and irreversible trapping sites were also raised with the extent of deformation in the steel. On the other hand, the visualization study permitted us to show that hydrogen diffusion intensity changes within the microstructure. The diffusion intensity increases in the order of non-deformed grains, grain boundaries and deformed grains with deformed grains as the easiest path for hydrogen diffusion.

scholarly journals Effect of Microstructure on Hydrogen Diffusion in Weld and API X52 Pipeline Steel Base Metals under Cathodic Protection

2017 ◽  
Vol 2017 ◽  
pp. 1-14 ◽  
Author(s):  
R. C. Souza ◽  
L. R. Pereira ◽  
L. M. Starling ◽  
J. N. Pereira ◽  
T. A. Simões ◽  
...  
Keyword(s):  
Corrosion Resistance ◽  
Weld Metal ◽  
Base Metal ◽  
Cathodic Protection ◽  
Hydrogen Diffusion ◽  
Hydrogen Permeation ◽  
Pipeline Steel ◽  
Sodium Thiosulfate ◽  
Hydrogen Flow ◽  
Electrochemical Tests

The aim of this research was to evaluate the influence of microstructure on hydrogen permeation of weld and API X52 base metal under cathodic protection. The microstructures analyzed were of the API X52, as received, quenched, and annealed, and the welded zone. The test was performed in base metal (BM), quenched base metal (QBM), annealed base metal (ABM), and weld metal (WM). Hydrogen permeation flows were evaluated using electrochemical tests in a Devanathan cell. The potentiodynamic polarization curves were carried out to evaluate the corrosion resistance of each microstructure. All tests were carried out in synthetic soil solutions NS4 and NS4 + sodium thiosulfate at 25°C. The sodium thiosulfate was used to simulate sulfate reduction bacteria (SRB). Through polarization, assays established that the microstructure does not influence the corrosion resistance. The permeation tests showed that weld metal had lower hydrogen flow than base metal as received, quenched, and annealed.

Study of Electrochemical Behavior, Hydrogen Permeation and Diffusion in Pipeline Steel

2021 ◽  
Vol 1019 ◽  
pp. 145-156
Author(s):  
Swapna Dey ◽  
Seetharaman Sivaprasad ◽  
Nityananda Das ◽  
Indranil Chattoraj
Keyword(s):  
Corrosion Behavior ◽  
Hydrogen Permeation ◽  
Pipeline Steel ◽  
Electrochemical Corrosion ◽  
Hydrogen Distribution ◽  
X70 Pipeline Steel ◽  
Hydrogen Flux ◽  
Hydrogen Damage ◽  
Internal Surfaces ◽  
Neutral Soil

The pipeline steels which are used for transportation of natural gas and crude oil suffer from hydrogen damage at their internal as well as external surfaces. The internal surfaces of pipelines are generally affected due to hydrogen induced cracking and the external surfaces due to the soil environmental conditions which cause stress corrosion cracking. In the present investigation, the electrochemical corrosion behavior of X70 pipeline steel was studied in sour environment and near neutral soil environment. To assess the mechanism of hydrogen damage in steel, electrochemical hydrogen charging and permeation techniques were used to characterize the hydrogen distribution, trapping and its diffusion in X70 pipeline steel. It has been found that corrosion behavior of pipeline steel in the sour environment is higher than the near neutral soil solution. From the hydrogen permeation study it is established that the hydrogen permeation rate increases with the square root of the charging current density, and the increase of hydrogen flux is directly proportional to the subsurface hydrogen concentration.

Hydrogen in the Plastic Deformed Steel

2007 ◽  
Vol 537-538 ◽  
pp. 33-40 ◽  
Author(s):  
Enikö Réka Fábián ◽  
László Dévényi
Keyword(s):  
Cold Rolling ◽  
Room Temperature ◽  
Hydrogen Diffusion ◽  
Hydrogen Permeation ◽  
Cold Work ◽  
Low Carbon ◽  
Steel Sheets ◽  
Metallic Inclusions ◽  
Dissolved Hydrogen ◽  
Grade Steel

The solubility of hydrogen in iron and steels are affected by temperature and crystal structure. At lower temperatures (below about 400°C), the excess hydrogen, beyond that which is soluble (and therefore dissolved) interstitially, is retained in the steel in other sites commonly referred to as ”traps”. At room temperature, the dissolved hydrogen may be only a small fraction of the total hydrogen content. The movement of hydrogen in steel occurs by the migration of atoms through the lattice. The hydrogen diffusion takes place with interstitial mechanism. Trapping enhances the solubility of hydrogen but decreases the diffusivity. In practice hydrogen transmissibility is characterized by TH value. We have studied the effect of the cold rolling on the TH value for Al-killed low carbon enamelling-grade steel sheets. The microstructures of the samples were formed from ferrite, carbides and some non-metallic inclusions. Reducing the thickness of the steel sheets by cold rolling in carbides appears ruptures, microcavities, and the dislocation density increases in ferrite grains. Cold work increases the hydrogen permeation time. The average of TH values after hot rolling was 0.6; after about 72 % thickness reductions by cold rolling the average TH values was 101.4.

Studies on Hydrogen Permeation of Weldments for Two Low-Alloyed Steels With Different Microstructures

2011 ◽  
Author(s):  
Jian Qun Tang ◽  
Jian Ming Gong
Keyword(s):  
Diffusion Coefficient ◽  
Hydrogen Diffusion ◽  
Hydrogen Permeation ◽  
Lath Martensite ◽  
Hydrogen Permeability ◽  
Diffusion Path ◽  
Permeation Rate ◽  
Liquefied Petroleum Gas ◽  
Boundary Area ◽  
And Diffusion

16MnR and SPV50Q low-alloyed steels, which have ferrite-pearlite and tempered martensite microstructures, respectively, are widely used to fabricate storage tanks for liquefied petroleum gas. However, during the process of operation, some cracks often occur on tanks made by these steels due to the presence of hydrogen, especially on weldments. The occurrence of this cracking is closely related to the diffusion and permeation of hydrogen in the steels. In order to explore the effect of different microstructures on hydrogen permeation and compare the hydrogen permeability of these two weldments, measurements were conducted on various metals (base metal-BM, heat-affected zone-HAZ, and welded metal-WM) cut from 16MnR and SPV50Q weldments by using electrochemical permeation tests. The results show that the microstructure has an important effect on hydrogen permeability. For 16MnR steel weldment, the diffusion coefficient of BM is the minimum due to the presence of the strong hydrogen traps in the interface between banded pearlite and matrix as well as the interface between inclusion and matrix. The microstructure of WM provides great grain boundary area as a hydrogen diffusion path and makes hydrogen easily diffuse, which results in the maximum permeation rate and diffusion coefficient. The fine-grained microstructure of normalized zone in HAZ acts as barriers for the hydrogen diffusion, which makes the permeation rate and diffusion coefficient of HAZ located between those of BM and WM. Similarly, for SPV50Q weldment, the permeation rate and diffusion coefficient increase in the order of BM, HAZ and WM. Those of BM are the minimum, which is correlated with the strong hydrogen trap due to the large quantities of dislocation within the lath martensite. Those of WM are the maximum for its strongly hydrogen diffusion path like WM of 16MnR weldment. As comparing the hydrogen permeability of 16MnR and SPV50Q weldment, the corresponding metals of the former always have greater permeation rate and diffusion coefficient than those of the latter, which is also due to its intrinsic microstructures.

STRESS CORROSION CRACK INITIATION BEHAVIOR FOR THE X70 PIPELINE STEEL BENEATH A DISBONDED COATING

2012 ◽  
Vol 48 (10) ◽  
pp. 1267 ◽  
Author(s):  
Zhiying WANG ◽  
Jianqiu WANG ◽  
En-hou HAN ◽  
Wei KE ◽  
Maocheng YAN ◽  
...  
Keyword(s):  
Crack Initiation ◽  
Stress Corrosion ◽  
Stress Corrosion Crack ◽  
Pipeline Steel ◽  
X70 Pipeline Steel ◽  
Disbonded Coating
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