Microstructure and Strengthening/Toughening Mechanisms of Heavy Gauge Pipeline Steel Processed by Ultrafast Cooling

Xue-qiang, Wang; Yuan, Guo; Zhao, Junpeng; Wang, Guodong

doi:10.3390/met10101323

Cited by 12 publications

(7 citation statements)

References 17 publications

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“…(Figure 1a,b, respectively), the X70 steel is composed of globular ferrite grains with grain boundary pearlite grains and coarse dispersion of precipitates, while the X100 steel is made up of bainitic ferrite grains with finely dispersed austenite grains. This is consistent with the literature [27][28][29][30]. The micrographs were obtained by polishing the ground surfaces using a 1 µm diamond suspension to obtain a mirror surface finish and then etched with a 2% nital solution for 15 to 25 s. The chemical compositions of the carbon steels as received from the manufacturers are presented in Table 1.…”

Section: Experimental Procedures 21 Exposed Materialssupporting

confidence: 79%

Effect of Dissolved CO2 on the Interaction of Stress and Corrosion for Pipeline Carbon Steels in Simulated Marine Environments

Abubakar

Mori

Sumner

2023

Metals

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Offshore pipelines are subjected to stresses (e.g., from fluid flow, mechanical vibration, and earth movement). These stresses, combined with corrosive environments and in the presence of trace gases (O2, CO2), can increase the pipeline’s corrosion rate and potentially lead to cracking. As such, the impact of trace gases such as CO2 (linked to enhanced oil recovery and carbon capture and sequestration) on corrosion is key to determining whether pipelines are at increased risk. American Petroleum Institute (API) 5L X70 and X100 were exposed as stressed C-rings (80% or 95 % of yield strength). The tests were conducted with either N2 (control) or CO2 bubbled through 3.5% NaCl, at either 5 °C or 25 °C. Linear polarization resistance was used to assess corrosion rate, while morphology and variation were determined using optical microscopy (generating metal loss distributions) and scanning electron microscopy. The control experiment (N2) showed that corrosion rates correlated with temperature and stress. In this low O2 environment, both alloys showed similar trends. Under CO2 exposure, all samples showed accelerated corrosion rates; furthermore, the morphologies generated were different for the two alloys: undercutting corrosion with discontinuous microcracks (X70) or deep, wide ellipses (X100). Understanding these changes in corrosion response is key when selecting materials for specific operational environments.

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Section: Experimental Procedures 21 Exposed Materialssupporting

confidence: 79%

Effect of Dissolved CO2 on the Interaction of Stress and Corrosion for Pipeline Carbon Steels in Simulated Marine Environments

Abubakar

Mori

Sumner

2023

Metals

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“…Additionally, the microstructures of the HAZ differ between the two processes, as evidenced in Figure 3 and Figure 4 . For GMAW, the rapid cooling conditions lead to the formation of smaller bainitic laths and dispersed precipitation of micro-alloyed carbon and nitride compounds, which enhance the mechanical properties [ 44 , 45 ]. Moreover, the faster cooling rate contributes to a finer grain size in the HAZ, thereby improving strength and hardness [ 46 , 47 ].…”

Section: Resultsmentioning

confidence: 99%

Inhomogeneous Strain Behaviors of the High Strength Pipeline Girth Weld under Longitudinal Loading

Zhang,

Ma,

Liu

et al. 2024

Materials

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Unforeseen failures in girth welds present a significant challenge for the pipeline industry. This study utilizes 3D Digital Image Correlation (DIC) assisted cross-weld tensile testing to analyze the strain response of high-strength thick-walled pipelines, providing essential insights into the strain migration and fracture mechanisms specific to girth welds. The results reveal that the welding process significantly affects the mechanical distribution within the girth weld. The tested Shielded Metal Arc Welded (SMAW-ed) pipe exhibited undermatched girth welds due to high heat input, while Gas Metal Arc Welding (GMAW) introduced a narrower weld and Heat-Affected Zone (HAZ) with higher hardness than the base metal, indicative of overmatched girth welds. Strain migration, resulting from a combination of metallurgical heterogeneous materials and geometrical reinforcement strengthening, progressed from the softer HAZ to the base metal in the SMAW-ed sample with reinforcement, ultimately leading to fracture in the base metal. In contrast, the GMAW-ed sample shows no strain migration. Reinforcement significantly improves the tensile strength of girth welds and effectively prevents failure in the weld region. Sufficient reinforcement is crucial for minimizing the risk of failure in critical areas such as the weld metal and HAZ, particularly in SMAW-ed pipes.

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“…It should be mentioned that σtssc / σ min 0.2 ratio is not standardized; nevertheless the ratio is that common criterion of steel serviceability in the hydrogen sulfide containing environment. If its value excesses 0.8 then the material is considered as a serviceable one [15].…”

Section: Methodsmentioning

confidence: 99%

Analysis of corrosion fatigue steel strength of pump rods for oil wells

Vynnykov¹,

Kharchenko²,

Manhura³

et al. 2022

Min. miner. depos.

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Purpose is to perform analysis of corrosion durability (fatigue) of pump rod materials in terms of various chemically active simulation environments, and study influence of economically modified rare-earth impurity on corrosion fatigue strength of pump rod materials. Methods. 40 and 20N2M steel grades have been applied as well as experimental steel (ES). Steel of the conditinal ES grade has been melted within a pilot site of Institute of Electric Welding Named after E.O. Paton of the National Academy of Sciences of Ukraine. The steel was alloyed economically by means of a micro impurity of a rare-earth element (REE) being 0.03% of cerium; in addition, it contained comparatively low concentration of sulfur and phosphorus as well as minor concentration of dissolved hydrogen. The following has been used as simulation environments: 1) NACE environment (i.e. 5% NaCl solution which contained 0.5% СН3СООН, and saturated H2S; t = 22 ± 2°C; pH = 3.8-4.0); 2) 3% NaCl solution without hydrogen sulphide. Once every day, the environment was replaced to oxygenate it up to 8-10 mg/l concentration. Findings. Stability against sulfide stress-corrosion cracking (SSCC), hydrogen initiated cracking (HIC), and corrosion fatigue of steel of deep pump rods for oil industry has been studied. It has been defined that the experimental steel, modified economically by means of micro impurities of a REE, meets NACE MR0175-96 standard in terms of chemical composition as well as strength; in turn, 20N2M and 40 steel grades have high resistance neither to SSCC (threshold stresses are < 0.8 s) nor to corrosion fatigue attack; moreover, steel grade 40 has demonstrated low resistance to HIC (CLR > 6% and CTR > 3%). Originality. It has been identified that corrosion fatigue attack results from hydrogen penetration of steel initiating its cracking and hence destruction under the effect of alternating loads accelerated by the action of corrosive environment. Further, surface micro destructions, influenced by micro stresses, transform into large discontinuities and cracks with following macro destructions. Practical implications. It has been proved that high resistance to corrosion cracking can be achieved by means of refining of pump-rod steel of ferrite and perlite type using metallurgical methods, i.e. 0.01-0.03% REE microalloying.

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Microstructure and Strengthening/Toughening Mechanisms of Heavy Gauge Pipeline Steel Processed by Ultrafast Cooling

Cited by 12 publications

References 17 publications

Effect of Dissolved CO2 on the Interaction of Stress and Corrosion for Pipeline Carbon Steels in Simulated Marine Environments

Effect of Dissolved CO2 on the Interaction of Stress and Corrosion for Pipeline Carbon Steels in Simulated Marine Environments

Inhomogeneous Strain Behaviors of the High Strength Pipeline Girth Weld under Longitudinal Loading

Analysis of corrosion fatigue steel strength of pump rods for oil wells

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