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.

scholarly journals Stress corrosion resistance of welded joints of low-alloy pipe steel produced by high frequency welding

2020 ◽  
Vol 61 (4) ◽  
pp. 328-338
Author(s):  
Lyudmila Nyrkova ◽  
Sergiy Prokopchuk ◽  
Svetlana Osadchuk ◽  
Anatoliy Rybakov ◽  
Larisa Goncharenko
Keyword(s):  
Heat Treatment ◽  
Corrosion Resistance ◽  
Weld Metal ◽  
Stress Corrosion ◽  
Base Metal ◽  
Cathodic Protection ◽  
Welded Joints ◽  
High Frequency ◽  
Welded Joint ◽  
Stress Corrosion Resistance

The paper presents the results of stress corrosion resistance studies of welded joints of low-alloy steel 17G1SU, obtained by high-frequency welding (HFW). The potentiometry method has established that the welded joint in the state after welding and after linear heat treatment is resistant to corrosion, because the potential difference between the weld and the base metal does not exceed (30-50) mV. According to the results of accelerated corrosion-mechanical tests in 3% NaCl under conditions of constant load under different stress, it was found that the rate of uniform corrosion of both types of welded joints is almost the same as the base metal. Slightly higher corrosion rate of the welded junction after linear heat treatment correlates with the electrochemical data. In general, the welded joint, made according to the factory technology, has resistance to corrosion and mechanical destruction in a solution of 3% NaCl at the level of the base metal, in the absence of weld defects. In the range of protective polarization potentials normalized by the standard of Ukraine, the ratio of the cathodic protection current to the diffusion current limit for the base metal and for the weld metal practically does not differ. It can be expected that under the conditions of cathodic protection, the predominant local flooding of the weld metal or the parent metal is not expected.

scholarly journals Correlation between Microstructure and Hydrogen Degradation of 690 MPa Grade Marine Engineering Steel

Materials ◽  
2021 ◽  
Vol 14 (4) ◽  
pp. 851
Author(s):  
Heng Ma ◽  
Huiyun Tian ◽  
Juncheng Xin ◽  
Zhongyu Cui
Keyword(s):  
Crack Propagation ◽  
Base Metal ◽  
Hydrogen Diffusion ◽  
Hydrogen Permeation ◽  
Steel Substrate ◽  
Phase Interface ◽  
Grain Structure ◽  
Hydrogen Degradation ◽  
Two Phase ◽  
Annealed Steel

Electrochemical H charging, hydrogen permeation, and hydrogen-induced cracking (HIC) behavior of 690 MPa grade steel substrate and different heat-treatment states (annealed, quenched, normalized, tempered) are investigated by cyclic voltammetry (CV), hydrogen permeation, electrochemical H charging, and slow strain rate tensile test (SSRT). The results show that hydrogen diffuses through the steel with the highest rate in base metal and the lowest rate in annealed steel. The hydrogen-induced cracks in base metal show obvious step shape with tiny cracks near the main crack. The cracks of annealed steel are mainly distributed along pearlite. The crack propagation of quenched steel is mainly transgranular, while the hydrogen-induced crack propagation of tempered steel is along the prior austenite grain boundary. HIC sensitivity of base metal is the lowest due to its fine homogeneous grain structure, small hydrogen diffusion coefficient, and small hydrogen diffusion rate. There are many hydrogen traps in annealed steel, such as the two-phase interface which provides accommodation sites for H atoms and increases the HIC susceptibility.

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.

Characteristics of Inconel 625 Filler Metal Affecting to Weld and Deposited Metal Zones in the Case of Welded to Forged Steel for Piston Crown Material

2014 ◽  
Vol 1004-1005 ◽  
pp. 1114-1119
Author(s):  
Sung Yul Lee ◽  
Kyung Man Moon ◽  
Jong Pil Won ◽  
Jae Hyun Jeong ◽  
Tae Sil Baek
Keyword(s):  
Corrosion Resistance ◽  
Weld Metal ◽  
Base Metal ◽  
Anodic Polarization ◽  
Corrosion Potential ◽  
Filler Metal ◽  
Polarization Curves ◽  
Inconel 625 ◽  
Piston Crown ◽  
Deposited Metal

Recently, wear and corrosion of the engine parts surrounded with combustion chamber is more serious compared to the other parts of the engine due to using of heavy oil of low quality. Therefore, an optimum repair welding for these parts is very important to prolong their lifetime in a economical point of view. In this study, Inconel 625 filler metal was welded with GTAW method in the forged steel which would be generally used with piston crown material. In this case, the mechanical and corrosion properties between weld metal zone (WM) welded to the groove which were artificially made in the base metal and deposited metal zone (DM) only welded by Inconel 625 filler metal on the surface of the base metal were investigated using electrochemical methods, such as measurement of corrosion potential, anodic polarization curves, cyclic voltammogram and impedance etc. in 35% H2SO4 solution. The deposited metal zone exhibited a better corrosion resistance compared to the weld metal zone, furthermore, its corrosion potential was a nobler value rather than that of the weld metal zone. However, the hardness indicated more or less higher value in the weld metal zone. The corrosive products after measurement of anodic polarization curves was hardly observed both in the weld and deposited zones, while, the morphologies of the corroded surfaces exhibited general and pitting corrosion in the weld and deposited metal zones respectively. The fine pearlite microstructure was a little observed in the weld metal zone, moreover, the microstructure of ferrite with elliptical pattern was significantly increased in the deposited metal zone. As a result, it is considered that the amount of Cr, Mo and Ni having a high corrosion resistance diffuse and migrate from the weld metal zone to the base metal zone, thus, the deposited metal zone indicated a better corrosion resistance than the weld metal zone because the amount of Cr, Mo and Ni were much involved in deposited metal zone compared to the weld metal zone.

Region-Specified Ratcheting Behavior of API X80 Welded Joint Under Uniaxial Cyclic Loading

2016 ◽  
Author(s):  
Hongsheng Lu ◽  
Yonghe Yang ◽  
Gang Chen ◽  
Xu Chen ◽  
Xin Wang
Keyword(s):  
Weld Metal ◽  
Base Metal ◽  
Heat Affected Zone ◽  
Welded Joint ◽  
Pipeline Steel ◽  
Coarse Grained ◽  
Strain Accumulation ◽  
Lower Strength ◽  
Fine Grained ◽  
Ratcheting Strain

Evaluation of mechanical performance of different regions can be difficult by using standard size samples due to the size limitation of weld metal and heat-affected zone (HAZ). At first, the microstructure of different regions was characterized and quantified by Scanning Electron Microscope, which indicate that the pipeline steel is a typical acicular ferrite steel. In this study the deformation behavior of different regions (base metal, weld metal and heat affected zone) in a welded joint of API X80 pipeline steel were studied by conducting uniaxial loading tests on miniature specimens with the cross section of 2×0.5mm and gauge length of 9mm. From the results of uniaxial tension in base metal and weld metal it is shown that the welding is overmatching. Compared to the base metal, the coarse grained HAZ exhibits a lower strength, while the fine grained HAZ exhibits a higher strength. Under near zero-to-tension cyclic stress loading, all regions of the welded joints exhibit progressive accumulation of plastic strain. Under the same stress level, the base metal shows the fastest ratcheting strain accumulation, which is the result of lower strength than other regions. This fact may indicate that the ratcheting behavior of the overall welded joint is highly dependence on that of base metal for the present case. But when under the same normalized stress level (σ = σ/σYS), the fine grained HAZ has the highest ratcheting strain accumulation, while the coarse grained HAZ has the lowest ratcheting strain accumulation, which reveals that the intrinsic resistance to ratcheting is yield strength dependent.

scholarly journals Corrosion Resistance of Pipeline Steel with Damaged Enamel Coating and Cathodic Protection

Coatings ◽  
2018 ◽  
Vol 8 (5) ◽  
pp. 185 ◽  
Author(s):  
Liang Fan ◽  
Signo Reis ◽  
Genda Chen ◽  
Michael Koenigstein
Keyword(s):  
Corrosion Resistance ◽  
Cathodic Protection ◽  
Enamel Coating ◽  
Pipeline Steel

Experimental investigation of structural integrity behavior of High strength low alloy steel – Study of mechanical, microstructural and corrosion behavior of Submerged arc welding weldments

2020 ◽  
pp. 095440892095810
Author(s):  
Lochan Sharma ◽  
Rahul Chhibber
Keyword(s):  
Corrosion Resistance ◽  
Impact Strength ◽  
Weld Metal ◽  
Base Metal ◽  
Arc Welding ◽  
Weld Zone ◽  
Submerged Arc Welding ◽  
Welding Fluxes ◽  
Submerged Arc ◽  
Metal Impact

The present study aims at investigating the effect of submerged arc welding fluxes for enhanced corrosion resistance of structural steel welds. By varying the basicity index of submerged arc welding fluxes the corrosion resistance and mechanical properties of weld metal such as tensile strength, impact strength, microhardness in submerged arc weldments were evaluated. The result shows that with the increase in bascity index tensile strength of weld specimen reduced while impact strength and microhardness value increased. Maximum microhardness (288 HV) was observed for flux 2 while base metal show minimum microhardness value (205 HV). Flux 5 gives maximum impact strength (94.17 J) as compared to the base metal (80 J). This is due to the reduced content of oxygen in weld metal which increases the weld metal impact toughness. Corrosion resistance of weld specimen increased as compared to the base metal. Ductile fracture mode and shear lip or tears were observed in the weld zone. Shear dimples and shear lips were more severe in base metal as well as weld metal impact specimens due to the rapid effect of external forces on the impact test. The banded microstructure of delta ferrite and austenite was observed in the base metal. Fine grains of ferrite and pearlite at the center and edges were present in the weld zone.

Corrosion Resistance and Galvanic Coupling of UNS N08031 Base Metal, Heat-Affected Zone, and Weld Metal in Phosphoric Acid at Different Temperatures

CORROSION ◽  
2011 ◽  
Vol 67 (3) ◽  
pp. 035001-1-035001-10 ◽  
Author(s):  
E. Blasco-Tamarit ◽  
D.M. García-García ◽  
M. Ibáñez Ferrándiz ◽  
J. García Antón ◽  
A. Guenbour
Keyword(s):  
Corrosion Resistance ◽  
Phosphoric Acid ◽  
Weld Metal ◽  
Base Metal ◽  
Heat Affected Zone ◽  
Galvanic Coupling ◽  
Different Temperatures

scholarly journals Twin-Wire Pulsed Tandem Gas Metal Arc Welding of API X80 Steel Linepipe

2018 ◽  
Vol 2018 ◽  
pp. 1-11
Author(s):  
Wenhao Wu ◽  
Ming Zhao ◽  
Haiyan Wang ◽  
Yanxia Zhang ◽  
Tong Wu
Keyword(s):  
Corrosion Resistance ◽  
Weld Metal ◽  
Base Metal ◽  
Corrosion Behavior ◽  
Arc Welding ◽  
Production Efficiency ◽  
Gas Metal Arc Welding ◽  
Welding Process ◽  
Metal Arc Welding ◽  
X80 Steel

Twin-Wire Pulsed Tandem Gas Metal Arc Welding process with high welding production efficiency was used to join the girth weld seam of API X80 steel linepipe of 18.4 mm wall thickness and 1422 mm diameter. The macrostructure, microstructure, hardness, and electrochemical corrosion behavior of welded joints were studied. Effects of temperature and Cl− concentration on the corrosion behavior of base metal and weld metal were investigated. Results show that the welded joint has good morphology, mechanical properties, and corrosion resistance. The corrosion resistance of both the base metal and the weld metal decreases with increasing temperature or Cl− concentration. In the solution with high Cl− concentration, the base metal and weld metal are more susceptible to pitting. The corrosion resistance of the weld metal is slightly lower than that of the base metal.

scholarly journals Microstructure, roughness, and corrosion resistance of X5CrNi18-10 austenite stainless steel welded joint

2021 ◽  
pp. 7-7
Author(s):  
Bojana Radojkovic ◽  
Bore Jegdic ◽  
Jovanka Kovacina ◽  
Sanja Stevanovic ◽  
Dunja Marunkic
Keyword(s):  
Stainless Steel ◽  
Corrosion Resistance ◽  
Weld Metal ◽  
Base Metal ◽  
Pitting Corrosion ◽  
Welded Joint ◽  
Electrochemical Testing ◽  
Limit Value ◽  
Before And After ◽  
Degree Of Sensitization

The influence of the microstructure of the X5CrNi18-10 stainless steel welded joint on its resistance to general, pitting, and intergranular corrosion was analysed. The structure of weld metal, heat affected zone (HAZ) and base metal before and after electrochemical testing was analysed using SEM/EDS. The influence of the roughness level of the welded joint on its resistance to the mentioned types of corrosion was examined as well. Although the degree of sensitization of HAZ was significantly lower than the limit value, HAZ showed a noticeably greater tendency to general and pitting corrosion than weld metal and base metal. Polishing has been shown to significantly improve the corrosion resistance of HAZ than in the case of other parts of the welded joint.

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