Optical Microscope

6 cases · 23 images

Crevice Corrosion in a Subsea System — Aspect Before Analysis

Product: Raw Material Microstructure: Ferritic Bainitic Detail focus: Damage clear all

Optical Microscope — sub-branches

Micro by OM, picric acid+FeCl3+H2O etch 1Nital Etched Micrography by OM 22

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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
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
Micrography of the welded joint fusion line presenting the liquation cracking. The weld metal is in the right side (bottom) and the forged connector heat affected zone is in the left side (top).
83
VIEW
ML00072 / Jan.2018
Liquation Cracks in a High Strength Joint
M - Low Alloy Medium Carbon QTP - Longitudinal Seam Welded PipeAp - O&G Well DrillingCd - Welding Defect
Cm - Nital Etched Micrography by OMDf - Cracking
The micrographic aspect of the cracks in a section transverse to the weld (the removed sample), shows that there are cracks with different sizes, the larger are filled with products that indicate they were opened for longer times.
67
VIEW
ML00071 / Jan.2019
Reheating Cracking of a CrMo Vessel Weld
M - CrMo SteelP - In Field WeldAp - EnergyCd - Welding Defect
Cm - Nital Etched Micrography by OMDf - Intergranular Cracking
Welded region etched to reveal impurities. The banded structure creates a continuous network parallel to the weld metal.
50
VIEW
ML00013 / Apr.2017
Welding Cracks in Mooring Chain
M - Low Alloy Low Carbon QTP - Welded PartAp - OffshoreCd - Welding Defect
Cm - Micro by OM, picric acid+FeCl3+H2O etchDf - Segregated Regions

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
ML00140 — Preferential Corrosion of Pipe Seam WeldM - Low Carbon SteelP - Longitudinal Seam Welded PipeAp - ShipCd - Preferential Dissolution
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
Micrography of the pipe in the leakage area, at the internal pipe surface, showing the preferential corrosion in the center of the autogenous weld and oxides inside the crevice. The morphology of the corrosion is similar to a cracking but the analysis show that it is a localized anodic process.
45
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 - Preferential Dissolution
Micrography of the pipe at the leakage position showing an oxide layer inside the crevice. The corrosion occurred exactly at the weld metal and the region at the margin of the damage shows the heat affected zone of the autogenous weld, with a refined grain size.
41
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 - Preferential Dissolution
Micrography of the internal pipe surface at the leakage position showing an oxide layer inside the crevice. The corrosion occurred exactly at the weld metal and the region at the margin of the damage shows the heat affected zone of the autogenous weld, with a refined grain size.
40
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 - Preferential Dissolution

+1 more from this case →

ML00072 — Liquation Cracks in a High Strength JointM - Low Alloy Medium Carbon QTP - Longitudinal Seam Welded PipeAp - O&G Well DrillingCd - Welding Defect
The HAZ presents microcracks at previous austenite grain boundaries. These regions melted during welding and generated cracks associated to low melting temperature phases.
48
VIEW
ML00072 / Jan.2018
Liquation Cracks in a High Strength Joint
M - Low Alloy Medium Carbon QTP - Longitudinal Seam Welded PipeAp - O&G Well DrillingCd - Welding Defect
Cm - Nital Etched Micrography by OMDf - Microcracks
The HAZ presents microcracks at previous austenite grain boundaries. These regions melted during welding and generated cracks associated to low melting temperature phases.
43
VIEW
ML00072 / Jan.2018
Liquation Cracks in a High Strength Joint
M - Low Alloy Medium Carbon QTP - Longitudinal Seam Welded PipeAp - O&G Well DrillingCd - Welding Defect
Cm - Nital Etched Micrography by OMDf - Microcracks
ML00071 — Reheating Cracking of a CrMo Vessel WeldM - CrMo SteelP - In Field WeldAp - EnergyCd - Welding Defect
Micrographic aspect of opened cracks, filled with oxides.
63
VIEW
ML00071 / Jan.2019
Reheating Cracking of a CrMo Vessel Weld
M - CrMo SteelP - In Field WeldAp - EnergyCd - Welding Defect
Cm - Nital Etched Micrography by OMDf - Cracks
Micrographic details of opened cracks, filled with oxides.
56
VIEW
ML00071 / Jan.2019
Reheating Cracking of a CrMo Vessel Weld
M - CrMo SteelP - In Field WeldAp - EnergyCd - Welding Defect
Cm - Nital Etched Micrography by OMDf - Cracks
Micrographic aspect of thin cracks.
59
VIEW
ML00071 / Jan.2019
Reheating Cracking of a CrMo Vessel Weld
M - CrMo SteelP - In Field WeldAp - EnergyCd - Welding Defect
Cm - Nital Etched Micrography by OMDf - Cracks
Micrographic details of thin cracks.
63
VIEW
ML00071 / Jan.2019
Reheating Cracking of a CrMo Vessel Weld
M - CrMo SteelP - In Field WeldAp - EnergyCd - Welding Defect
Cm - Nital Etched Micrography by OMDf - Cracks
ML00013 — Welding Cracks in Mooring ChainM - Low Alloy Low Carbon QTP - Welded PartAp - OffshoreCd - Welding Defect
Micrography of a longitudinal section of the mooring chain, at the main crack position. The crack follows a network of segregations.
48
VIEW
ML00013 / Apr.2017
Welding Cracks in Mooring Chain
M - Low Alloy Low Carbon QTP - Welded PartAp - OffshoreCd - Welding Defect
Cm - Nital Etched Micrography by OMDf - Segregated Regions