Influence of sulphur content and inclusion distribution on the hydrogen induced blister cracking in pressure vessel and pipeline steels

Domizzi, G.; Anteri, G.; Ovejero-Garcı́a, J.

doi:10.1016/s0010-938x(00)00084-6

Cited by 182 publications

(69 citation statements)

References 2 publications

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“…As the grain size decreases, although the mobility of hydrogen increases because of larger grain boundary area per unit volume, the higher density of nodes or junction points can act as potential traps for hydrogen atoms and lead to a reduction in its mobility. As a result of these two opposing effects, the hydrogen diffusion coefficient will be a maximum at an optimum grain size, as pointed out by Ichimura [11]. However, these authors have also reported that, for samples with smaller grain sizes the trapping effect of hydrogen at grain boundary nodes is significantly higher.…”

Section: Effect Of Grain Sizementioning

confidence: 85%

“…(4b) that the distribution of the aspect ratios of MnS precipitates for the MX70 specimen has an extremely long tail with some MnS precipitates exhibiting very high aspect ratios of up to 20:1. Domizzi et al [11]have reported that the presence of even a small number of very elongated inclusions can result in reduced HIC resistance. So this factor could contribute to the lower HIC resistance of the MX70 steel.…”

Section: Effect Of Precipitatesmentioning

confidence: 99%

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Effect of manganese content and microstructure on the susceptibility of X70 pipeline steel to hydrogen cracking

Hejazi

Haq

Yazdipour

et al. 2012

Materials Science and Engineering: A

118

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The influence of composition and microstructure on susceptibility to hydrogen induced cracking (HIC) was investigated in high strength pipeline steels, with Mn contents of 1.2% (standard, X70), and 0.5% (medium, MX70). The HIC resistance of the simulated coarse grained heat affected zone microstructures and normalized X70 transfer bar was also investigated. Notched and fatigue pre-cracked samples were charged with hydrogen prior to three point bend tests. The conditional fracture toughness JQ was determined. The results are discussed in relation to grain size, microstructure, composition and the type and distribution of non-metallic inclusions and precipitates. Published as "Effect of manganese content and microstructure on the susceptibility of X70 pipeline steel to hydrogen cracking" AbstractHydrogen, even in very low concentrations, can diffuse to regions of high stress concentration resulting in a degradation of mechanical properties. However, the transport of hydrogen depends on the interaction between hydrogen atoms and microstructural traps which, in turn, is related to microstructure. The influence of composition and microstructure on susceptibility to hydrogen embrittlement was investigated by selecting pipeline steels with different Mn contents, i.e., standard Mn (X70) and medium Mn (MX70) strips. The HAZ (heat affected zone) microstructures of these strips as well as a normlised transfer bar (TB) were also investigated. HAZ simulations were conducted using Gleeble thermo-mechanical machine to simulate a thermal cycle typical of inservice repairs. Notched and fatigue pre-cracked samples were subjected to electrochemical hydrogen charging using a solution of H 2 SO 4 and NaAsO 2 to achieve 2 and 4 ppm hydrogen content. Three point bend tests were conducted on as-received and hydrogen-charged samples. The X70 strip exhibited a higher J Q than the MX70 strip before and after charging, whereas the TB displayed the lowest J Q . The fracture performance of both steels deteriorated almost linearly with an increase in the hydrogen content. Because of their coarser prior austenite grain sizes and the presence of relatively hard bainitic-ferrite structure with martensite/austenite islands, the simulated HAZ microstructures of the two steels demonstrated significantly lower fracture resistance both with and without hydrogen. The results obtained were compared and discussed in relation to the grain size, microstructure, composition and the type and distribution of precipitates in the samples.

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Section: Effect Of Grain Sizementioning

confidence: 85%

Section: Effect Of Precipitatesmentioning

confidence: 99%

Effect of manganese content and microstructure on the susceptibility of X70 pipeline steel to hydrogen cracking

Hejazi

Haq

Yazdipour

et al. 2012

Materials Science and Engineering: A

118

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“…MnS has good deformability and is easy to extend along the rolling direction in the rolling process, which causes anisotropy and significantly decreases the transverse properties of the material [5], and these elongated MnS inclusions are ready sources of cracks and expansion channels in slab steel, thus reduce the life of the material [6]. In order to suppress such harmful effects, it is helpful to form hard inclusions which are difficult to deform by adding an appropriate amount alloying elements, like Ca, Ti, Mg, RE and so on.…”

Section: Overview Of Sulfide In Sulfur-based Free-cutting Steelmentioning

confidence: 99%

“…The size, shape and distribution of MnS have a significant impact on the performance of the resulting steel. MnS can suppress the grain growth and promote the precipitation of intragranular ferrite, by improving w(Mn)/w(S) to generate more MnS while decreasing the generation of FeS, which has a low melting point, thus finally improving the high temperature ductility of the steel [4].MnS has good deformability and is easy to extend along the rolling direction in the rolling process, which causes anisotropy and significantly decreases the transverse properties of the material [5], and these elongated MnS inclusions are ready sources of cracks and expansion channels in slab steel, thus reduce the life of the material [6]. In order to suppress such harmful effects, it is helpful to form hard inclusions which are difficult to deform by adding an appropriate amount alloying elements, like Ca, Ti, Mg, RE and so on.…”

mentioning

confidence: 99%

Key Elements of Sulfide Modification in the Sulfur-based Free-cutting Steel

Li¹,

Huang²,

An³

et al. 2017

Proceedings of the 2017 2nd International Symposium on Advances in Electrical, Electronics and Computer Engineering (ISAEECE 20

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Sulfides are beneficial inclusion in free-cutting steel, and can cause chips to break easily as an internal source of stress concentration when cutting steel, and also lubricate the tool and workpiece, thus reducing tool wear and improving machinability. Sulfide morphology directly determines the performance of the free-cutting steel, and it is possible to improve the machinability of the free-cutting steel by changing the MnS inclusions into small, dispersive, spherical or spindle-shaped inclusions, thus making them difficult to deform. In aluminum-killed steel treated with Ca or Mg, there are numerous small and dispersive complex inclusions with an oxide core (CaO· Al2O3 or MgO· Al2O3) and a sulfide surface layer ((Mn,Ca)S or (Mn,Mg)S). Mg can form simple oxides like MgO, MgS or Mg-O-S. Mg can also form complex inclusions with an oxide core (MgO) and sulfide surface layer (MnS or Mn-Mg-S). Overview of Sulfide in Sulfur-based Free-cutting SteelThe sulfide in sulfur-based free-cutting steel usually exists as (FeMn)S[1]. MnS are beneficial inclusions which can cause chips to be easily broken as an internal source of stress concentration when cutting steel, and can also lubricate the tool and workpiece and reduce tool wear, thus improving machinability [2,3]. MnS is one of the most common plastic nonmetallic inclusions in free-cutting steel, and is commonly used to improve machinability. The size, shape and distribution of MnS have a significant impact on the performance of the resulting steel. MnS can suppress the grain growth and promote the precipitation of intragranular ferrite, by improving w(Mn)/w(S) to generate more MnS while decreasing the generation of FeS, which has a low melting point, thus finally improving the high temperature ductility of the steel [4].MnS has good deformability and is easy to extend along the rolling direction in the rolling process, which causes anisotropy and significantly decreases the transverse properties of the material [5], and these elongated MnS inclusions are ready sources of cracks and expansion channels in slab steel, thus reduce the life of the material [6]. In order to suppress such harmful effects, it is helpful to form hard inclusions which are difficult to deform by adding an appropriate amount alloying elements, like Ca, Ti, Mg, RE and so on. These hard inclusions distribute around the MnS and suppress its deformation, and make the MnS spindle-shaped or spherical (L /W≤3). Such inclusions deform less during hot processing, and this steel has good machinability. Modification Mechanism and Route of Ca on SulfidesCa is the currently most widely used alloying element to modify sulfides. The works of Averin [7], Lou [8], and Jiang et al. [9] have shown that Ca can partially transform MnS into CaS, and they can form a solid solution with each other to generate a new phase of (Mn,Ca)S. The hardness of (Mn,Ca)S is relatively high and the ductility is relatively low, and thus it can improve the transverse impact

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“…Por esta razão, é necessário o controle do teor de enxofre para níveis bem baixos, menores que 0,002%, para se evitar a formação de inclusões alongadas de sulfeto de manganês (MnS), que são locais preferenciais para iniciação de trincas (Domizzi;Anteri;Overejo-Garcia, 2001). O controle da composição química dos aços tem como objetivo proporcionar maior homogeneidade microestrutural e melhorar as propriedades mecânicas da liga metálica.…”

Section: Enxofre (S)unclassified

Comportamento De Aço Estrutural Api 5l X65 Após Exposição Ao Hidrogênio: Uma Abordagem Baseada Na Fratura Dúctil

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Influence of sulphur content and inclusion distribution on the hydrogen induced blister cracking in pressure vessel and pipeline steels

Cited by 182 publications

References 2 publications

Effect of manganese content and microstructure on the susceptibility of X70 pipeline steel to hydrogen cracking

Effect of manganese content and microstructure on the susceptibility of X70 pipeline steel to hydrogen cracking

Key Elements of Sulfide Modification in the Sulfur-based Free-cutting Steel

Comportamento De Aço Estrutural Api 5l X65 Após Exposição Ao Hidrogênio: Uma Abordagem Baseada Na Fratura Dúctil

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