Optical Microscope

12 cases · 144 images

Crevice Corrosion in a Subsea System — Aspect Before Analysis

Application: Ship Condition: Damage clear all

Optical Microscope — sub-branches

As polished micrography 28FeCl3+HCl+Ethanol Etched Micro 7FeCl3+HCl+H2O Etched Micro 7Kalling Etched Micrography by OM 11Micrography by OM 1NaOH Electrolytic Etched Micro 11Nital Etched Micrography by OM 79

Results

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Micrography of the tooth gear, in a transverse section, close to surface. The material presents light ghost marks that reveal chemical segregations.
80
VIEW
ML00181 / Apr.2022
Wear of a Carburized Hypoid Gear
M - Low Alloy for Thermochemical TreatmentP - Pinion-crown assemblyAp - ShipCd - Wear
Cm - Nital Etched Micrography by OMDf - At the Surface
Micrography of a transverse section of the spring, at the surface showing pits full of deposits.
36
VIEW
ML00172 / Mar.2021
Brittle Fracture of a LAS Valve Spring
M - Low Alloy Medium Carbon QTP - SpringAp - Oil and GasCd - Brittle Fracture
Cm - Nital Etched Micrography by OMDf - Transverse Section
Metallographic image of a longitudinal section of the clamp (axis in the vertical direction), showing a refined ferritic perlitic structure.
34
VIEW
ML00171 / Feb.2021
Corrosion Fatigue of U Bolt Pipe Clamp
M - Low Carbon SteelP - BoltAp - ShipCd - Corrosion Fatigue
Cm - Nital Etched Micrography by OMDf - Longitudinal Section
Micrography of the tranverse section of the tube, in the center of the thickness. There are small grains and large grains, characterizing a dual grain size. The large grains size is about 100 microns, more than 10 times larger than the average size of the smaller grains size.
101
VIEW
ML00165 / Jul.2020
SCC of Aluminum Bronze Heating Coil
M - Aluminum BronzeP - Seamless tubeAp - Oil and GasCd - Stress Corrosion
Cm - FeCl3+HCl+H2O Etched MicroDf - Dual grain sizes
Micrography of a longitudinal section of the sleeve, at the external surface where there are two layers of coating. The electrolytic etch evidenced the duplex stainless steel substrate (bottom of the figure) and the weave interface of the substrate and the first thermal spray layer, about 1 mm thick, in a stainless steel. The surface layer, of tugnsten carbide, about 0.2 mm thick, is black and not clearly visible in this figure.
50
VIEW
ML00147 / Aug.2018
WC Layer Detached from a Cast Lean Duplex
M - Lean Duplex Stainless SteelP - Centrifugal CastingAp - ShipCd - Lack of Sealing
Cm - NaOH Electrolytic Etched MicroDf - External Surface
Micrographic aspect, as polished, of the cast cylinder section at the fracture position (top of the figure), close to the internal surface (left side). It is possible to see large graphite flakes.
98
VIEW
ML00141 / Jul.2018
Brittle Fracture of a Corroded Gray Cast Iron
M - Gray Cast ironP - CastingAp - EngineCd - Brittle Fracture
Cm - As polished micrographyDf - Close to the Internal Surface
Micrography of the pipe transverse section presenting a granular microstructure.
147
VIEW
ML00140 / May.2019
Preferential Corrosion of Pipe Seam Weld
M - Low Carbon SteelP - Longitudinal Seam Welded PipeAp - ShipCd - Preferential Dissolution
Cm - Nital Etched Micrography by OMDf - Transverse Section
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

More from these cases

ML00181 — Wear of a Carburized Hypoid GearM - Low Alloy for Thermochemical TreatmentP - Pinion-crown assemblyAp - ShipCd - Wear
Micrographic detail of the case hardened martensitic structure, close to the surface, with a microhardness level of about 600 Vickers (load 0.3kg).
70
VIEW
ML00181 / Apr.2022
Wear of a Carburized Hypoid Gear
M - Low Alloy for Thermochemical TreatmentP - Pinion-crown assemblyAp - ShipCd - Wear
Cm - Nital Etched Micrography by OMDf - Martensite
Micrography of the tooth gear, in a transverse section of center region. Again, some segregation patterns are visible.
58
VIEW
ML00181 / Apr.2022
Wear of a Carburized Hypoid Gear
M - Low Alloy for Thermochemical TreatmentP - Pinion-crown assemblyAp - ShipCd - Wear
Cm - Nital Etched Micrography by OMDf - In the Center of the Thickness
Micrography of the core structure, in the center of layer, with a microhardness level of about 220 Vickers (load 0.3kg).
58
VIEW
ML00181 / Apr.2022
Wear of a Carburized Hypoid Gear
M - Low Alloy for Thermochemical TreatmentP - Pinion-crown assemblyAp - ShipCd - Wear
Cm - Nital Etched Micrography by OMDf - Bainitic Martensitic
Micrographic detail of the fractured region transverse to the tooth. Secondary parallel cracks propagating in the tooth structure, tyypical of contact fatigue.
38
VIEW
ML00181 / Apr.2022
Wear of a Carburized Hypoid Gear
M - Low Alloy for Thermochemical TreatmentP - Pinion-crown assemblyAp - ShipCd - Wear
Cm - Nital Etched Micrography by OMDf - Secondary Cracks
Wear of a Carburized Hypoid Gear
3
VIEW
ML00181 / Apr.2022
Wear of a Carburized Hypoid Gear
M - Low Alloy for Thermochemical TreatmentP - Pinion-crown assemblyAp - ShipCd - Wear
Cm - Nital Etched Micrography by OMDf - Bainitic Martensitic
ML00172 — Brittle Fracture of a LAS Valve SpringM - Low Alloy Medium Carbon QTP - SpringAp - Oil and GasCd - Brittle Fracture
Micrographic detail of the transverse section of the spring, at the surface, showing the pits full of corrosion deposits.
31
VIEW
ML00172 / Mar.2021
Brittle Fracture of a LAS Valve Spring
M - Low Alloy Medium Carbon QTP - SpringAp - Oil and GasCd - Brittle Fracture
Cm - Nital Etched Micrography by OMDf - Surface Deposits
Micrographic detail of spring surface, showing the pits full of corrosion deposits and a small decarburized layer (probably from the manufacturing processes).
30
VIEW
ML00172 / Mar.2021
Brittle Fracture of a LAS Valve Spring
M - Low Alloy Medium Carbon QTP - SpringAp - Oil and GasCd - Brittle Fracture
Cm - Nital Etched Micrography by OMDf - Decarburized Surface
Micrography of a longitudinal section of the spring, at the surface, indicating that there are multiple intergranular cracks initiating from the pit.
26
VIEW
ML00172 / Mar.2021
Brittle Fracture of a LAS Valve Spring
M - Low Alloy Medium Carbon QTP - SpringAp - Oil and GasCd - Brittle Fracture
Cm - As polished micrographyDf - Multiple cracks
Micrographic aspect of the multiple intergranular cracks, initiating from the bottom of a pit.
25
VIEW
ML00172 / Mar.2021
Brittle Fracture of a LAS Valve Spring
M - Low Alloy Medium Carbon QTP - SpringAp - Oil and GasCd - Brittle Fracture
Cm - As polished micrographyDf - Intergranular Cracking
Micrographic detail of the intergranular cracks, initiating from the bottom of a pit.
29
VIEW
ML00172 / Mar.2021
Brittle Fracture of a LAS Valve Spring
M - Low Alloy Medium Carbon QTP - SpringAp - Oil and GasCd - Brittle Fracture
Cm - As polished micrographyDf - Intergranular Cracking

+3 more from this case →

ML00171 — Corrosion Fatigue of U Bolt Pipe ClampM - Low Carbon SteelP - BoltAp - ShipCd - Corrosion Fatigue
Metallographic detail of the longitudinal section of the clamp with a ferritic pearlitic structure.
32
VIEW
ML00171 / Feb.2021
Corrosion Fatigue of U Bolt Pipe Clamp
M - Low Carbon SteelP - BoltAp - ShipCd - Corrosion Fatigue
Cm - Nital Etched Micrography by OMDf - Ferrite and Pearlite
Metallographic detail of the ferritic perlitic structure.
31
VIEW
ML00171 / Feb.2021
Corrosion Fatigue of U Bolt Pipe Clamp
M - Low Carbon SteelP - BoltAp - ShipCd - Corrosion Fatigue
Cm - Nital Etched Micrography by OMDf - Ferrite and Pearlite
Metallographic aspect of a longitudinal section of the clamp, at the surface (left side of the image) showing a region where there are corrosion pits in the carbon steel clamp, due to the lack of protection by the coating, and the propagation of small transgranular cracks from to the surface.
30
VIEW
ML00171 / Feb.2021
Corrosion Fatigue of U Bolt Pipe Clamp
M - Low Carbon SteelP - BoltAp - ShipCd - Corrosion Fatigue
Cm - Micrography by OMDf - Crack
The clamp presented several cracks, parallel, transverse to the axis. The appearance of the cracks in the metallographic section shows that some cracks propagate and growth with a irregular path.
24
VIEW
ML00171 / Feb.2021
Corrosion Fatigue of U Bolt Pipe Clamp
M - Low Carbon SteelP - BoltAp - ShipCd - Corrosion Fatigue
Cm - Nital Etched Micrography by OMDf - Longitudinal Section
Metallographic aspect of the cracks showing that several microcracks join from different pits and growth through the section, in a transgranular morphologyy.
26
VIEW
ML00171 / Feb.2021
Corrosion Fatigue of U Bolt Pipe Clamp
M - Low Carbon SteelP - BoltAp - ShipCd - Corrosion Fatigue
Cm - Nital Etched Micrography by OMDf - Transgranular Cracking

+2 more from this case →

ML00165 — SCC of Aluminum Bronze Heating CoilM - Aluminum BronzeP - Seamless tubeAp - Oil and GasCd - Stress Corrosion
Micrographic detail of the alpha microstructure presenting dual grain sizes. Two different types of twins are presented in the structure: annealing twins and deformation twins, suggesting that the material was probably partially recristalized after cold deformation and stress relief treatment.
87
VIEW
ML00165 / Jul.2020
SCC of Aluminum Bronze Heating Coil
M - Aluminum BronzeP - Seamless tubeAp - Oil and GasCd - Stress Corrosion
Cm - FeCl3+HCl+H2O Etched MicroDf - Alpha
Micrography of a transverse section of the bent tube, external surface (OD) to the top and internal surface (ID) to the bottom of the figure. At the through wall cracking position, the external surface presented a layer of intergranular corrosion.
95
VIEW
ML00165 / Jul.2020
SCC of Aluminum Bronze Heating Coil
M - Aluminum BronzeP - Seamless tubeAp - Oil and GasCd - Stress Corrosion
Cm - As polished micrographyDf - Cracking
Micrographic detail of the external side of the bent tube, as polished, showing detachement of several grains due to the intergranular corrosion layer. The corroded layer is about 200 microns thick at this position.
89
VIEW
ML00165 / Jul.2020
SCC of Aluminum Bronze Heating Coil
M - Aluminum BronzeP - Seamless tubeAp - Oil and GasCd - Stress Corrosion
Cm - As polished micrographyDf - Intergranular Corrosion
Micrographic detail of the external side of the tube, showing the layer of intergranular corrosion and the through ewall integranular stress corrosion cracking.
88
VIEW
ML00165 / Jul.2020
SCC of Aluminum Bronze Heating Coil
M - Aluminum BronzeP - Seamless tubeAp - Oil and GasCd - Stress Corrosion
Cm - As polished micrographyDf - Through Wall Cracking
Micrography of the external side of the bent tube, showing detachement of several grains due to intergranular corrosion. The corroded layer is about 200 microns thick at this position. The differences of colours in the corroded layer suggests a dealloying effect, also known as selective leaching.
71
VIEW
ML00165 / Jul.2020
SCC of Aluminum Bronze Heating Coil
M - Aluminum BronzeP - Seamless tubeAp - Oil and GasCd - Stress Corrosion
Cm - FeCl3+HCl+H2O Etched MicroDf - External Surface

+4 more from this case →

ML00147 — WC Layer Detached from a Cast Lean DuplexM - Lean Duplex Stainless SteelP - Centrifugal CastingAp - ShipCd - Lack of Sealing
Micrography of a longitudinal section of the sleeve close to the external surface, evidencing a tugnsten carbide thermal spray layer, thickness about 0.2 mm, at the sleeve outer diameter (OD), black due to the etch (top of the figure). This WC layer was deposited over a stainless steel layer disposed in several layers, non etched.
42
VIEW
ML00147 / Aug.2018
WC Layer Detached from a Cast Lean Duplex
M - Lean Duplex Stainless SteelP - Centrifugal CastingAp - ShipCd - Lack of Sealing
Cm - NaOH Electrolytic Etched MicroDf - Thermal Spray Layer
Micrographic detail of the interface between the two thermal spray layers, the first one in stainless steel (bottom of the figure) and the second one, at the surface,in tungsten carbide (top of the figure). The micrographic sample is etched and that is why the WC is dark (black) and the stainless steel is light (non etched).
41
VIEW
ML00147 / Aug.2018
WC Layer Detached from a Cast Lean Duplex
M - Lean Duplex Stainless SteelP - Centrifugal CastingAp - ShipCd - Lack of Sealing
Cm - NaOH Electrolytic Etched MicroDf - Thermal Spray Layer
Micrography of the longitudinal section of the sleeve, at the interface between the substrate and the first thermal spray layer. The substrate (bottom of the figure) shows a ferritic-austenitic microstructure and detrimental phases that look like sigma. The thermal spray layer (top of the figure) presents the non-etched stainless steel, disposed in layers, with oxides (gray) and voids (black). The substrate is deformed in a thin layer at the interface.
38
VIEW
ML00147 / Aug.2018
WC Layer Detached from a Cast Lean Duplex
M - Lean Duplex Stainless SteelP - Centrifugal CastingAp - ShipCd - Lack of Sealing
Cm - NaOH Electrolytic Etched MicroDf - Close to the External Surface
Micrographic detail of the interface between the substrate and the first thermal spray layer. The substrate (bottom of the figure) shows a ferritic-austenitic microstructure and detrimental phases that look like sigma at the delta and gamma interface. The thermal spray layer (top of the figure) presents the non-etched stainless steel, disposed in layers, with oxides (gray) and voids (black). The substrate is deformed in a thin layer at the interface.
34
VIEW
ML00147 / Aug.2018
WC Layer Detached from a Cast Lean Duplex
M - Lean Duplex Stainless SteelP - Centrifugal CastingAp - ShipCd - Lack of Sealing
Cm - NaOH Electrolytic Etched MicroDf - Sigma
Micrography of the longitudinal section of the cast sleeve in the middle of the thickness. The microstructure is coarse, austenitic ferritic.
34
VIEW
ML00147 / Aug.2018
WC Layer Detached from a Cast Lean Duplex
M - Lean Duplex Stainless SteelP - Centrifugal CastingAp - ShipCd - Lack of Sealing
Cm - NaOH Electrolytic Etched MicroDf - In the Center of the Thickness

+12 more from this case →

ML00141 — Brittle Fracture of a Corroded Gray Cast IronM - Gray Cast ironP - CastingAp - EngineCd - Brittle Fracture
Micrographic aspect, as polished, of the cast cylinder section at the fracture position (top of the figure), in the center of the thickness. It is possible to see a mixture of large graphite flakes and rosette grouping flakes.
80
VIEW
ML00141 / Jul.2018
Brittle Fracture of a Corroded Gray Cast Iron
M - Gray Cast ironP - CastingAp - EngineCd - Brittle Fracture
Cm - As polished micrographyDf - In the Center of the Thickness
Micrographic aspect, as polished, of the cast cylinder section at the fracture position (top of the figure), close to the external surface (left side). It is possible to see smaller graphite flakes, interdendritic .
79
VIEW
ML00141 / Jul.2018
Brittle Fracture of a Corroded Gray Cast Iron
M - Gray Cast ironP - CastingAp - EngineCd - Brittle Fracture
Cm - As polished micrographyDf - Close to the External Surface
Micrography of the longitudinal section of the cylinder, at the internal diameter (left side of the figure), in contact with the treated cooling water, presenting large graphite flakes in a predominatly perlitic matrix.
50
VIEW
ML00141 / Jul.2018
Brittle Fracture of a Corroded Gray Cast Iron
M - Gray Cast ironP - CastingAp - EngineCd - Brittle Fracture
Cm - Nital Etched Micrography by OMDf - Close to the Internal Surface
Micrography of the longitudinal section of the cylinder, at the internal diameter, in contact with the treated cooling water, presenting large graphite flakes in a predominatly perlitic matrix. It is important to mention that the flakes are almost interconnecting themelves.
47
VIEW
ML00141 / Jul.2018
Brittle Fracture of a Corroded Gray Cast Iron
M - Gray Cast ironP - CastingAp - EngineCd - Brittle Fracture
Cm - Nital Etched Micrography by OMDf - Graphite in Flakes
Micrography of the longitudinal section of the cylinder, at the internal diameter, in contact with the treated cooling water, presenting large graphite flakes in a predominatly perlitic matrix. It is important to mention that the flakes are almost interconnecting themelves.
48
VIEW
ML00141 / Jul.2018
Brittle Fracture of a Corroded Gray Cast Iron
M - Gray Cast ironP - CastingAp - EngineCd - Brittle Fracture
Cm - Nital Etched Micrography by OMDf - Predominantly Pearlitic

+19 more from this case →

ML00140 — Preferential Corrosion of Pipe Seam WeldM - Low Carbon SteelP - Longitudinal Seam Welded PipeAp - ShipCd - Preferential Dissolution
Micrography of the pipe transverse section presenting a predominatly ferritic-perlitic microstructure.
132
VIEW
ML00140 / May.2019
Preferential Corrosion of Pipe Seam Weld
M - Low Carbon SteelP - Longitudinal Seam Welded PipeAp - ShipCd - Preferential Dissolution
Cm - Nital Etched Micrography by OMDf - Ferrite and Pearlite
Micrographic detail of the predominatly ferritic-perlitic microstructure. Pipe transverse section.
95
VIEW
ML00140 / May.2019
Preferential Corrosion of Pipe Seam Weld
M - Low Carbon SteelP - Longitudinal Seam Welded PipeAp - ShipCd - Preferential Dissolution
Cm - Nital Etched Micrography by OMDf - Ferrite and Pearlite
Micrography of the pipe in the leakage area, showing the preferential corrosion in the center of the autogenous weld and oxides inside the crevice, that appearas as a cracking but that is only a localized anodic process.
66
VIEW
ML00140 / May.2019
Preferential Corrosion of Pipe Seam Weld
M - Low Carbon SteelP - Longitudinal Seam Welded PipeAp - ShipCd - Preferential Dissolution
Cm - Nital Etched Micrography by OMDf - Localized Corrosion
Micrographic detail of the autogenous seam weld. The localized dissolution occurrs exactly at the weld metal that presents a bainitic structure of average hardness about 230HV, compared to the heat affected zone presenting average of 202 HV and the base metal presenting average of 180HV.
57
VIEW
ML00140 / May.2019
Preferential Corrosion of Pipe Seam Weld
M - Low Carbon SteelP - Longitudinal Seam Welded PipeAp - ShipCd - Preferential Dissolution
Cm - Nital Etched Micrography by OMDf - Localized Corrosion
Micrographic detail presenting the slighltly decarburized ferritic structure, with inclusions, in the center of the weld, surrounded by a bainitic structure and the preferential corrosion in the weld.
51
VIEW
ML00140 / May.2019
Preferential Corrosion of Pipe Seam Weld
M - Low Carbon SteelP - Longitudinal Seam Welded PipeAp - ShipCd - Preferential Dissolution
Cm - Nital Etched Micrography by OMDf - Localized Corrosion

+5 more from this case →

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 →