Microstructure

16 cases · 59 images

Crevice Corrosion in a Subsea System — Aspect Before Analysis

Application: Ship Capture method: Optical Microscope clear all

Microstructure — sub-branches

Alpha 1Alpha and Beta 3Bainitic HAZ 2Bainitic Martensitic 2Banded Pearlite 2Banded Structure 2Coalesced structure 2Decarburized Surface 1Dendritic 3Dual grain sizes 1Duplex structure 2Ferrite and Pearlite 11Ferritic Weld Metal 2Grain boundary intermetallics 2Grain refined structure 1Graphite in Flakes 2Graphite in Nodules 1Martensite 4Non Metallic Inclusions 1Predominantly Ferritic 2Predominantly Pearlitic 2Sigma 3Strain Hardened 2Thermal Spray Layer 5

Results

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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
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
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
Low magnification micrography of a transverse section of the ring showing a dendritic structure.
64
VIEW
ML00166 / Jul.2020
Tin Bronze Wear Ring of Seawater Pump
M - Tin BronzeP - Wear RingAp - ShipCd - Removed From Service
Cm - FeCl3+HCl+H2O Etched MicroDf - Dendritic
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 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
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 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

More from these cases

ML00181 — Wear of a Carburized Hypoid GearM - Low Alloy for Thermochemical TreatmentP - Pinion-crown assemblyAp - ShipCd - Wear
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
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 wire, martensitic.
24
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 - Martensite
Micrographic detail of the martensitic structure, uniform through thickness.
17
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 - Martensite
ML00171 — Corrosion Fatigue of U Bolt Pipe ClampM - Low Carbon SteelP - BoltAp - ShipCd - Corrosion Fatigue
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
ML00166 — Tin Bronze Wear Ring of Seawater PumpM - Tin BronzeP - Wear RingAp - ShipCd - Removed From Service
Micrography of a transverse section of the ring showing a cored alpha structure with segregation at interdendritic regions. This structure is in a region close to the ring surface.
52
VIEW
ML00166 / Jul.2020
Tin Bronze Wear Ring of Seawater Pump
M - Tin BronzeP - Wear RingAp - ShipCd - Removed From Service
Cm - FeCl3+HCl+H2O Etched MicroDf - Dendritic
Micrography of a transverse section of the ring showing a cored alpha structure with strong segregation at interdendritic regions, and regions of a white structure at grain boundaries. This structure is in a region close to the center of the ring.
51
VIEW
ML00166 / Jul.2020
Tin Bronze Wear Ring of Seawater Pump
M - Tin BronzeP - Wear RingAp - ShipCd - Removed From Service
Cm - FeCl3+HCl+H2O Etched MicroDf - Dendritic
Micrographic detail of the cored alpha structure with light segregation at intergranular regions (light layer at grain boundaries), and a white euctetoid structure (alpha and delta) at interdendritic space. This structure is in a region close to the ring surface, where the solidification was quicker.
49
VIEW
ML00166 / Jul.2020
Tin Bronze Wear Ring of Seawater Pump
M - Tin BronzeP - Wear RingAp - ShipCd - Removed From Service
Cm - FeCl3+HCl+H2O Etched MicroDf - Grain boundary intermetallics
Micrographic detail of the cored alpha structure with strong segregation at intergranular regions (dark layer at grain boundaries), and a white euctetoid structure (alpha and delta) at interdendritic space. This structure is in a region close to the center of the ring, where the solidification was slower.
47
VIEW
ML00166 / Jul.2020
Tin Bronze Wear Ring of Seawater Pump
M - Tin BronzeP - Wear RingAp - ShipCd - Removed From Service
Cm - FeCl3+HCl+H2O Etched MicroDf - Grain boundary intermetallics
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
ML00147 — WC Layer Detached from a Cast Lean DuplexM - Lean Duplex Stainless SteelP - Centrifugal CastingAp - ShipCd - Lack of Sealing
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
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 duplex, austenitic and ferritic. The etch presents different colours for the phases. The yellow is associated to detrimental phases, like sigma, at the ferritic phase (ligh blue) and the white phase is the austenite.
36
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 - Duplex structure
Micrographic detail of the longitudinal section of the cast sleeve in the middle of the thickness. The microstructure is duplex, austenitic and ferritic. The etch presents different colours for the phases. The yellow is associated to detrimental phases, like sigma, at the ferritic phase (ligh blue) and the white phase is the austenite.
30
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 at the ID. The microstructure is duplex, austenitic and ferritic. The etch presents different colours for the phases. The yellow is associated to detrimental phases, like sigma, at the ferritic phase (ligh blue) and the white phase is the austenite.
21
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 - Duplex structure

+4 more from this case →

ML00141 — Brittle Fracture of a Corroded Gray Cast IronM - Gray Cast ironP - CastingAp - EngineCd - Brittle Fracture
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
Micrography of the longitudinal section of the cylinder, in the center of the thickness, presenting large graphite flakes in a predominatly perlitic matrix. There are also ferritic regions.
33
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, in the center of the thickness, presenting large graphite flakes in a predominatly pearlitic matrix.
31
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
Micrography of the longitudinal section of the cylinder, at the external diameter (right side of the figure), presenting smaller interdendritic graphite flakes in a ferritic-perlitic matrix. It is also possible to see free carbides (cementite) very close to the cylinder surface (less than 50 microns), associated to positions of graphite. This surface was painted.
25
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 - Ferrite and Pearlite
ML00140 — Preferential Corrosion of Pipe Seam WeldM - Low Carbon SteelP - Longitudinal Seam Welded PipeAp - ShipCd - Preferential Dissolution
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