Effective Process Design for the Production of HIC-Resistant Linepipe Steels

Nieto, J.; Elias, Thierry; López, Graciela; Campos, Guadalupe do Nascimento; López, Francisco Javier; Garcı́a, R.; De, A. K.

doi:10.1007/s11665-013-0544-9

Cited by 12 publications

(3 citation statements)

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“…Accordingly, considerable efforts have been made to develop the steel used as pressure vessel facilities with superior resistance to HAC [ 7 , 8 , 9 , 10 ]. For this purpose, a variety of technical solutions, such as de-phospho/sulfu-rization of molten steel [ 11 , 12 ], Ca-treatment [ 13 ], cast steel soft reduction [ 14 ], and thermal mechanical controlled process (TMCP) [ 15 , 16 , 17 ], have been proposed. Microstructural modifications by reducing the number of second phases, such as retained austenite (RA), martensite-austenite constituents (MA), and other hard phases, and their role in improving the HAC resistance, have been reported [ 18 , 19 ].…”

Section: Introductionmentioning

confidence: 99%

Effects of Alloying Elements (C, Mo) on Hydrogen Assisted Cracking Behaviors of A516-65 Steels in Sour Environments

et al. 2020

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This study examined the effects of alloying elements (C, Mo) on hydrogen-induced cracking (HIC) and sulfide stress cracking (SSC) behaviors of A516-65 grade pressure vessel steel in sour environments. A range of experimental and analytical methods of HIC, SSC, electrochemical permeation, and immersion experiments were used. The steel with a higher C content had a larger fraction of banded pearlite, which acted as a reversible trap for hydrogen, and slower diffusion kinetics of hydrogen was obtained. In addition, a higher hardness in the mid-thickness regions of the steel, due to center segregation, resulted in easier HIC propagation. On the other hand, the steel with a higher Mo content showed more dispersed banded pearlite and a larger amount of irreversibly trapped hydrogen. Nevertheless, the addition of Mo to the steel can deteriorate the surface properties through localized pitting and the local detachment of corrosion products with uneven interfaces, increasing the vulnerability to SSC. The mechanistic reasons for the results are discussed, and a desirable alloy design for ensuring an enhanced resistance to hydrogen assisted cracking (HAC) is proposed.

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Section: Introductionmentioning

confidence: 99%

Effects of Alloying Elements (C, Mo) on Hydrogen Assisted Cracking Behaviors of A516-65 Steels in Sour Environments

et al. 2020

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“…As inclusões não metálicas, principalmente as de MnS que apresentam formato alongado, consistem em um dos mais perigosos tipos de sítio de aprisionamento de H. De acordo com os autores [27] a trinca apresentada pela Figura 13 teve início na interface martensita/MnS e se propagou ao longo da região segregada.…”

Section: Inclusõesunclassified

“…ao bandeamento da microestrutura, a microconstituintes de dureza mais elevada e a cavidades (ou microcavidades) de encolhimento, também conhecidas como rechuoes[27] (mesma natureza das microcavidades formadas próximas às interfaces inclusão/matriz).Por último, porém não menos importante, a segregação é responsável pela formação de poros (cavidades) de encolhimento na linha central dos aços durante o lingotamento contínuo. Quando H em excesso se acumula nestas cavidades, a sua aniquilação durante o processamento a quente é dificultada; os átomos de H se recombinam formando moléculas de H 2 e, quando a pressão é alta o bastante, ocorre o trincamento na linha central[7,27]. Além de serem consideradas traps não saturáveis[59], as cavidades podem ser classificadas como traps irreversíveis.…”

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Efeito de características microestruturais na difusividade do hidrogênio em dois aços grau API X65.

Pereira¹

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High strength low alloy steels are widely applied as pipelines for crude oil and natural gas transportation and, currently, new approaches to alloy design, in addition to the use of advanced steelmaking and processing techniques, have become essential for obtaining structures that resist to hydrogen damage, which is the main cause of pipelines failure in H 2 Srich environments. The main objective of the present work is to evaluate the influence of microstructural features on hydrogen diffusivity in two API X65 steels, with different Mn contents. One of the steel plates has been recently developed for usage in sour environments, is on its experimental stage and has a low Mn content. The other one is a commercial plate steel, with high Mn content, developed for sweet applications. Both steel plates were characterized in its three sections, in relation to the rolling direction: longitudinal, transverse and top surface of the plate (parallell to the rolling direction). After that, samples obtained from each section of the plates were submitted to hydrogen permeation tests; the low Mn steel was also analysed with EBSD, for texture determination. The low Mn steel presents a homogeneous microstructure through plate thickness, composed of refined ferrite and small pearlite islands. The high Mn steel has a heterogeneous microstructure through the plate thickness, composed of ferrite and pearlite bands, and presents centerline segregation. Hydrogen permeation tests showed that the D eff obtained for the low Mn steel sections are slightly higher than for the high Mn steel. Another two important parameters that were calculated for both steels are the subsurface hydrogen concentration, C 0 , and the number of traps per unit volume, N t. Contrary to what was expected, the low Mn steel presented the higher C 0 and N t values. Thermal dessorption spectroscopy analysis confirmed that the low Mn steel traps more H atoms than the high Mn one. These results, along with the similar D eff values, were related to the presence of nanoprecipitates of microalloying elements, that cannot be detected via optical and scanning electron microscopy. Additionally, also for both steels, the D eff values varied in function of the analyzed section as it follows: D eff longitudinal ≅ D eff transverse > D eff top. In order to better understand this anisotropic behavior, a new diffusion coefficient, which was called diffusion coefficient at the steady state, D ss , was determined. D ss considers that all the trapping sites are saturated, enabling, thus, the evaluation of physical obstacles to H diffusion. For the high Mn steel, the D ss varied in the same matter as the D eff : D ss longitudinal ≅ D ss transverse > D ss top; this behavior was associated with the microstructural banding present in the material. For the low Mn steel, the D ss exhibited a different behavior: D ss transverse > D ss longitudinal ≥ D ss top, suggesting that H diffusion can be aided by grain boundaries while the trapping sites are being filled and that crystallographic textur...

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Improved Resistance to Hydrogen-Induced Cracking by Tempering of Intercritically Rolled Accelerated-Cooled X65 Steel

O’Brien

Lucon

Huey

et al. 2023

Metall Mater Trans A

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Effective Process Design for the Production of HIC-Resistant Linepipe Steels

Cited by 12 publications

References 3 publications

Effects of Alloying Elements (C, Mo) on Hydrogen Assisted Cracking Behaviors of A516-65 Steels in Sour Environments

Effects of Alloying Elements (C, Mo) on Hydrogen Assisted Cracking Behaviors of A516-65 Steels in Sour Environments

Efeito de características microestruturais na difusividade do hidrogênio em dois aços grau API X65.

Improved Resistance to Hydrogen-Induced Cracking by Tempering of Intercritically Rolled Accelerated-Cooled X65 Steel

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