Preferential Dissolution

4 cases · 37 images

Crevice Corrosion in a Subsea System — Aspect Before Analysis

Capture method: Optical Microscope clear all

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Uniform granular microstructure of the aluminum brass, monophasic alpha.
44
VIEW
ML00170 / Sep.2020
MIC in Aluminum Brass Tubes
M - Aluminum BrassP - Seamless tubeAp - MaritimeCd - Preferential Dissolution
Cm - FeCl3+HCl+Ethanol Etched MicroDf - Alpha
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
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
Macrography transverse to the circunferential weld, longitudinal to the piping, presenting the location, a little far from the welded joint margin, where the through wall cracking is positioned.
160
VIEW
ML00002 / Jan.2018
Preferential Dissolution and Cracks in SDSS
M - Super Duplex Stainless SteelP - Fabrication WeldAp - PipingCd - Preferential Dissolution
Cm - NaOH Electrolytic Etched MicroDf - Through Wall Cracking

More from these cases

ML00170 — MIC in Aluminum Brass TubesM - Aluminum BrassP - Seamless tubeAp - MaritimeCd - Preferential Dissolution
Micrographic detail of the granular structure of the aluminum brass, monophasic alpha.
44
VIEW
ML00170 / Sep.2020
MIC in Aluminum Brass Tubes
M - Aluminum BrassP - Seamless tubeAp - MaritimeCd - Preferential Dissolution
Cm - FeCl3+HCl+Ethanol Etched MicroDf - Alpha
Micrography of a transverse section of the tube, close to the leakage point. The thickness is localized reduced where the internal passive layer was ruptured, and the chemical effect of the biological proliferation created a high corrosion rate.
26
VIEW
ML00170 / Sep.2020
MIC in Aluminum Brass Tubes
M - Aluminum BrassP - Seamless tubeAp - MaritimeCd - Preferential Dissolution
Cm - FeCl3+HCl+Ethanol Etched MicroDf - Localized Thinning
Micrography of a transverse section of the tube at the localized reduced thickness point. Close to the internal surface.
28
VIEW
ML00170 / Sep.2020
MIC in Aluminum Brass Tubes
M - Aluminum BrassP - Seamless tubeAp - MaritimeCd - Preferential Dissolution
Cm - FeCl3+HCl+Ethanol Etched MicroDf - Internal Surface
Micrographic detail of a transverse section of the tube at the localized reduced thickness point. Close to the internal surface.
26
VIEW
ML00170 / Sep.2020
MIC in Aluminum Brass Tubes
M - Aluminum BrassP - Seamless tubeAp - MaritimeCd - Preferential Dissolution
Cm - FeCl3+HCl+Ethanol Etched MicroDf - Internal Surface
MIC in Aluminum Brass Tubes
2
VIEW
ML00170 / Sep.2020
MIC in Aluminum Brass Tubes
M - Aluminum BrassP - Seamless tubeAp - MaritimeCd - Preferential Dissolution
Cm - FeCl3+HCl+Ethanol Etched MicroDf - Localized Corrosion

+1 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.
65
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.
56
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 →

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 →

ML00002 — Preferential Dissolution and Cracks in SDSSM - Super Duplex Stainless SteelP - Fabrication WeldAp - PipingCd - Preferential Dissolution
Longitudinal section micrography at the cracked position, close to the external surface of the flange, showing cracks transverse to the thickness, associated to the microstructure.
147
VIEW
ML00002 / Jan.2018
Preferential Dissolution and Cracks in SDSS
M - Super Duplex Stainless SteelP - Fabrication WeldAp - PipingCd - Preferential Dissolution
Cm - NaOH Electrolytic Etched MicroDf - Cracks Transverse to the Surface
Longitudinal section micrography at the cracked position, close to the internal surface of the flange (exposed to the corrosive fluid), showing preferential dissolution associated to the microstructure.
133
VIEW
ML00002 / Jan.2018
Preferential Dissolution and Cracks in SDSS
M - Super Duplex Stainless SteelP - Fabrication WeldAp - PipingCd - Preferential Dissolution
Cm - NaOH Electrolytic Etched MicroDf - Preferential Dissolution
Micrography of the flange in the longitudinal section. The flange microstructure is ferritic austenitic, presenting a coarse structure.
102
VIEW
ML00002 / Jan.2018
Preferential Dissolution and Cracks in SDSS
M - Super Duplex Stainless SteelP - Fabrication WeldAp - PipingCd - Preferential Dissolution
Cm - NaOH Electrolytic Etched MicroDf - Coarse Structure
Micrographic detail of the flange microstructure in the longitudinal section. The flange is ferritic austenitic, presenting 70% of austenite. In the ferrite network there are evidences of precipitation/formation of detrimental phases.
113
VIEW
ML00002 / Jan.2018
Preferential Dissolution and Cracks in SDSS
M - Super Duplex Stainless SteelP - Fabrication WeldAp - PipingCd - Preferential Dissolution
Cm - NaOH Electrolytic Etched MicroDf - Duplex structure
Micrographic detail of the flange microstructure in the longitudinal section. The flange is ferritic austenitic, presenting 70% of austenite. In the ferrite network there are evidences of precipitation/formation of detrimental phases.
100
VIEW
ML00002 / Jan.2018
Preferential Dissolution and Cracks in SDSS
M - Super Duplex Stainless SteelP - Fabrication WeldAp - PipingCd - Preferential Dissolution
Cm - NaOH Electrolytic Etched MicroDf - Duplex structure