Optical Microscope

100 cases · 889 images

Crevice Corrosion in a Subsea System — Aspect Before Analysis

Standard: UNS clear all

Optical Microscope — sub-branches

As polished micrography 67Chromic Acid Electrolytic Etched 1Eletrolytically Etched Micrography by OM 11FeCl3+HCl+Ethanol Etched Micro 15FeCl3+HCl+H2O Etched Micro 28Glyceregia Etched Micrography by OM 1H2SO4+HNO3+H3PO4 Etched Micro 1Kalling Etched Micrography by OM 190Keller Etched Micrography by OM 31Kroll Etched Micrography by OM 5Micro by OM, HCl + Ethanol + Picric Acid 12Micrography by OM 41Micrography by OM using A262 Method A 68Micrography by OM, HF + HNO3 + H2O etch 8NH4OH+H2O+H2O2 Etched Micro 8NaOH Electrolytic Etched Micro 82Nital Etched Micrography by OM 300Oxalic Acid Electrolytic Etch 20

Results

SortNewestOldestTitle A-ZTitle Z-A
Microstructure of the spring in a transverse section, presenting an aged martensitic structure.
96
VIEW
ML00137 / Mar.2021
Brittle Fracture of a 15-5 PH Valve Spring
M - Precipitation Hardened Stainless SteelP - SpringAp - Oil and GasCd - Brittle Behavior
Cm - Kalling Etched Micrography by OMDf - Martensite
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
Microstructural analysis of the valve body structure, close to the position where the cracking has occurred. The structure is ferritic austenitic, with a large amount of detrimental phases associated to the ferritic structure, probably sigma phase.
106
VIEW
ML00134 / Aug.2020
Brittle Fracture of a Superduplex Valve Body
M - Super Duplex Stainless SteelP - Fabrication WeldAp - SubseaCd - Brittle Fracture
Cm - NaOH Electrolytic Etched MicroDf - Sigma
Micrographic detail of the weld metal with islands of a coarse ferritic structure, degradated (recristalized) from an acicular morphology during to the long heat treatment cycle in high temperature. The post welding heat treatment (PWHT) was conducted during 12 hours at 640°C.
700
VIEW
ML00129 / Apr.2018
Non qualified WPS for High Strength Steel
M - Low Alloy Medium Carbon QTP - Welded Testpiece for QualificationAp - Oil and GasCd - Non qualified
Cm - Nital Etched Micrography by OMDf - Coarse Structure
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
Micrography of a transverse section of the platesheet presenting a duplex structure, alpha (light yellow) and beta (orange) phases.
214
VIEW
ML00125 / Mar.2018
Dezincification of a Cooler Tubesheet
M - BrassP - PlateAp - ShipCd - Preferential Dissolution
Cm - FeCl3+HCl+Ethanol Etched MicroDf - Alpha and Beta
Micrography of a transverse section of the ring presenting a uniform tempered martensite structure.
43
VIEW
ML00124 / Feb.2018
MIC of a Martensitic Valve Ring
M - Martensitic Stainless SteelP - ForgingAp - EnergyCd - Brittle Behavior
Cm - Kalling Etched Micrography by OMDf - Martensite

More from these cases

ML00137 — Brittle Fracture of a 15-5 PH Valve SpringM - Precipitation Hardened Stainless SteelP - SpringAp - Oil and GasCd - Brittle Behavior
Micrography of a longitudinal section of the spring indicating that under the deposits there are intergranular cracks initiating at the spring surface.
72
VIEW
ML00137 / Mar.2021
Brittle Fracture of a 15-5 PH Valve Spring
M - Precipitation Hardened Stainless SteelP - SpringAp - Oil and GasCd - Brittle Behavior
Cm - As polished micrographyDf - Intergranular Cracking
Micrographic detail of a longitudinal section of the spring indicating that under the deposits there are intergranular cracks initiating at the spring surface.
65
VIEW
ML00137 / Mar.2021
Brittle Fracture of a 15-5 PH Valve Spring
M - Precipitation Hardened Stainless SteelP - SpringAp - Oil and GasCd - Brittle Behavior
Cm - As polished micrographyDf - Intergranular Cracking
Micrographic detail of a longitudinal section of the spring indicating that under the deposits there are intergranular cracks initiating at the spring surface.
60
VIEW
ML00137 / Mar.2021
Brittle Fracture of a 15-5 PH Valve Spring
M - Precipitation Hardened Stainless SteelP - SpringAp - Oil and GasCd - Brittle Behavior
Cm - Kalling Etched Micrography by OMDf - Intergranular Cracking
Micrography of a longitudinal section of the spring indicating that under the deposits there are intergranular cracks initiating at the spring surface.
57
VIEW
ML00137 / Mar.2021
Brittle Fracture of a 15-5 PH Valve Spring
M - Precipitation Hardened Stainless SteelP - SpringAp - Oil and GasCd - Brittle Behavior
Cm - Kalling Etched Micrography by OMDf - Intergranular Cracking
Micrographic detail of a longitudinal section of the spring indicating that under the deposits there are intergranular cracks initiating at the spring surface.
57
VIEW
ML00137 / Mar.2021
Brittle Fracture of a 15-5 PH Valve Spring
M - Precipitation Hardened Stainless SteelP - SpringAp - Oil and GasCd - Brittle Behavior
Cm - Kalling Etched Micrography by OMDf - Intergranular Cracking

+7 more from this case →

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 →

ML00134 — Brittle Fracture of a Superduplex Valve BodyM - Super Duplex Stainless SteelP - Fabrication WeldAp - SubseaCd - Brittle Fracture
Micrographic detail of the valve body structure, close to the position where the cracking has occurred. The structure is ferritic austenitic, with a large amount of detrimental phases associated to the ferritic structure, probably sigma phase.
102
VIEW
ML00134 / Aug.2020
Brittle Fracture of a Superduplex Valve Body
M - Super Duplex Stainless SteelP - Fabrication WeldAp - SubseaCd - Brittle Fracture
Cm - NaOH Electrolytic Etched MicroDf - Sigma
Metallographic detail of the large amount of sigma phase, associated to the ferritic structure.
105
VIEW
ML00134 / Aug.2020
Brittle Fracture of a Superduplex Valve Body
M - Super Duplex Stainless SteelP - Fabrication WeldAp - SubseaCd - Brittle Fracture
Cm - NaOH Electrolytic Etched MicroDf - Sigma
Microstructural analysis of the valve body structure, far from the position where the cracking has occurred, in the bottom of the body. The structure is ferritic austenitic, with some sigma phase, not in a large amount, indicating the valve structure was not uniform.
67
VIEW
ML00134 / Aug.2020
Brittle Fracture of a Superduplex Valve Body
M - Super Duplex Stainless SteelP - Fabrication WeldAp - SubseaCd - Brittle Fracture
Cm - NaOH Electrolytic Etched MicroDf - Ferrite and Austenite
Micrographic detail of the valve body structure, far from the position where the cracking has occurred, in the bottom of the body. The structure is ferritic austenitic, with some sigma phase, not in a large amount, indicating the valve structure was not uniform.
63
VIEW
ML00134 / Aug.2020
Brittle Fracture of a Superduplex Valve Body
M - Super Duplex Stainless SteelP - Fabrication WeldAp - SubseaCd - Brittle Fracture
Cm - NaOH Electrolytic Etched MicroDf - Ferrite and Austenite
Micrographic detail of the valve body structure, far from the position where the cracking has occurred, in the bottom of the body. The structure is ferritic austenitic, with some sigma phase, not in a large amount, indicating the valve structure was not uniform.
61
VIEW
ML00134 / Aug.2020
Brittle Fracture of a Superduplex Valve Body
M - Super Duplex Stainless SteelP - Fabrication WeldAp - SubseaCd - Brittle Fracture
Cm - NaOH Electrolytic Etched MicroDf - Ferrite and Austenite

+8 more from this case →

ML00129 — Non qualified WPS for High Strength SteelM - Low Alloy Medium Carbon QTP - Welded Testpiece for QualificationAp - Oil and GasCd - Non qualified
Micrography of the weld metal, at the face, presenting regions of large ferritic grains. The acicular ferrite structure in the columnar (previous austenitic) grains has suffered degradation due to the long heat treatment cycle (12 hours) in high temperature.
97
VIEW
ML00129 / Apr.2018
Non qualified WPS for High Strength Steel
M - Low Alloy Medium Carbon QTP - Welded Testpiece for QualificationAp - Oil and GasCd - Non qualified
Cm - Nital Etched Micrography by OMDf - Weld Metal
Micrography of the weld metal, at the face, presenting regions of large ferritic grains. The acicular ferrite has suffered degradation due to the long heat treatment cycle (12 hours) in a temperature of 640°C, that is higher than the recommended for the D2 filler metal.
78
VIEW
ML00129 / Apr.2018
Non qualified WPS for High Strength Steel
M - Low Alloy Medium Carbon QTP - Welded Testpiece for QualificationAp - Oil and GasCd - Non qualified
Cm - Nital Etched Micrography by OMDf - Weld Metal
Micrography of the base metal, in low magnification, showing regions of segregations in a quenched and tempered martensitic structure.
52
VIEW
ML00129 / Apr.2018
Non qualified WPS for High Strength Steel
M - Low Alloy Medium Carbon QTP - Welded Testpiece for QualificationAp - Oil and GasCd - Non qualified
Cm - Nital Etched Micrography by OMDf - Base Metal
Micrography of the base metal showing a quenched and tempered martensitic structure. The base metal adopted in the test coupon presented a hardness level of 217HB (Brinell hardness of the certificate) and after the PWHT cycle the measured base metal hardness is 224 HV10.
59
VIEW
ML00129 / Apr.2018
Non qualified WPS for High Strength Steel
M - Low Alloy Medium Carbon QTP - Welded Testpiece for QualificationAp - Oil and GasCd - Non qualified
Cm - Nital Etched Micrography by OMDf - Base Metal
Micrographic detail of the base metal structure, quenched and tempered martensite. The base metal adopted in the test coupon presented a hardness level of 217HB (Brinell hardness of the certificate) and after the PWHT cycle the measured base metal hardness is 224 HV10.
51
VIEW
ML00129 / Apr.2018
Non qualified WPS for High Strength Steel
M - Low Alloy Medium Carbon QTP - Welded Testpiece for QualificationAp - Oil and GasCd - Non qualified
Cm - Nital Etched Micrography by OMDf - Martensite

+12 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.
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 →

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 at the bottom of the thread fillet, in the "as polished" condition, showing the zinc flakes coating layer, applied by a painting process that do not create metallurgical bonding with the substrate.
82
VIEW
ML00126 / Mar.2018
Hydrogen Fracture of Subsea Allen Bolts
M - Low Alloy Medium Carbon QTP - Coated ProductAp - SubseaCd - Hydrogen Embrittlement
Cm - As polished micrographyDf - Coating Layer
Micrographic detail of the zinc flakes coating layer in the "as polished" condition of a longitudinal section of the bolt.
71
VIEW
ML00126 / Mar.2018
Hydrogen Fracture of Subsea Allen Bolts
M - Low Alloy Medium Carbon QTP - Coated ProductAp - SubseaCd - Hydrogen Embrittlement
Cm - As polished micrographyDf - Coating Layer
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

+5 more from this case →

ML00125 — Dezincification of a Cooler TubesheetM - BrassP - PlateAp - ShipCd - Preferential Dissolution
Micrography of the transverse section of the platesheet at the interface between the corroded and the non-corroded regions. The micrography is in the as polished condition.
140
VIEW
ML00125 / Mar.2018
Dezincification of a Cooler Tubesheet
M - BrassP - PlateAp - ShipCd - Preferential Dissolution
Cm - As polished micrographyDf - Preferential Dissolution
Micrography of the transverse section of the platesheet showing that part of the material (right side in the top of the figure) was lost (corroded).
129
VIEW
ML00125 / Mar.2018
Dezincification of a Cooler Tubesheet
M - BrassP - PlateAp - ShipCd - Preferential Dissolution
Cm - As polished micrographyDf - Preferential Dissolution
Micrographic detail of the dezincification effect, where the beta phase is preferentially corroded, leaving a cooper rich phase (red) that is porous and easily cracks.
121
VIEW
ML00125 / Mar.2018
Dezincification of a Cooler Tubesheet
M - BrassP - PlateAp - ShipCd - Preferential Dissolution
Cm - As polished micrographyDf - Dezincification
Micrographic detail of the dezincification effect, where the beta phase is preferentially corroded, leaving a cooper rich phase (red) that is porous and easily cracks.
130
VIEW
ML00125 / Mar.2018
Dezincification of a Cooler Tubesheet
M - BrassP - PlateAp - ShipCd - Preferential Dissolution
Cm - As polished micrographyDf - Cracks
Micrography showing detachment of material at the surface of the platesheet. The cracks are associated to the dezincification effect, where the beta phase was preferentially corroded and became a weak porous layer.
113
VIEW
ML00125 / Mar.2018
Dezincification of a Cooler Tubesheet
M - BrassP - PlateAp - ShipCd - Preferential Dissolution
Cm - As polished micrographyDf - Crack

+7 more from this case →

ML00124 — MIC of a Martensitic Valve RingM - Martensitic Stainless SteelP - ForgingAp - EnergyCd - Brittle Behavior
Micrography of a transverse section of the ring, at the pitting position, as polished, showing that there are intergranular cracks and the martensitic structure is corroded (chemical dissolution) inside the pitting.
33
VIEW
ML00124 / Feb.2018
MIC of a Martensitic Valve Ring
M - Martensitic Stainless SteelP - ForgingAp - EnergyCd - Brittle Behavior
Cm - As polished micrographyDf - Corrosion
Micrographic detail of a transverse section of the ring, showing the corroded martensitic structure (chemical dissolution) inside the pitting.
32
VIEW
ML00124 / Feb.2018
MIC of a Martensitic Valve Ring
M - Martensitic Stainless SteelP - ForgingAp - EnergyCd - Brittle Behavior
Cm - As polished micrographyDf - Corrosion
Micrographic detail of a transverse section of the ring, showing the corroded martensitic structure (chemical dissolution) inside the pitting.
33
VIEW
ML00124 / Feb.2018
MIC of a Martensitic Valve Ring
M - Martensitic Stainless SteelP - ForgingAp - EnergyCd - Brittle Behavior
Cm - As polished micrographyDf - Intergranular Cracking
Micrography of a transverse section of the ring at the cracking position. The cracks are intergranular and opened at the position close to the surface.
27
VIEW
ML00124 / Feb.2018
MIC of a Martensitic Valve Ring
M - Martensitic Stainless SteelP - ForgingAp - EnergyCd - Brittle Behavior
Cm - Kalling Etched Micrography by OMDf - Martensite
Micrography of a transverse section of the ring at the cracking position. The cracks are intergranular and opened at the position close to the surface. it is possible to identify dissolution of the structure adjacent to the grain boundaries,
25
VIEW
ML00124 / Feb.2018
MIC of a Martensitic Valve Ring
M - Martensitic Stainless SteelP - ForgingAp - EnergyCd - Brittle Behavior
Cm - Kalling Etched Micrography by OMDf - Crack

+4 more from this case →