Optical Microscope

41 cases · 176 images

Crevice Corrosion in a Subsea System — Aspect Before Analysis

Condition: Damage Standard: A Detail focus: Damage clear all

Optical Microscope — sub-branches

As polished micrography 22Kalling Etched Micrography by OM 12Micrography by OM 14Micrography by OM using A262 Method A 11NaOH Electrolytic Etched Micro 12Nital Etched Micrography by OM 100Oxalic Acid Electrolytic Etch 5

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Micrography of the thread at the valve body surface, showing localized dissolution of the thread.
73
VIEW
ML00184 / Apr.2023
Dissimilar Steels in a Threaded Connection
M - Low Carbon SteelP - ForgingAp - OffshoreCd - Localized Dissolution
Cm - Nital Etched Micrography by OMDf - Corroded Thread
WELD METAL SURFACE
43
VIEW
ML00177 / Dec.2021
Cr-Mo Seam Welded Tube
M - CrMo SteelP - Longitudinally Seam WeldedAp - Fired HeaterCd - Not according to spec
Cm - Nital Etched Micrography by OMDf - Segregated Regions
Metallographic detail of the wire surface in one strand external wire, showing the presence of oxides.
39
VIEW
ML00175 / Aug.2021
Localized External Wear of a Wire Rope
M - High Carbon SteelP - Wire RopeAp - Oil and GasCd - Wear
Cm - Nital Etched Micrography by OMDf - Oxide Layer
Cast fitting microstructure. The material presented a network of primary carbided and an austenitic matrix with coalescing secondary precipitation.
37
VIEW
ML00173 / May.2021
Welding Cracks in an Aged HP Cast Fitting
M - Heat Resistant SteelP - Cast FtittingAp - PetrochemicalCd - Welding
Cm - Kalling Etched Micrography by OMDf - Aged Microstructure
Optical micrography of a longitudinal section of the fractured bolt, at the thread. The material is austenitic, free from carbides, and the threads were almost removed by the stress corrosion cracks.
756
VIEW
ML00157 / Feb.2020
Bolts Under Chloride SCC Conditions
M - Austenitic Stainless SteelP - BoltAp - Oil and GasCd - Stress Corrosion
Cm - Oxalic Acid Electrolytic EtchDf - Stress Corrosion Cracks
Large pore in the weld metal, that did not influence in the failure.
59
VIEW
ML00150 / Dec.2018
Vibration Induced Fatigue in a SS Oil Piping
M - Duplex Stainless SteelP - PipingAp - FPSOCd - Vibration Induced Fatigue
Cm - NaOH Electrolytic Etched MicroDf - Pore
Micrography showing the cracking starting point, in the pipe, exactly at the margin of the weld.
292
VIEW
ML00149 / Dec.2018
Vibration Induced Fatigue in a Gas Piping
M - Low Carbon SteelP - Piping spoolAp - FPSOCd - Vibration Induced Fatigue
Cm - Nital Etched Micrography by OMDf - Margin of the Weld Crack
Micrography of the nut in the longitudinal section, plastic deformation at the thread surface due to high local stresses, probably during assembling.
24
VIEW
ML00148 / Sep.2018
Brittle Fracture of a 420 SS Barrel Nut
M - Martensitic Stainless SteelP - Barrel NutAp - LiftingCd - Heat Treatment Defect
Cm - Kalling Etched Micrography by OMDf - Plastic Deformation

More from these cases

ML00184 — Dissimilar Steels in a Threaded ConnectionM - Low Carbon SteelP - ForgingAp - OffshoreCd - Localized Dissolution
Micrography of the valve body carbon steel thread, in the peak. Ferritic-bainitic structure.
64
VIEW
ML00184 / Apr.2023
Dissimilar Steels in a Threaded Connection
M - Low Carbon SteelP - ForgingAp - OffshoreCd - Localized Dissolution
Cm - Nital Etched Micrography by OMDf - Corroded Thread
Micrographic detail of the valve body carbon steel thread, in the peak. Ferritic-bainitic structure.
55
VIEW
ML00184 / Apr.2023
Dissimilar Steels in a Threaded Connection
M - Low Carbon SteelP - ForgingAp - OffshoreCd - Localized Dissolution
Cm - Nital Etched Micrography by OMDf - Corroded Thread
Cross-section near a threaded surface showing an acicular matrix structure bordered by a dark, layered corrosion/oxide band along the thread root.
1
VIEW
ML00184 / Apr.2023
Dissimilar Steels in a Threaded Connection
M - Low Carbon SteelP - ForgingAp - OffshoreCd - Localized Dissolution
Cm - Nital Etched Micrography by OMDf - Oxide Layer
ML00177 — Cr-Mo Seam Welded TubeM - CrMo SteelP - Longitudinally Seam WeldedAp - Fired HeaterCd - Not according to spec
WELD METAL T/2
31
VIEW
ML00177 / Dec.2021
Cr-Mo Seam Welded Tube
M - CrMo SteelP - Longitudinally Seam WeldedAp - Fired HeaterCd - Not according to spec
Cm - Nital Etched Micrography by OMDf - Segregated Regions
ML00173 — Welding Cracks in an Aged HP Cast FittingM - Heat Resistant SteelP - Cast FtittingAp - PetrochemicalCd - Welding
Micrographic detail of the network of primary carbided, white and grey, and an austenitic matrix with coalescing secondary precipitation.
30
VIEW
ML00173 / May.2021
Welding Cracks in an Aged HP Cast Fitting
M - Heat Resistant SteelP - Cast FtittingAp - PetrochemicalCd - Welding
Cm - Kalling Etched Micrography by OMDf - Aged Microstructure
Micrographic detail of the cracks at the fusion line, associated to the partially melted region suggesting a liquation effect in a material that presented low ductility. After opening the cracks they propagate brittle into the base metal and created a solidification cracking in the weld metal, detailed in the next figures.
23
VIEW
ML00173 / May.2021
Welding Cracks in an Aged HP Cast Fitting
M - Heat Resistant SteelP - Cast FtittingAp - PetrochemicalCd - Welding
Cm - Kalling Etched Micrography by OMDf - Multiple cracks
Micrographic detail of the cracks in the base metal created from the partially melted region suggesting that a liquation effect propagated brittle cracks into the low ductility base metal.
30
VIEW
ML00173 / May.2021
Welding Cracks in an Aged HP Cast Fitting
M - Heat Resistant SteelP - Cast FtittingAp - PetrochemicalCd - Welding
Cm - Kalling Etched Micrography by OMDf - Cracks
ML00157 — Bolts Under Chloride SCC ConditionsM - Austenitic Stainless SteelP - BoltAp - Oil and GasCd - Stress Corrosion
Optical micrography of a longitudinal section of the fractured bolt, at the thread. The material is austenitic, free from carbides, and the threads were fully cracked by the stress corrosion mechanism.
58
VIEW
ML00157 / Feb.2020
Bolts Under Chloride SCC Conditions
M - Austenitic Stainless SteelP - BoltAp - Oil and GasCd - Stress Corrosion
Cm - Oxalic Acid Electrolytic EtchDf - Stress Corrosion Cracks
Optical micrography of a longitudinal section of the fractured bolt, under the thread, showing stress corrosion cracks through the section.
46
VIEW
ML00157 / Feb.2020
Bolts Under Chloride SCC Conditions
M - Austenitic Stainless SteelP - BoltAp - Oil and GasCd - Stress Corrosion
Cm - Oxalic Acid Electrolytic EtchDf - Stress Corrosion Cracks
Detailed aspect of the stress corrosion cracks in a longitudinal section of the fractured bolt, under the thread. The microstructure is strain hardened austenite.
47
VIEW
ML00157 / Feb.2020
Bolts Under Chloride SCC Conditions
M - Austenitic Stainless SteelP - BoltAp - Oil and GasCd - Stress Corrosion
Cm - Oxalic Acid Electrolytic EtchDf - Stress Corrosion Cracks
Detailed aspect of the brached transgranular stress corrosion cracks, in a longitudinal section of the fractured bolt. The microstructure is strain hardened austenite.
40
VIEW
ML00157 / Feb.2020
Bolts Under Chloride SCC Conditions
M - Austenitic Stainless SteelP - BoltAp - Oil and GasCd - Stress Corrosion
Cm - Oxalic Acid Electrolytic EtchDf - Stress Corrosion Cracks
ML00150 — Vibration Induced Fatigue in a SS Oil PipingM - Duplex Stainless SteelP - PipingAp - FPSOCd - Vibration Induced Fatigue
Micrography of the fatigue crack propagating in the pipe thickness. Fully flat and not influenced by any microstructure.
52
VIEW
ML00150 / Dec.2018
Vibration Induced Fatigue in a SS Oil Piping
M - Duplex Stainless SteelP - PipingAp - FPSOCd - Vibration Induced Fatigue
Cm - NaOH Electrolytic Etched MicroDf - Fatigue Crack
Micrography of the fatigue crack close to the internal wall, where (only) the final through wall rupture is associated to plastic deformation, as detailed in the next figure.
56
VIEW
ML00150 / Dec.2018
Vibration Induced Fatigue in a SS Oil Piping
M - Duplex Stainless SteelP - PipingAp - FPSOCd - Vibration Induced Fatigue
Cm - NaOH Electrolytic Etched MicroDf - Fatigue Crack
Micrographic detail of the final crack propagation through wall, with plastic deformation.
62
VIEW
ML00150 / Dec.2018
Vibration Induced Fatigue in a SS Oil Piping
M - Duplex Stainless SteelP - PipingAp - FPSOCd - Vibration Induced Fatigue
Cm - NaOH Electrolytic Etched MicroDf - Plastic Deformation
ML00149 — Vibration Induced Fatigue in a Gas PipingM - Low Carbon SteelP - Piping spoolAp - FPSOCd - Vibration Induced Fatigue
Micrographic detail of the cracking starting point, in the pipe, exactly at the margin of the weld.
33
VIEW
ML00149 / Dec.2018
Vibration Induced Fatigue in a Gas Piping
M - Low Carbon SteelP - Piping spoolAp - FPSOCd - Vibration Induced Fatigue
Cm - Nital Etched Micrography by OMDf - Fatigue Crack
Micrography of a section tranverse to the pipe and to the weld between the 8"pipe and the 2" fitting weldolet. The crack starts exactly at the margin of the weld and propagates in the pipe longitudinal direction, in a straight line, not related to any metallurgical aspect.
30
VIEW
ML00149 / Dec.2018
Vibration Induced Fatigue in a Gas Piping
M - Low Carbon SteelP - Piping spoolAp - FPSOCd - Vibration Induced Fatigue
Cm - Micrography by OMDf - Cracking
Micrographic detail of the fatigue crack propagation in the pipe longitudinal direction, in a straight line, not related to any metallurgical aspect.
29
VIEW
ML00149 / Dec.2018
Vibration Induced Fatigue in a Gas Piping
M - Low Carbon SteelP - Piping spoolAp - FPSOCd - Vibration Induced Fatigue
Cm - Micrography by OMDf - Fatigue Crack
Micrography of a section tranverse to the pipe and to the weld between the 8"pipe and the 2" fitting weldolet. The crack starts exactly at the margin of the weld and propagates in the pipe longitudinal direction, in a straight line until it reaches the condition of overloading and through wall final rupture, with strong plastic deformation as can be seen around the crack.
25
VIEW
ML00149 / Dec.2018
Vibration Induced Fatigue in a Gas Piping
M - Low Carbon SteelP - Piping spoolAp - FPSOCd - Vibration Induced Fatigue
Cm - Nital Etched Micrography by OMDf - Plastic Deformation
Micrographic detail of the final fracture by overloading after the fatigue crack propagated almost through the wall thickness. The microstructure presents strong plastic deformation around the crack, in a ferritic pearlitic structure.
29
VIEW
ML00149 / Dec.2018
Vibration Induced Fatigue in a Gas Piping
M - Low Carbon SteelP - Piping spoolAp - FPSOCd - Vibration Induced Fatigue
Cm - Nital Etched Micrography by OMDf - Ductile Fracture
ML00148 — Brittle Fracture of a 420 SS Barrel NutM - Martensitic Stainless SteelP - Barrel NutAp - LiftingCd - Heat Treatment Defect
Micrographic detail of the nut in the longitudinal section, presenting cracks associated to the plastic deformation at the thread surface. These cracks were formed due to high local contact stresses.
19
VIEW
ML00148 / Sep.2018
Brittle Fracture of a 420 SS Barrel Nut
M - Martensitic Stainless SteelP - Barrel NutAp - LiftingCd - Heat Treatment Defect
Cm - Kalling Etched Micrography by OMDf - Plastic Deformation
Micrographic detail of the nut in the longitudinal section, presenting cracks associated to the plastic deformation at the thread surface. These cracks were formed due to high local contact stresses.
17
VIEW
ML00148 / Sep.2018
Brittle Fracture of a 420 SS Barrel Nut
M - Martensitic Stainless SteelP - Barrel NutAp - LiftingCd - Heat Treatment Defect
Cm - Kalling Etched Micrography by OMDf - Cracks
Micrography of the nut in the longitudinal section, transverse to the fracture (top of the image).
15
VIEW
ML00148 / Sep.2018
Brittle Fracture of a 420 SS Barrel Nut
M - Martensitic Stainless SteelP - Barrel NutAp - LiftingCd - Heat Treatment Defect
Cm - Kalling Etched Micrography by OMDf - Fracture
Micrography transverse to the fracture (top of the image) showing no relationship with the bands.
15
VIEW
ML00148 / Sep.2018
Brittle Fracture of a 420 SS Barrel Nut
M - Martensitic Stainless SteelP - Barrel NutAp - LiftingCd - Heat Treatment Defect
Cm - Kalling Etched Micrography by OMDf - Fracture
Micrographic detail of the fracture micromechanism showing no relationship with the bands and the intergranular morphology.
23
VIEW
ML00148 / Sep.2018
Brittle Fracture of a 420 SS Barrel Nut
M - Martensitic Stainless SteelP - Barrel NutAp - LiftingCd - Heat Treatment Defect
Cm - Kalling Etched Micrography by OMDf - Intergranular Fracture