Oil and Gas

8 cases · 56 images

Crevice Corrosion in a Subsea System — Aspect Before Analysis

Condition: Hydrogen Capture method: Optical Microscope clear all

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In a cut perpendicular to the macroscopic secondary crack it is possible to see several brittle microcracks (branched), indicating that an embrittlement has occurred.
22
VIEW
ML00176 / Nov.2021
Hydride Formation in a Titanium Blade
M - Unalloyed TitaniumP - BladeAp - Oil and GasCd - Hydride Formation
Cm - As polished micrographyDf - Brittle Cracks
Micrography of the longitudinal section of the stud presenting a tempered martensite structure, slightly banded. Hardness 45 HRc.
33
VIEW
ML00127 / May.2018
Hydrogen Cracks of Cadmium Plated Studs
M - Low Alloy Medium Carbon QTP - Allen StudAp - Oil and GasCd - Hydrogen Embrittlement
Cm - Nital Etched Micrography by OMDf - Martensite
Micrography of the longitudinal section of the forging material, presenting a granular austenite, precipitation hardened.
84
VIEW
ML00078 / Jun.2017
Hydrogen Cracking of IN 718 Subsea Connector
M - NiCrFe AlloyP - ForgingAp - SubseaCd - Hydrogen Embrittlement
Cm - Kalling Etched Micrography by OMDf - Longitudinal Section
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
The longitudinal section of the spring wire shows a strain hardened martensitic structure, aged to high strength (602 HV 0.3kg). Previous austenite grains are elongated.
55
VIEW
ML00076 / Jun.2017
Hydrogen Cracking of a 17-7 PH Subsea Spring
M - Precipitation Hardened Stainless SteelP - WireAp - SubseaCd - Hydrogen Embrittlement
Cm - Kalling Etched Micrography by OMDf - Longitudinal Section
The stud presents an austenitic structure, with primary and secondary precipitates of a size that is visible in low magnification microscopy.
55
VIEW
ML00075 / Jun.2018
Hydrogen Cracking of IN 718 Subsea Fasteners
M - NiCrFe AlloyP - StudAp - SubseaCd - Hydrogen Embrittlement
Cm - Kalling Etched Micrography by OMDf - Austenite
Micrographic aspect of the aged martensite structure of the 17-4 PH bolt, about 37 HRc.
94
VIEW
ML00074 / Jun.2018
Hydrogen Cracking of a 17-4 PH Subsea Bolt
M - Precipitation Hardened Stainless SteelP - FastenerAp - SubseaCd - Hydrogen Embrittlement
Cm - Kalling Etched Micrography by OMDf - Martensite
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.
472
VIEW
ML00073 / Jun.2018
Hydrogen Cracking of a LAS Subsea Fastener
M - Low Alloy Medium Carbon QTP - FastenerAp - SubseaCd - Hydrogen Embrittlement
Cm - Micrography by OMDf - Intergranular Cracking

More from these cases

ML00176 — Hydride Formation in a Titanium BladeM - Unalloyed TitaniumP - BladeAp - Oil and GasCd - Hydride Formation
The main crack is to the top and the blade surface is to the right, in this micrography that does not reveal any plastic deformation, with transgranular and integranular cracks.
24
VIEW
ML00176 / Nov.2021
Hydride Formation in a Titanium Blade
M - Unalloyed TitaniumP - BladeAp - Oil and GasCd - Hydride Formation
Cm - Micrography by OM, HF + HNO3 + H2O etchDf - Brittle Fracture
Transgranular and integranular cracks in the alpha matrix full of acicular hydrides .
17
VIEW
ML00176 / Nov.2021
Hydride Formation in a Titanium Blade
M - Unalloyed TitaniumP - BladeAp - Oil and GasCd - Hydride Formation
Cm - Micrography by OM, HF + HNO3 + H2O etchDf - Hydride Formation
ML00127 — Hydrogen Cracks of Cadmium Plated StudsM - Low Alloy Medium Carbon QTP - Allen StudAp - Oil and GasCd - Hydrogen Embrittlement
Micrography of the longitudinal section of the stud presenting a tempered martensite structure in the center of the thickness.
33
VIEW
ML00127 / May.2018
Hydrogen Cracks of Cadmium Plated Studs
M - Low Alloy Medium Carbon QTP - Allen StudAp - Oil and GasCd - Hydrogen Embrittlement
Cm - Nital Etched Micrography by OMDf - Martensite
Low magnification micrographic image of the stud thread, in the longitudinal section, showing the segregation lines of the steel cut at the thread indicating it was machined.
30
VIEW
ML00127 / May.2018
Hydrogen Cracks of Cadmium Plated Studs
M - Low Alloy Medium Carbon QTP - Allen StudAp - Oil and GasCd - Hydrogen Embrittlement
Cm - Nital Etched Micrography by OMDf - Machined Thread
Micrographic detail of the stud at the thread bottom.
27
VIEW
ML00127 / May.2018
Hydrogen Cracks of Cadmium Plated Studs
M - Low Alloy Medium Carbon QTP - Allen StudAp - Oil and GasCd - Hydrogen Embrittlement
Cm - Nital Etched Micrography by OMDf - Machined Thread
Micrographic detail of the thread top, showing that the thread was machined.
29
VIEW
ML00127 / May.2018
Hydrogen Cracks of Cadmium Plated Studs
M - Low Alloy Medium Carbon QTP - Allen StudAp - Oil and GasCd - Hydrogen Embrittlement
Cm - Nital Etched Micrography by OMDf - Machined Thread
Micrography of the longitudinal section of the stud showing internal cracks, secondary (not the cracks that opened the fracture). It is evident that the cracking from the thread fillet, of a ductile aspect, presented a different aspect than the internal cracks, of a brittle aspect.
31
VIEW
ML00127 / May.2018
Hydrogen Cracks of Cadmium Plated Studs
M - Low Alloy Medium Carbon QTP - Allen StudAp - Oil and GasCd - Hydrogen Embrittlement
Cm - As polished micrographyDf - Cracks

+4 more from this case →

ML00078 — Hydrogen Cracking of IN 718 Subsea ConnectorM - NiCrFe AlloyP - ForgingAp - SubseaCd - Hydrogen Embrittlement
Micrography of the longitudinal section of the conector, at the fracture position, showing secondary cracks from the fracture surface.
64
VIEW
ML00078 / Jun.2017
Hydrogen Cracking of IN 718 Subsea Connector
M - NiCrFe AlloyP - ForgingAp - SubseaCd - Hydrogen Embrittlement
Cm - Kalling Etched Micrography by OMDf - Fracture
The micrographic detail of the longitudinal section at the fracture surface shows intergranular morphology for the secondary cracks (longitudinal to the forging axis).
64
VIEW
ML00078 / Jun.2017
Hydrogen Cracking of IN 718 Subsea Connector
M - NiCrFe AlloyP - ForgingAp - SubseaCd - Hydrogen Embrittlement
Cm - Kalling Etched Micrography by OMDf - Secondary Cracks
Micrographic detail of a longitudinal section of the connector, at the fracture surface (in the top), showing intergranular secondary cracks.
54
VIEW
ML00078 / Jun.2017
Hydrogen Cracking of IN 718 Subsea Connector
M - NiCrFe AlloyP - ForgingAp - SubseaCd - Hydrogen Embrittlement
Cm - Kalling Etched Micrography by OMDf - Intergranular Cracking
Micrographic detail of a longitudinal section of the connector, at the fracture surface (in the top), showing intergranular secondary cracks. There is a large amount of delta phase precipitated intergranular and intragranluar.
48
VIEW
ML00078 / Jun.2017
Hydrogen Cracking of IN 718 Subsea Connector
M - NiCrFe AlloyP - ForgingAp - SubseaCd - Hydrogen Embrittlement
Cm - Kalling Etched Micrography by OMDf - Secondary Cracks
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 →

ML00076 — Hydrogen Cracking of a 17-7 PH Subsea SpringM - Precipitation Hardened Stainless SteelP - WireAp - SubseaCd - Hydrogen Embrittlement
Micrographic detail of the strain hardened aged martensitic structure. Small aligned delta ferrite islands can be seen.
51
VIEW
ML00076 / Jun.2017
Hydrogen Cracking of a 17-7 PH Subsea Spring
M - Precipitation Hardened Stainless SteelP - WireAp - SubseaCd - Hydrogen Embrittlement
Cm - Kalling Etched Micrography by OMDf - Longitudinal Section
The transverse section of the spring wire shows a strain hardened martensitic structure, aged to high strength (602 HV 0.3kg).
48
VIEW
ML00076 / Jun.2017
Hydrogen Cracking of a 17-7 PH Subsea Spring
M - Precipitation Hardened Stainless SteelP - WireAp - SubseaCd - Hydrogen Embrittlement
Cm - Kalling Etched Micrography by OMDf - Transverse Section
Micrographic detail of the strain hardened aged martensitic structure.
48
VIEW
ML00076 / Jun.2017
Hydrogen Cracking of a 17-7 PH Subsea Spring
M - Precipitation Hardened Stainless SteelP - WireAp - SubseaCd - Hydrogen Embrittlement
Cm - Kalling Etched Micrography by OMDf - Transverse Section
Micrography of a longitudinal section of the wire, at the fracture surface (top of the figure) evidencing the intergranular and transgranular aspects of the hydrogen assisted cracking mechanism.
37
VIEW
ML00076 / Jun.2017
Hydrogen Cracking of a 17-7 PH Subsea Spring
M - Precipitation Hardened Stainless SteelP - WireAp - SubseaCd - Hydrogen Embrittlement
Cm - Micrography by OM using A262 Method ADf - Secondary Cracks
Micrographic detail of a longitudinal section of the wire, at the fracture surface (top of the figure) evidencing the intergranular and transgranular aspects of the hydrogen assisted cracking mechanism. The electrolytic oxalic acid etch reveals the delta ferrite phase. Compare with the Kalling etch in the other figure.
31
VIEW
ML00076 / Jun.2017
Hydrogen Cracking of a 17-7 PH Subsea Spring
M - Precipitation Hardened Stainless SteelP - WireAp - SubseaCd - Hydrogen Embrittlement
Cm - Micrography by OM using A262 Method ADf - Fracture

+2 more from this case →

ML00075 — Hydrogen Cracking of IN 718 Subsea FastenersM - NiCrFe AlloyP - StudAp - SubseaCd - Hydrogen Embrittlement
The stud structure evidences grain boundaries precipitation of probably delta phase (an overaging of the hardening precipitate).
49
VIEW
ML00075 / Jun.2018
Hydrogen Cracking of IN 718 Subsea Fasteners
M - NiCrFe AlloyP - StudAp - SubseaCd - Hydrogen Embrittlement
Cm - Kalling Etched Micrography by OMDf - Austenite
Micrography of a longitudinal section of the stud, at the fracture surface, in the thread.
44
VIEW
ML00075 / Jun.2018
Hydrogen Cracking of IN 718 Subsea Fasteners
M - NiCrFe AlloyP - StudAp - SubseaCd - Hydrogen Embrittlement
Cm - Kalling Etched Micrography by OMDf - Fracture
Micrographic detail of a longitudinal section of the stud, at the fracture surface, in the thread. It is possible to see primary precipitates (yellow) already cracked and intergranular propagation.
37
VIEW
ML00075 / Jun.2018
Hydrogen Cracking of IN 718 Subsea Fasteners
M - NiCrFe AlloyP - StudAp - SubseaCd - Hydrogen Embrittlement
Cm - Kalling Etched Micrography by OMDf - Intergranular Cracking
Micrography of a longitudinal section of the stud, at the fracture surface in the center of the thickness, showing a long secondary cracking (vertical in the left).
35
VIEW
ML00075 / Jun.2018
Hydrogen Cracking of IN 718 Subsea Fasteners
M - NiCrFe AlloyP - StudAp - SubseaCd - Hydrogen Embrittlement
Cm - Kalling Etched Micrography by OMDf - Secondary Cracks
Micrographic detail of the longitudinal section of the stud, at the secondary cracking.
27
VIEW
ML00075 / Jun.2018
Hydrogen Cracking of IN 718 Subsea Fasteners
M - NiCrFe AlloyP - StudAp - SubseaCd - Hydrogen Embrittlement
Cm - Kalling Etched Micrography by OMDf - Brittle Cracks
ML00074 — Hydrogen Cracking of a 17-4 PH Subsea BoltM - Precipitation Hardened Stainless SteelP - FastenerAp - SubseaCd - Hydrogen Embrittlement
Micrographic detail of the aged martensite structure of the 17-4 PH bolt, about 37 HRc.
73
VIEW
ML00074 / Jun.2018
Hydrogen Cracking of a 17-4 PH Subsea Bolt
M - Precipitation Hardened Stainless SteelP - FastenerAp - SubseaCd - Hydrogen Embrittlement
Cm - Kalling Etched Micrography by OMDf - Martensite
Micrography of the longitudinal section of the bolt, at the bottom of the thread fillet, showing that the fracture is intergranular in this position.
71
VIEW
ML00074 / Jun.2018
Hydrogen Cracking of a 17-4 PH Subsea Bolt
M - Precipitation Hardened Stainless SteelP - FastenerAp - SubseaCd - Hydrogen Embrittlement
Cm - Kalling Etched Micrography by OMDf - Longitudinal Section
Micrographic detail of intergranular cracks close to the fracture of the bolt, near the bolt surface where the macroscopi aspect was brittle.
82
VIEW
ML00074 / Jun.2018
Hydrogen Cracking of a 17-4 PH Subsea Bolt
M - Precipitation Hardened Stainless SteelP - FastenerAp - SubseaCd - Hydrogen Embrittlement
Cm - Kalling Etched Micrography by OMDf - Intergranular Cracking
The micrography, in the "as polished" condition, of the longitudinal section of the bolt showing that there are non-continuous longitudinal cracks, intergranular, associated to regions of impurities, probably segregation bands, as evidenced by the grey elongated sulfide inclusions.
76
VIEW
ML00074 / Jun.2018
Hydrogen Cracking of a 17-4 PH Subsea Bolt
M - Precipitation Hardened Stainless SteelP - FastenerAp - SubseaCd - Hydrogen Embrittlement
Cm - Micrography by OMDf - Intergranular Cracking
Micrographic detail of the longitudinal cracks in the middle of the bolt, that generaate the secondary cracks that appear at the fracture surface.
79
VIEW
ML00074 / Jun.2018
Hydrogen Cracking of a 17-4 PH Subsea Bolt
M - Precipitation Hardened Stainless SteelP - FastenerAp - SubseaCd - Hydrogen Embrittlement
Cm - Kalling Etched Micrography by OMDf - Intergranular Cracking
ML00073 — Hydrogen Cracking of a LAS Subsea FastenerM - Low Alloy Medium Carbon QTP - FastenerAp - SubseaCd - Hydrogen Embrittlement
Tempered martensitic structure of a longitudinal section of the fastener. Slightly banded material. Hardness level about 42 HRc.
59
VIEW
ML00073 / Jun.2018
Hydrogen Cracking of a LAS Subsea Fastener
M - Low Alloy Medium Carbon QTP - FastenerAp - SubseaCd - Hydrogen Embrittlement
Cm - Nital Etched Micrography by OMDf - Martensite
Micrography of a longitudinal section of the fastener, at the threat fillet, showing a transverse cracking.
68
VIEW
ML00073 / Jun.2018
Hydrogen Cracking of a LAS Subsea Fastener
M - Low Alloy Medium Carbon QTP - FastenerAp - SubseaCd - Hydrogen Embrittlement
Cm - Nital Etched Micrography by OMDf - Cracking
Micrography of the secondary crack, in the fillet adjacent to the nut position, where it was opened to the surface.
65
VIEW
ML00073 / Jun.2018
Hydrogen Cracking of a LAS Subsea Fastener
M - Low Alloy Medium Carbon QTP - FastenerAp - SubseaCd - Hydrogen Embrittlement
Cm - Nital Etched Micrography by OMDf - Cracking
Micrographic detail of the secondary crack, in the fillet adjacent to the nut position, where it was opened to the surface.
46
VIEW
ML00073 / Jun.2018
Hydrogen Cracking of a LAS Subsea Fastener
M - Low Alloy Medium Carbon QTP - FastenerAp - SubseaCd - Hydrogen Embrittlement
Cm - Nital Etched Micrography by OMDf - Cracking
Thin intergranular cracks in the center of the bolt thickness. Not continuous and not opened to the surface.
46
VIEW
ML00073 / Jun.2018
Hydrogen Cracking of a LAS Subsea Fastener
M - Low Alloy Medium Carbon QTP - FastenerAp - SubseaCd - Hydrogen Embrittlement
Cm - Nital Etched Micrography by OMDf - Intergranular Cracking

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