Subsea

2 cases · 34 images

Crevice Corrosion in a Subsea System — Aspect Before Analysis

Microstructure: Segregation Bands Capture method: Optical Microscope clear all

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Longitudinal section micrography in a position of the thread, far from the failure. The stud presented a quenching and tempering structure and the thread was machined.
84
VIEW
ML00136 / Jun.2018
Hydrogen Cracks of Subsea Studs
M - Low Alloy Medium Carbon QTP - FastenerAp - SubseaCd - Hydrogen Embrittlement
Cm - Nital Etched Micrography by OMDf - Machined Thread
Micrography of a longitudinal section of the bolt, as polished, presenting brittle cracks, transverse to the bolt axis.
1241
VIEW
ML00077 / Jun.2018
Hydrogen Cracking of LAS Subsea Bolts
M - Low Alloy Medium Carbon QTP - FastenerAp - SubseaCd - Hydrogen Embrittlement
Cm - Micrography by OMDf - Cracks

More from these cases

ML00136 — Hydrogen Cracks of Subsea StudsM - Low Alloy Medium Carbon QTP - FastenerAp - SubseaCd - Hydrogen Embrittlement
Microstructure of the stud in the longitudinal section, presenting segregated bands, not uniformly distributed in the section. The bands are associated to elongated and aligned inclusions, and a refined microstructure, probably due to carbon and alloying elements concentration.
69
VIEW
ML00136 / Jun.2018
Hydrogen Cracks of Subsea Studs
M - Low Alloy Medium Carbon QTP - FastenerAp - SubseaCd - Hydrogen Embrittlement
Cm - Nital Etched Micrography by OMDf - Banded Structure
Microstructure of the stud in the longitudinal section, out of a region of segregation, where the tempered martensitic microstructure appears more uniform.
72
VIEW
ML00136 / Jun.2018
Hydrogen Cracks of Subsea Studs
M - Low Alloy Medium Carbon QTP - FastenerAp - SubseaCd - Hydrogen Embrittlement
Cm - Nital Etched Micrography by OMDf - Martensite
Micrographic detail of the segregated bands, not uniformly distributed in the section. The bands are associated to elongated and aligned inclusions, and a refined microstructure, probably due to carbon and alloying elements concentration. The localized microhardness (50g) in the band showed levels about 540HV, and out of the band, in the same localtion, presented an average hardness of 321 HV, indicating that the material is non uniform in the regions where there are bands.
66
VIEW
ML00136 / Jun.2018
Hydrogen Cracks of Subsea Studs
M - Low Alloy Medium Carbon QTP - FastenerAp - SubseaCd - Hydrogen Embrittlement
Cm - Nital Etched Micrography by OMDf - Banded Structure
Micrographic detail of the martensitic structure of the stud in the longitudinal section, out of a region of segregation, where the microstructure appears more uniform and the microhardness is about 370HV (50g).
62
VIEW
ML00136 / Jun.2018
Hydrogen Cracks of Subsea Studs
M - Low Alloy Medium Carbon QTP - FastenerAp - SubseaCd - Hydrogen Embrittlement
Cm - Nital Etched Micrography by OMDf - Martensite
Low magnification micrography of a stud longitudinal section in the first thread fillet adjacent to the fracture, presenting a large secondary crack without any deformation evidence. This reveals a brittle material behavior, although the hardness measured at the stud end revealed 33HRc, as should be expected by the material specification.
47
VIEW
ML00136 / Jun.2018
Hydrogen Cracks of Subsea Studs
M - Low Alloy Medium Carbon QTP - FastenerAp - SubseaCd - Hydrogen Embrittlement
Cm - Nital Etched Micrography by OMDf - Secondary Cracks

+17 more from this case →

ML00077 — Hydrogen Cracking of LAS Subsea BoltsM - Low Alloy Medium Carbon QTP - FastenerAp - SubseaCd - Hydrogen Embrittlement
Multiple intergranular cracks transverse to the bolt axis. Hydrogen assisted cracking due to cathodic protection of a high strenght steel. Micrography in the "as polished" condition.
104
VIEW
ML00077 / Jun.2018
Hydrogen Cracking of LAS Subsea Bolts
M - Low Alloy Medium Carbon QTP - FastenerAp - SubseaCd - Hydrogen Embrittlement
Cm - Micrography by OMDf - Brittle Cracks
Micrography of a longitudinal section of the bolt, as polished, presenting brittle Intergranular and transgranular cracks, transverse to the bolt axis.
94
VIEW
ML00077 / Jun.2018
Hydrogen Cracking of LAS Subsea Bolts
M - Low Alloy Medium Carbon QTP - FastenerAp - SubseaCd - Hydrogen Embrittlement
Cm - Micrography by OMDf - Longitudinal Section
Micrography of a longitudinal section of the bolt, showing the (secondary) crack propagating, transverse to the bolt, from a thread fillet.
91
VIEW
ML00077 / Jun.2018
Hydrogen Cracking of LAS Subsea Bolts
M - Low Alloy Medium Carbon QTP - FastenerAp - SubseaCd - Hydrogen Embrittlement
Cm - Nital Etched Micrography by OMDf - Longitudinal Section
Micrographic detail of the (secondary) crack propagating transverse to the bolt, from a thread fillet.
91
VIEW
ML00077 / Jun.2018
Hydrogen Cracking of LAS Subsea Bolts
M - Low Alloy Medium Carbon QTP - FastenerAp - SubseaCd - Hydrogen Embrittlement
Cm - Nital Etched Micrography by OMDf - Longitudinal Section
Micrographic detail of the (secondary) crack propagating transverse to the bolt, from a thread fillet.
80
VIEW
ML00077 / Jun.2018
Hydrogen Cracking of LAS Subsea Bolts
M - Low Alloy Medium Carbon QTP - FastenerAp - SubseaCd - Hydrogen Embrittlement
Cm - Nital Etched Micrography by OMDf - Longitudinal Section

+5 more from this case →