A

6 cases · 12 images

Crevice Corrosion in a Subsea System — Aspect Before Analysis

Condition: Damage Capture method: Optical Microscope Detail focus: Crack clear all

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Low magnification micrography of another thread fillet, presenting secondary cracks from the bottom of the thread, not yet opened.
45
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 - Crack
Micrography of a longitudinal section, at the fillet that was tightened (to the end of the bolt) adjacent to the fracture. The cracking is typical of localized overloading, probably because it was only partially tightened in the tapped hole.
104
VIEW
ML00130 / Jun.2018
Fatigue Fracture of Overloaded Bolts
M - Low Alloy Medium Carbon QTP - FastenerAp - O&G Well DrillingCd - Mechanical Fatigue
Cm - Nital Etched Micrography by OMDf - Crack
The longitudinal section of the fitting at the thread shows plastic deformation of the fillets, and a crack at the bottom of the thread.
56
VIEW
ML00103 / Nov.2017
Brittle Fracture of a Free-Cutting Connector
M - Low Carbon SteelP - Machined PartAp - ShipCd - Brittle Fracture
Cm - Nital Etched Micrography by OMDf - Crack
Micrographic detail of the forging lap defect that appears at the nut surface like a crack, filled with oxides. The nut presented a martensitic structure in the center of the nut, but in the regions adjacent to the defect the structure is ferritic-bainitic due to decarburization. There are several globular oxides (grey spots) that became entrapped during the forging.
654
VIEW
ML00099 / Jan.2018
Forging Defect in a Cadmium Plated Nut
M - Medium Carbon SteelP - NutAp - PipingCd - Fabrication Defect
Cm - Nital Etched Micrography by OMDf - Crack
Detail of the fusion line region of the repair weld. Cracks filled with oxides indicating that the material was already corroded when the bead was deposited.
105
VIEW
ML00015 / Oct.2017
Intergranular Corrosion of 304SS Plate
M - Austenitic Stainless SteelP - Rolled PlateAp - RefineryCd - Intergranular Corrosion
Cm - Micrography by OM using A262 Method ADf - Crack
Micrography of a longitudinal section of a CrMov steel bolt that broke in service by a creep mechanism in a gas turbine. Tempered structure. Interconnected cracks paralled to the fracture surface.
95
VIEW
ML00004 / Jun.2018
Creep in High Temperature Bolts
M - CrMo SteelP - FastenerAp - Gas TurbineCd - Creep
Cm - Nital Etched Micrography by OMDf - Crack

More from these cases

ML00136 — Hydrogen Cracks of Subsea StudsM - Low Alloy Medium Carbon QTP - FastenerAp - SubseaCd - Hydrogen Embrittlement
As polished micrographical detail of the cracks at the bottom of the thread fillet. There are several small cracks some of them associated to longitudinal inclusions. There are some regions presenting small "pores".
40
VIEW
ML00136 / Jun.2018
Hydrogen Cracks of Subsea Studs
M - Low Alloy Medium Carbon QTP - FastenerAp - SubseaCd - Hydrogen Embrittlement
Cm - As polished micrographyDf - Crack
As polished micrography of the longitudinal section of the stud at the cracking transverse to the axis. It looks like inclusions/possible banding regions are contributing for the cracking.
38
VIEW
ML00136 / Jun.2018
Hydrogen Cracks of Subsea Studs
M - Low Alloy Medium Carbon QTP - FastenerAp - SubseaCd - Hydrogen Embrittlement
Cm - As polished micrographyDf - Crack
Micrography of the bottom of the thread fillet, presenting secondary cracks of intergranular morphology, not yet opened.
35
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 - Crack
ML00130 — Fatigue Fracture of Overloaded BoltsM - Low Alloy Medium Carbon QTP - FastenerAp - O&G Well DrillingCd - Mechanical Fatigue
Micrographic detail of the cracking adjacent to the fracture. It is a secondary cracking that was created by overloading and was propagating by fatigue.
90
VIEW
ML00130 / Jun.2018
Fatigue Fracture of Overloaded Bolts
M - Low Alloy Medium Carbon QTP - FastenerAp - O&G Well DrillingCd - Mechanical Fatigue
Cm - Nital Etched Micrography by OMDf - Crack
ML00103 — Brittle Fracture of a Free-Cutting ConnectorM - Low Carbon SteelP - Machined PartAp - ShipCd - Brittle Fracture
Micrographic detail of the longitudinal section of the fitting at the thread, showing a crack at the bottom of the thread.
53
VIEW
ML00103 / Nov.2017
Brittle Fracture of a Free-Cutting Connector
M - Low Carbon SteelP - Machined PartAp - ShipCd - Brittle Fracture
Cm - Nital Etched Micrography by OMDf - Crack
ML00099 — Forging Defect in a Cadmium Plated NutM - Medium Carbon SteelP - NutAp - PipingCd - Fabrication Defect
Micrography of the nut in a section transverse to the surface indication. There are several microcracks (parallel and perpendicular to the nut surface) filled with oxides. The nut presented a martensitic microstructure in the center of the thickness and a ferritic-bainitic microstructure at surface and adjacent to the defect, due to decarburization occurred during high temperature forging.
130
VIEW
ML00099 / Jan.2018
Forging Defect in a Cadmium Plated Nut
M - Medium Carbon SteelP - NutAp - PipingCd - Fabrication Defect
Cm - Nital Etched Micrography by OMDf - Crack