Effect of post-processing annealing treatments on microstructure development and hydrogen embrittlement in API 5L X70 pipeline steel

Ohaeri, Enyinnaya; Omale, Joseph; Rahman, K M Mostafijur; Szpunar, Jerzy A.

doi:10.1016/j.matchar.2020.110124

Cited by 23 publications

(6 citation statements)

References 65 publications

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“…Both these steel grades are considered 'high strength' so one may assume that they are prone to hydrogen embrittlement (HE). However, numerous studies have eluded to the importance of microstructure in the HE process [7,13,30,51,52,57,58]. Yet, no agreement can be found in literature on the role of different microstructural constituents.…”

Section: Location Of Hydrogen In Tsa-coated Steelmentioning

confidence: 99%

Hydrogen in Aluminium-Coated Steels Exposed to Synthetic Seawater

Paul

2020

Surfaces

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Thermally sprayed aluminium (TSA) coatings provide protection to offshore steel structures without the use of external cathodic protection (CP) systems. These coatings provide sacrificial protection in the same way as a galvanic anode, and thus hydrogen embrittlement (HE) becomes a major concern with the use of high strength steels. The effect of TSA on the HE of steel seems to remain largely unknown. Further, the location of hydrogen in TSA-coated steel has not been explored. To address the above knowledge gap, API 5L X80 and AISI 4137 steel coupons, with and without TSA, were prepared and the amount of hydrogen present in these steels when cathodically polarised to −1.1 V (Ag/AgCl) for 30 days in synthetic seawater was determined. One set of TSA-coated specimens was left at open circuit potential (OCP). The study indicates that the amount of hydrogen present in TSA-coated steel is ~100 times more than the amount found in uncoated steel, and that the hydrogen seems to be largely localised in the TSA layer.

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Section: Location Of Hydrogen In Tsa-coated Steelmentioning

confidence: 99%

Hydrogen in Aluminium-Coated Steels Exposed to Synthetic Seawater

Paul

2020

Surfaces

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“…The use of crude oil and natural gas is increasing due to the development of industrial scale. In order to increase the transport efficiency of these raw materials, studies are focusing mainly on the characteristics of high strength, high toughness, and weldability for pipeline materials with large diameter [1][2][3][4][5][6][7]. In particular, the demand for relatively inexpensive natural gas is gradually increasing due to the rise in oil prices, and transportation through natural gas pipelines from Russia to E.U.…”

Section: Introductionmentioning

confidence: 99%

“…API (American Petroleum Institute) steel is a type of high strength low alloy (HSLA) steel, and X70 refers to a steel with a minimum yield strength of 70 ksi class, and is mainly used as a structural material for linepipe steel for natural gas [3][4][5][6][7]. However, as the material strength of API steel increases, hydrogen embrittlement is more likely to occur due to the trace amount of hydrogen remaining.…”

Section: Introductionmentioning

confidence: 99%

“…The trapping of diffusible hydrogen becomes activated with an increase of dislocation density in softened HAZ (heat affected zone), leading to premature rupture which initiated from hydrogenpromoted voids with enhanced plasticity [2]. As the tensile strength increases, the risk of brittle fracture increases, so it is necessary to reduce the strength and hardness using heat treatment [5]. Hydrogen trapping density and hydrogen diffusion coefficient is depending on the microstructual constituents [4], and if there are non-metallic inclusions exist at the tip of the crack, the ductile fracture transited to the brittle fracture [6].…”

Section: Introductionmentioning

confidence: 99%

“…Researchers have studied the hydrogen embrittlement of API linepipe steel and a test method to investigate the hydrogen embrittlement behavior [8][9][10][11][12][13], and also there are several research data on the effect of hydrogen content on the fracture behavior of API X70 steel [4][5][6][7][8][9][14][15][16][17]. In South Korea, POSCO (Pohang Steel Company) and Dongkuk Steel produce a certain amount of API X70 steel, but a few research papers on hydrogen embrittlement of API X70 steel using electrochemical hydrogen charging method were published worldwide [15,17].…”

Section: Introductionmentioning

confidence: 99%

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Effect of Electrochemical Hydrogen Charging Time on Hydrogen Embrittlement of the Hot-Rolled and Accelerated Cooling Treated API X70 Steel

Baek

Nahm

2021

Met. Mater. Int.

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This study investigated the effect of the hydrogen charging time on the hydrogen embrittlement of hot-rolled and acceleratedcooling treated API X70 steel by using the electrochemical hydrogen charging method. Tensile and V-notch Charpy impact test were completed for the specimens of hydrogen charged for 0, 2, 4, and 10 h, and then microstructural observation were performed. The tensile and yield strength tended to decrease slightly and the total elongation started to decrease rapidly up to 2 h charging time and then these gradually decreased with the hydrogen charging time. The post-uniform elongation increased slightly after the holding time of 2 h due to the occurrence of two-step stress reduction phenomenon and its mechanism has suggested. The effect of the hydrogen embrittlement on impact absorption energy according to the hydrogen charging time were also investigated. The fracture surface of the hydrogen charged ones are generally composed of cleavage fracture surfaces. It was demonstrated that the external cracks were formed on the outside of tensile tested specimen and the external shape of the fracture portion was fractured without large elongation at hydrogen charged specimens.

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Investigation on Hydrogen Embrittlement Sensitivity of Hot-Rolled and Annealed Microstructure to AISI 430 Ferritic Stainless Steel

Wang

Xiao

et al. 2021

J. of Materi Eng and Perform

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This paper studied the influence of hot rolling and annealing processes on the hydrogen embrittlement sensitivity of AISI 430 ferritic stainless steel and the changes in hydrogen-induced fracture modes through electrochemical hydrogen charging experiments. The tensile test results show that the hot-rolled specimen has the highest hydrogen embrittlement sensitivity, and the highest yield strength and tensile strength. After the heat treatment, the yield strength of all specimens was significantly increased after hydrogen charging, which was attributed to the hydrogen-induced dislocation pinning effect. The fracture morphology analysis revealed that the hot-rolled specimen was dominated by intergranular fracture, accompanied by cleavage fracture, predominantly by the hydrogen-enhanced decohesion (HEDE) mechanism, while the fracture modes of annealed specimen were cleavage fracture and quasi-cleavage fracture due to the hydrogenenhanced localized plasticity (HELP) and hydrogen-enhanced decohesion (HEDE) mechanisms.

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Effect of post-processing annealing treatments on microstructure development and hydrogen embrittlement in API 5L X70 pipeline steel

Cited by 23 publications

References 65 publications

Hydrogen in Aluminium-Coated Steels Exposed to Synthetic Seawater

Hydrogen in Aluminium-Coated Steels Exposed to Synthetic Seawater

Effect of Electrochemical Hydrogen Charging Time on Hydrogen Embrittlement of the Hot-Rolled and Accelerated Cooling Treated API X70 Steel

Investigation on Hydrogen Embrittlement Sensitivity of Hot-Rolled and Annealed Microstructure to AISI 430 Ferritic Stainless Steel

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