Nital Etched Micrography by OM

9 cases · 68 images

Crevice Corrosion in a Subsea System — Aspect Before Analysis

Condition: Hydrogen Embrittlement 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 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 bolt showing a martensitic structure, with segregation bands evidenced by the chemical etch.
99
VIEW
ML00126 / Mar.2018
Hydrogen Fracture of Subsea Allen Bolts
M - Low Alloy Medium Carbon QTP - Coated ProductAp - SubseaCd - Hydrogen Embrittlement
Cm - Nital Etched Micrography by OMDf - Banded Structure
Micrographic detail of a longitudinal section of the pin, at the fracture position, showing secondary cracks with intergranular and transgranular morphology.
59
VIEW
ML00009 / Sep.2017
Hydrogen Cracking of a 5" Drill Pipe S135
M - Low Alloy Medium Carbon QTP - Drill PipeAp - SubseaCd - Hydrogen Embrittlement
Cm - Nital Etched Micrography by OMDf - Brittle Cracks
Micrography of a longitudinal section of the pin, in the center. The low carbon content of the steel in the center of the pin makes the structure bainitic even though it was quenched and tempered after carburizing.
80
VIEW
ML00081 / Aug.2017
Hydrogen Cracking of a Chromium Plated Carburized Pin
M - Low Alloy for Thermochemical TreatmentP - Chromium PlatedAp - AutomotiveCd - Hydrogen Embrittlement
Cm - Nital Etched Micrography by OMDf - In the Center of the Thickness
Micrographic detail of the quenched and tempered martensitic structure of the pin tool joint.
83
VIEW
ML00088 / Dec.2017
Hydrogen Cracking of an API 5D S135 Drill Pipe
M - Low Alloy Medium Carbon QTP - Drill PipeAp - SubseaCd - Hydrogen Embrittlement
Cm - Nital Etched Micrography by OMDf - Martensite
Micrography of the longitudinal section of the link, presenting secondary cracks in the longitudinal direction, following segregation bands in the material.
541
VIEW
ML00079 / Jul.2017
Hydrogen Cracking of a Maritime Chain Link
M - High Strength Low AlloyP - Chain LinkAp - OffshoreCd - Hydrogen Embrittlement
Cm - Nital Etched Micrography by OMDf - Secondary Cracks
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

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

+8 more from this case →

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.
32
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.
26
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 a crack from the thread fillet, of a ductile aspect, opened during torque.
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 - Fracture

+3 more from this case →

ML00126 — Hydrogen Fracture of Subsea Allen BoltsM - Low Alloy Medium Carbon QTP - Coated ProductAp - SubseaCd - Hydrogen Embrittlement
Micrography of the longitudinal section of the bolt at the bottom of the thread fillet, showing the uniform martensitic structure, not strain hardened.
90
VIEW
ML00126 / Mar.2018
Hydrogen Fracture of Subsea Allen Bolts
M - Low Alloy Medium Carbon QTP - Coated ProductAp - SubseaCd - Hydrogen Embrittlement
Cm - Nital Etched Micrography by OMDf - Uniform Structure
Micrography of the longitudinal section of the bolt at the top of the thread fillet, showing a small circunferential cracking typically of a rolling process to manufacture the thread. The thread presented no evidences of plastic deformation suggesting that the heat treatment was applied later. It is important to mention that this cracking presented no influence in the fracture of the bolt.
101
VIEW
ML00126 / Mar.2018
Hydrogen Fracture of Subsea Allen Bolts
M - Low Alloy Medium Carbon QTP - Coated ProductAp - SubseaCd - Hydrogen Embrittlement
Cm - Nital Etched Micrography by OMDf - Rolled Thread
Micrography of the longitudinal section of the bolt in the center of the thickness (ND 5/8") showing a uniform martensitic structure.
67
VIEW
ML00126 / Mar.2018
Hydrogen Fracture of Subsea Allen Bolts
M - Low Alloy Medium Carbon QTP - Coated ProductAp - SubseaCd - Hydrogen Embrittlement
Cm - Nital Etched Micrography by OMDf - Martensite
Micrographic detail of the martensitic structure, uniform in the longitudinal section of the bolt, in the center of the thickness (ND 5/8"). The hardness values of the bolts varied from 39 to 41 HRc.
63
VIEW
ML00126 / Mar.2018
Hydrogen Fracture of Subsea Allen Bolts
M - Low Alloy Medium Carbon QTP - Coated ProductAp - SubseaCd - Hydrogen Embrittlement
Cm - Nital Etched Micrography by OMDf - Martensite
Micrography, after NItal etching, of the longitudinal section of the bolt, at the fracture (top of the figure), starting from the bottom of the thread (to the left side of the figure). The presence of the coating at the bolt surface shows that the fracture occurred without corrosion.
56
VIEW
ML00126 / Mar.2018
Hydrogen Fracture of Subsea Allen Bolts
M - Low Alloy Medium Carbon QTP - Coated ProductAp - SubseaCd - Hydrogen Embrittlement
Cm - Nital Etched Micrography by OMDf - Fracture

+2 more from this case →

ML00009 — Hydrogen Cracking of a 5" Drill Pipe S135M - Low Alloy Medium Carbon QTP - Drill PipeAp - SubseaCd - Hydrogen Embrittlement
Micrography of the longitudinal section of the pin showing a tempered martensite structure, with bands that are associated to segregations. The pin presented average hardness of 38 HRc in the section.
63
VIEW
ML00009 / Sep.2017
Hydrogen Cracking of a 5" Drill Pipe S135
M - Low Alloy Medium Carbon QTP - Drill PipeAp - SubseaCd - Hydrogen Embrittlement
Cm - Nital Etched Micrography by OMDf - Banded Structure
Micrography of the longitudinal section of the pin showing a tempered martensite structure. The pin presented average hardness of 38 HRc in the section.
53
VIEW
ML00009 / Sep.2017
Hydrogen Cracking of a 5" Drill Pipe S135
M - Low Alloy Medium Carbon QTP - Drill PipeAp - SubseaCd - Hydrogen Embrittlement
Cm - Nital Etched Micrography by OMDf - Martensite
Micrographic detail of the longitudinal section of the pin showing a tempered martensite structure. The pin presented average hardness of 38 HRc in the section.
54
VIEW
ML00009 / Sep.2017
Hydrogen Cracking of a 5" Drill Pipe S135
M - Low Alloy Medium Carbon QTP - Drill PipeAp - SubseaCd - Hydrogen Embrittlement
Cm - Nital Etched Micrography by OMDf - Martensite
Micrography of a longitudinal section of the pin, at the fracture position, showing a low magnification aspect of the fracture surface (top of the figure) and secondary cracks associated to the segregation band.
50
VIEW
ML00009 / Sep.2017
Hydrogen Cracking of a 5" Drill Pipe S135
M - Low Alloy Medium Carbon QTP - Drill PipeAp - SubseaCd - Hydrogen Embrittlement
Cm - Nital Etched Micrography by OMDf - Cracking
Micrography of a longitudinal section of the pin, at the fracture position, showing the main fracture surface and secondary cracks associated to a segregation band, with an intergranular morphology.
49
VIEW
ML00009 / Sep.2017
Hydrogen Cracking of a 5" Drill Pipe S135
M - Low Alloy Medium Carbon QTP - Drill PipeAp - SubseaCd - Hydrogen Embrittlement
Cm - Nital Etched Micrography by OMDf - Intergranular Cracking

+1 more from this case →

ML00081 — Hydrogen Cracking of a Chromium Plated Carburized PinM - Low Alloy for Thermochemical TreatmentP - Chromium PlatedAp - AutomotiveCd - Hydrogen Embrittlement
Micrographic detail of the bainitic structure in the center of the pin, that was quenched and tempered after carburizing.
75
VIEW
ML00081 / Aug.2017
Hydrogen Cracking of a Chromium Plated Carburized Pin
M - Low Alloy for Thermochemical TreatmentP - Chromium PlatedAp - AutomotiveCd - Hydrogen Embrittlement
Cm - Nital Etched Micrography by OMDf - Bainite
Micrography of a longitudinal section of the pin, at the surface. The pin was carburized, quenched and tempered (yellow diffuse layer at the surface, 0.5 mm of extension) and a white layer of hard chromium plating is evident.
108
VIEW
ML00081 / Aug.2017
Hydrogen Cracking of a Chromium Plated Carburized Pin
M - Low Alloy for Thermochemical TreatmentP - Chromium PlatedAp - AutomotiveCd - Hydrogen Embrittlement
Cm - Nital Etched Micrography by OMDf - Carburized Layer
Micrographic detail a longitudinal section of the pin, at the surface, showing the case hardened. The pin carburized, quenched and tempered structure presents a gradient of carbon content and consequently a gradient of martensitic structure and hardness. Close to the surface the hardness level is 742 HV1 .
86
VIEW
ML00081 / Aug.2017
Hydrogen Cracking of a Chromium Plated Carburized Pin
M - Low Alloy for Thermochemical TreatmentP - Chromium PlatedAp - AutomotiveCd - Hydrogen Embrittlement
Cm - Nital Etched Micrography by OMDf - At the Surface
Micrographic detail of the high hardness martensitic structure at the surface of the pin, that was quenched and tempered after carburizing.
66
VIEW
ML00081 / Aug.2017
Hydrogen Cracking of a Chromium Plated Carburized Pin
M - Low Alloy for Thermochemical TreatmentP - Chromium PlatedAp - AutomotiveCd - Hydrogen Embrittlement
Cm - Nital Etched Micrography by OMDf - Martensite
Micrography that presents a secondary cracking (adjacent to the broken surface) propagating 500 microns from the surface, where there is a white layer of hard chromium .
78
VIEW
ML00081 / Aug.2017
Hydrogen Cracking of a Chromium Plated Carburized Pin
M - Low Alloy for Thermochemical TreatmentP - Chromium PlatedAp - AutomotiveCd - Hydrogen Embrittlement
Cm - Nital Etched Micrography by OMDf - Carburized Layer

+1 more from this case →

ML00088 — Hydrogen Cracking of an API 5D S135 Drill PipeM - Low Alloy Medium Carbon QTP - Drill PipeAp - SubseaCd - Hydrogen Embrittlement
Micrography of the pin longitudinal section (transverse to the fracture), in low magnification, close to the external surface of the pin (right side of the figure). The fracture (in the top of the figure) is flat, also evidencing no plastic deformation.
41
VIEW
ML00088 / Dec.2017
Hydrogen Cracking of an API 5D S135 Drill Pipe
M - Low Alloy Medium Carbon QTP - Drill PipeAp - SubseaCd - Hydrogen Embrittlement
Cm - Nital Etched Micrography by OMDf - Fracture
Micrographic detail of a secondary intergranular cracking at the pin longitudinal section (transverse to the fracture).
38
VIEW
ML00088 / Dec.2017
Hydrogen Cracking of an API 5D S135 Drill Pipe
M - Low Alloy Medium Carbon QTP - Drill PipeAp - SubseaCd - Hydrogen Embrittlement
Cm - Nital Etched Micrography by OMDf - Intergranular Cracking
ML00079 — Hydrogen Cracking of a Maritime Chain LinkM - High Strength Low AlloyP - Chain LinkAp - OffshoreCd - Hydrogen Embrittlement
Micrographic detail of the longitudinal section of the link, presenting internal cracks of intergranular morphology, typical of a hydrogen assisted mechanism.
52
VIEW
ML00079 / Jul.2017
Hydrogen Cracking of a Maritime Chain Link
M - High Strength Low AlloyP - Chain LinkAp - OffshoreCd - Hydrogen Embrittlement
Cm - Nital Etched Micrography by OMDf - Intergranular Cracking
Micrography of a longitudinal section of the link, presenting a tempered martensitic structure, typical of a quenching and tempering heat treatment and compatible with the link hardness of 43 HRc.
67
VIEW
ML00079 / Jul.2017
Hydrogen Cracking of a Maritime Chain Link
M - High Strength Low AlloyP - Chain LinkAp - OffshoreCd - Hydrogen Embrittlement
Cm - Nital Etched Micrography by OMDf - Martensite
Micrography of the longitudinal section of the link, close to the fracture surface (in the top of the figure). There are secondary cracks parallel to the fracture.
33
VIEW
ML00079 / Jul.2017
Hydrogen Cracking of a Maritime Chain Link
M - High Strength Low AlloyP - Chain LinkAp - OffshoreCd - Hydrogen Embrittlement
Cm - Nital Etched Micrography by OMDf - Secondary Cracks
Micrographic detail of the longitudinal section of the link, close to the fracture surface, presenting the intergranular morphology of the secondary cracks, parallel to the fracture.
29
VIEW
ML00079 / Jul.2017
Hydrogen Cracking of a Maritime Chain Link
M - High Strength Low AlloyP - Chain LinkAp - OffshoreCd - Hydrogen Embrittlement
Cm - Nital Etched Micrography by OMDf - Intergranular Cracking
Micrographic detail of the intergranular secondary cracks, parallel to the fracture, typical of a hydrogen assisted cracking.
29
VIEW
ML00079 / Jul.2017
Hydrogen Cracking of a Maritime Chain Link
M - High Strength Low AlloyP - Chain LinkAp - OffshoreCd - Hydrogen Embrittlement
Cm - Nital Etched Micrography by OMDf - Intergranular Cracking
ML00077 — Hydrogen Cracking of LAS Subsea BoltsM - Low Alloy Medium Carbon QTP - FastenerAp - SubseaCd - Hydrogen Embrittlement
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
Micrography of a longitudinal section of the bolt, showing the (secondary) cracks, longitudinal, connected to the fracture surface (in the top).
78
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 - Fracture
Micrographic detail of the (secondary) cracks, longitudinal, connected to the fracture surface (in the top).
69
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 - Fracture
Micrographic detail of the (secondary) cracks, longitudinal, connected to the fracture surface (in the top).
72
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 - Fracture

+2 more from this case →