X80 Pipeline Steel Research Articles

Effect of dissolved oxygen on corrosion behavior and mechanism of X70 pipeline steel in simulated low temperature bentonite-containing alkaline chloride environment

Effect of dissolved oxygen (DO) on the corrosion behavior of X70 pipeline steel in low temperature bentonite-containing alkaline chloride environments was comprehensively investigated. The cathodic reduction reaction is inhibited and corrosion current density gradually descent as the DO decreases, resulting in a significant improvement in the corrosion resistance of X70 pipeline steel. The content of Fe3O4 and α-FeOOH in the corrosion products film increases, refinement of rust grains and crack decreases effectively suppressing the penetration of corrosive substances. Pitting initiates within ferrite grains and at phase interface, while reducing the DO can restrain the chemical dissolution of MnS to retard the pit initiation.

Electroactive Shewanella algae accelerates the crevice corrosion of X70 pipeline steel in marine environment

Crevice corrosion causes severe damage to metallic materials in marine environments. The inner mechanism of crevice corrosion in the presence of microbes deserves in-depth investigation. Herein, the electroactive Shewanella algae was found to accelerate the crevice corrosion of X70 pipeline steel through weight loss analysis, electrochemical tests, characterization of surface morphology, and analysis of corrosion products. The corrosion current increased to 2.3 μA cm−2, which was 2.3 folds of that in a sterile medium. Further electrochemical tests were carried out with exogenous addition of riboflavin. It confirmed that extracellular electron transfer accelerated the crevice corrosion in which S. algae participated.

Characterizing pearlite transformation in an API X60 pipeline steel through phase-field modeling and experimental validation

This study explores the microstructural characterization of pearlite phase transformation in high-strength low-alloy API X60 steel, which is used in pipelines. Understanding the formation, phase percentages, and morphology of the pearlitic phase is crucial since it affects the mechanical properties of the considered steel. In this research, a phase-field model, particularly the Cahn–Hilliard approach, was used in order to simulate the formation and morphology of the pearlite phase in response to different heat treatments. Both double- and triple-well potentials were considered for comprehensively studying pearlite’s morphology in the simulations. The simulation results were then compared with experimental outcomes obtained by metallography and field-emission scanning electron microscopy analyses. Considering the double-well potential can help simulate only two phases, ferrite and cementite, which is less compatible with the experiment results than the triple-well potential, which gives the possibility of simulating a three-phase microstructure, ferrite, cementite, and austenite, and a better match with experimental data. The study revealed that as the cooling rate increases, the interlamellar spacing and layer thickness decrease. Additionally, the difference between experimental and simulation results using triple-well potential was approximately ∼10%. Therefore, triple-well potential formulation predictions have better agreements with experimental results for the development circumstance of pearlitic structures.

A comparison of vintage and modern X65 pipeline steel using hollow specimen technique for in-situ hydrogen testing

The transition toward a hydrogen-based economy requires a widespread transport and distribution network, and repurposed natural gas pipelines are a viable option. An assessment of the hydrogen-induced degradation of pipeline steels is needed to inject H2 gas into the existing infrastructure safely. The conservative and standardized method consists of in-situ tensile tests in an autoclave filled with high-pressure hydrogen gas. A proposed alternative method involves using a hollow specimen as containment volume and applying the gas pressure in the inner cavity. This technique has lower costs and shorter test preparation time but is not standardized yet. This study aims to evaluate and compare the tensile properties of API 5L X65 pipeline steel in two states: vintage and modern. The influence of the surface roughness is investigated through parallel tests with drilled and reamed specimens. Hydrogen tests are compared with reference tests in an inert environment. A significant hydrogen-induced decrease in tensile properties is observed, and no significant difference between vintage and modern X65 can be drawn. The reduction in tensile properties is more significant in specimens with higher inner surface roughness. The evaluation of surface conditions appears crucial when assessing the HE susceptibility of hydrogen transport and storage equipment.

Experimental Investigation on Corrosion Behaviour of Heat-Treated API X70 Pipeline Steel

Experimental Investigation on Corrosion Behaviour of Heat-Treated API X70 Pipeline Steel

Safe pipelines for hydrogen transport

The hydrogen compatibility of two X65 pipeline steels for transport of hydrogen gas is investigated through microstructural characterization, hydrogen permeation measurements and fracture mechanical testing. The investigated materials are a quenched and tempered pipeline steel with a fine-grained homogeneously distributed ferrite-bainite microstructure, and hot rolled pipeline steel with a ferrite-pearlite banded microstructure. All tests are performed both under electrochemical and gaseous hydrogen charging conditions. A correlation between electrochemical hydrogen charging and gaseous charging is determined. The results point to inherent differences in the interaction between hydrogen and the two material microstructures. Further research is needed to unveil the influence of material microstructure on hydrogen embrittlement.

Ni-W composite coating reinforced with CrN nanoparticles on X80 pipeline steel: Preparation and characterization

X80 pipeline steel is crucial for oil and gas pipelines. Friction between particulate matter and the inner wall causes abrasive wear during transport, while corrosive environments further degrade the pipeline, leading to leaks. In this study, a nanoscale Ni-W-CrN composite coating was successfully prepared on X80 steel via electrodeposition for protection. The coating's surface morphology, microstructure, and composition were analyzed. The effects of CrN nanoparticle concentration and deposition temperature on the coating's structure, wear, and corrosion resistance were investigated. At 10 g/L CrN and 60°C, the Ni-W-CrN film showed a fine-grained surface with 8.13 wt% CrN, achieving 810 HV microhardness and improving wear and corrosion resistance by 81 % and 89 % compared to Ni-W coatings.

Corrosion Inhibition of X100 Pipeline Steel in 1 M HCl by Two Complexes of Cystine

Corrosion Inhibition of X100 Pipeline Steel in 1 M HCl by Two Complexes of Cystine

Research on the defect depth detection for pipeline steel with double defects using metal magnetic memory method

Metal magnetic memory testing is an effective method to detect the stress state of ferromagnetic materials, and shows great application potential in the field of defect detection of oil and gas pipelines recently. In this paper, the correlation between the normal component of residual magnetic field (RMF) and the defect depth, as well as the applied loading were investigated by tensile tests. The X70 pipeline steels were processed into specimens with double defects of six types of depths and three types of spacings. Some magnetic parameters are defined to characterize the distortion of the RMF in the defect area. The effect of defect depth and applied loading on the magnetic parameters is discussed. The RMF signals measured on the smooth side of the specimens were compared with those on the defective side. Results show that the normal parameters, obtained from the front and back of the specimens, are capable of detecting the defect depth. The slope of the linear relationship between the two increases with the increase of defect spacing. The expressions of normal magnetic parameters were derived based on the Jiles model and magnetic dipole model. The simulation results of defective side and smooth side were compared, as well as the simulation results of different defect spacing. The experimental and numerical simulation results show that the defect depth of pipeline steel can be evaluated by the characteristic parameters of the normal RMF signal under a certain stress level.

Influence of hydrogen volume/specimen surface area ratio on hydrogen embrittlement sensitivity of X52 pipeline steel

In the transition towards green energy, long distance transportation of gaseous hydrogen by pipeline is considered to be an economically attractive solution. For safe transportation of hydrogen, it is important to conduct relevant mechanical tests in representative hydrogen environments and working conditions of pipelines to demonstrate acceptable hydrogen embrittlement resistance of the steel. One important issue is the testing condition for the ratio of gaseous hydrogen volume over specimen surface area required in mechanical testing since this has not been specified in any testing standards and codes or investigated. This study investigated this issue by performing slow strain rate tensile (SSRT) testing of an X52 pipeline steel in gaseous hydrogen with different ratios of hydrogen volume/specimen surface area, Rv/s, ml/mm2. It was found that, with increasing Rv/s ratio, the area reduction of the steel decreased and hydrogen embrittlement sensitivity increased in the range of the Rv/s ratios investigated. The saturating Rv/s ratio appeared to be ∼2.0 beyond which the effect of Rv/s ratio on hydrogen embrittlement sensitivity was relatively small. The macroscopic and microscopic observations on both the fracture and side surfaces of the SSRT tested specimens also found that the tendency to cleavage fracture increased with increasing Rv/s ratio. The results of the ab initio molecular dynamics (AIMD) simulations performed also predicted a dependence of hydrogen embrittlement on hydrogen volume when Rv/s ratio is relatively small.

Effect of Pseudomonas aeruginosa on Corrosion Behavior of X65 Carbon Steel.

X65 pipeline steel is widely used in the field of offshore oil and gas exploitation due to its excellent performance. However, due to the complex environment in the ocean, X65 pipeline steel is faced with a great risk of microbial corrosion failure. Therefore, it is of great significance to study the corrosion mechanism of X65 pipeline steel by microorganisms. In this paper, the corrosion effect of Pseudomonas aeruginosa (P. aeruginosa) secreting phenazine compounds on X65 pipeline steel was studied by the weight loss method, biofilm scanning electron microscopy analysis, surface corrosion morphology observation, electrochemical testing and medium pH test corrosion products. The results showed that the inoculation of P. aeruginosa accelerated the corrosion of X65 steel. After knocking out the phzM and phzS genes that regulate the synthesis of PYO, P. aeruginosa can still produce biofilms on the surface of X65 steel consistent with the morphology of wild-type P. aeruginosa, but the corrosion of X65 steel is significantly reduced. It is proved that PYO plays an important role in the corrosion process of P. aeruginosa on steel.

A Novel Amorphous Alloy Coating for Elevating Corrosion Resistance of X70 Pipeline Steel

A Novel Amorphous Alloy Coating for Elevating Corrosion Resistance of X70 Pipeline Steel

Impact of gravity on biofilm growth and corrosion of X65 pipeline steel by a sulfate reducing bacterium

Desulfovibrio ferrophilus (IS5) corrosion of X65 carbon steel was impacted by gravity. Six o’clock position (6P) had the highest sessile count due to gravity assisting planktonic cell settling in early biofilm formation, leading to most severe static corrosion followed by 9P and 12P. The 7-d weight loss at 6P was 49.6 ± 4.4 mg/cm2 (3.3 mm/a in uniform corrosion rate) followed by 9P with 35.7 ± 2.6 mg/cm2 (2.4 mm/a) and 12P with 20.5 ± 5.5 mg/cm2 (1.4 mm/a). The trend was supported by electrochemical measurements. The weight loss differences reduced considerably when there was agitation, supporting the gravity hypothesis.

Study on the properties of Ni-W-CrN thin films on X80 pipeline steel: Effect of current density and deposition time

X80 pipeline steel, an essential material for oil and gas pipelines, faces challenges in maintaining its integrity due to internal friction and exposure to corrosive environments. Addressing this issue, our study utilized electrodeposition to create a nano Ni-W-CrN composite protective coating on its surface for the first time, enhancing resistance to such wear and corrosion. The results indicate that the film prepared under a current density of 3 A dm−2 and deposition time of 60 min exhibits the finest structure, with a smooth surface, and an average thickness of 35 μm. The microcrystalline size ranges in the 8–15 nm range and the maximum hardness of 813 HV. Under these conditions, the lowest wear rate achieved was 1.16 mm3 (N m)−1. Electrochemical measurements show that the corrosion current density reached a minimum of 6.14 × 10−7 A dm−2, indicating excellent corrosion resistance. Simultaneously, the ratio of microhardness to Young's modulus (H3/E2) reached a maximum of 0.051, indicating the film's optimal resistance to deformation. This provides significant support for the fabrication of high-performance films on the surface of X80 pipeline steel.

Surface morphology of API 5L X65 pipeline steel processed by ultrasonic impact peening: An integrated experimental and computational study

Ultrasonic impact peening (UIP) is a highly effective surface engineering technique to improve material durability through peening-induced surface plastic deformation. These improvements are determined by not only the generation of surface compressive residual stresses but also the alteration of surface morphological features. In literature, researchers have focused primarily on the average roughness (Sa) to understand the morphology changes induced by UIP. From the surface engineering perspective, in addition to Sa, other surface morphological characteristics play key roles in determining material durability, particularly surface skewness (Ssk) and surface kurtosis (Sku), which describe the asymmetrical distribution of surface profiles and the sharpness of peak features, respectively. In this study, surface morphological characteristics of API 5L X65 pipeline steel processed by UIP are investigated with a focus on the effects of processing parameters on Sa, Ssk, and Sku. The results indicate that the optimized UIP conditions lead to the preparation of surfaces with valley structures as the dominant feature accompanied by blunt peaks, resulting in the elimination of stress concentration sites towards enhanced material durability. In addition, surface hardness, residual stresses, and peening-induced deformation depth are measured. Furthermore, to gain a comprehensive understanding of the material response and the underlying mechanisms driving surface morphological alterations by UIP, a finite element method (FEM)-based model is developed. By investigating the effect of process parameters (peening amplitude, peening cycles, and pin size) on the surface deformation depth and stress/strain distribution, a correlation between these process variables with surface characteristics is established.

Coupled slow strain rate and acoustic emission tests for gaseous hydrogen embrittlement assessment of API X65 pipeline steel

Hydrogen embrittlement (HE) sensitivity of API X65 pipeline steel was evaluated in this study through the simultaneous application of slow strain rate tests (SSRT) and acoustic emission (AE) monitoring on hollow dog-bone samples. Exposure to hydrogen gas decreased the elongation to fracture percentage with a significant rise in embrittlement index for the higher pressure of 10 MPa. SEM images of the fracture surfaces demonstrated that the fracture mechanism changed from ductile to ductile–brittle under 1 MPa pressure, and to predominantly brittle with quasi-cleavage characteristic when testing under 10 MPa hydrogen gas. Classification of the AE events based on waveform analysis revealed a mainly shear mode fracture for 10 MPa nitrogen sample, while a dominant tensile mode fracture was identified for the hydrogen charged samples.

Unraveling short-term O2 contamination on under deposit corrosion of X65 pipeline steel in CO2 saturated solution

The impact of short-term O2 contamination on the deposit-covered pipeline steel under a CO2-saturated solution was investigated using steel coupon and wire beam electrode. Results show that the brief exposure to O2 destroyed the FeCO3 film, and converted it into porous iron oxides, weakening its protection property. However, upon CO2 reinjection, the dense FeCO3 film regrew soon underneath the damaged FeCO3 layer on the bare steel, restoring its protective properties. Conversely, the localized corrosion beneath the deposits persisted and worsened, fueled by macro-cell current between the bare steel and the deposit-covered steel.

Investigation of the influence of nano-CrN concentration on the performance of Ni-W coatings in X80 pipeline steel

A novel nano Ni-W-CrN composite coating was developed for X80 pipeline steel to enhance its structural properties and corrosion resistance. The study explored the effects of varying CrN nanoparticle concentrations (0, 5, 10, 15, 20 g/L) in the deposition solution using techniques such as SEM, EDS, and XRD for analysis and an electrochemical workstation for corrosion testing. The optimal CrN concentration was identified at 10 g/L, resulting in a coating with peak hardness (811HV), low friction coefficient (0.16), minimal wear rate (1.18×10−4 mm3·(N·m)−1), and improved corrosion resistance. This coating significantly outperforms Ni-W alloy coatings in hardness, wear resistance, and elastic recovery, offering a promising approach for enhancing the performance of X80 pipeline steel surfaces.

Effect of pre-strain on microstructure evolution and fracture behavior of undermatching X80 pipeline steel girth weld

This work aims to study the effect of pre-strain on the fracture behavior of X80 pipeline girth weld joint, a comprehensive analysis was conducted on the microstructure and mechanical properties of the girth weld before and after pre-strain treatment. The mechanical properties were evaluated through tensile testing, Charpy impact testing, and digital image correlation (DIC) strain analysis. Furthermore, the microstructure and fracture morphology of the girth weld were observed using optical electron microscopy (OM) and scanning electron microscopy (SEM). The results show that the application of pre-strain treatment leads to dislocation accumulation at the grain boundary of X80 pipeline girth weld, resulting in stress concentration and subsequent formation of damage holes. This process disrupts the continuity of chain M-A island and initiates small cracks at the grain boundary, ultimately causing a significant decrease in impact toughness and impact work from 177 J to about 10 J.

Research on Hydrogen-Induced Induced Cracking Sensitivity of X80 Pipeline Steel under Different Heat Treatments.

X80 pipeline steel has played a vital role in oil and gas transportation in recent years. However, hydrogen-related issues frequently lead to pipeline failures during service, resulting in significant losses of properties and lives. Three heat treatment processes (furnace cooling (FC), air cooling (AC), and water cooling (WC)) were carried out to investigate the effect of different microstructures on hydrogen-induced cracking (HIC) susceptibility of X80 pipeline steel. The WC sample demonstrated the highest hydrogen embrittlement index, registering at 21.9%, while the AC and FC samples exhibited progressively lower values of 15.45% and 10.98%, respectively. Under equivalent hydrogen charging durations, crack dimensions with a maximum length exceeding 30 μm in the WC sample generally exceed those in the FC sample and AC sample. The variation is attributed to the difference in microstructures of the samples, predominantly lath bainite (LB) in water-cooled samples, granular bainite (GB) in air-cooled samples, and ferrite/pearlite (F/P) in FC samples. The research results demonstrate that the sensitivity of lath bainite (LB) to HIC is significantly higher than that of pearlite, ferrite, and granular bainite (GB). The presence of a large amount of martensite/austenite (M/A) constituents within bainite results in a multitude of hydrogen trap sites. HIC cracks in bainite generally propagate along the profiles of M/A constituents, showing both intergranular and transgranular cracking modes.