Sampling and Analysis

2 cases · 23 images

Crevice Corrosion in a Subsea System — Aspect Before Analysis

Microstructure: Ferrite and Carbides clear all

Sampling and Analysis — sub-branches

Base Metal 3Close to the External Surface 3Close to the Internal Surface 3Heat Affected Zone 6Internal Surface 1Weld Metal 6Welded Joint 1

Results

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Identification of the regions of metallographies of the base metal, heat affected zone (HAZ) and weld metal. Locations in the root, in the center of the thickness and close to the tube OD (external surface).
118
VIEW
ML00177 / Dec.2021
Cr-Mo Seam Welded Tube
M - CrMo SteelP - Longitudinally Seam WeldedAp - Fired HeaterCd - Not according to spec
Cm - NItal Etched MacroDf - Welded Joint
Aspect of the internal diameter surface presenting several cracks in the axial direction, caused by the contact with the shaft. The roller bearing presented a too low hardness level (21 HRc average) in this ID position.
90
VIEW
ML00131 / Apr.2018
Brittle Failure of a Soft Roller Bearing
M - Wear Resistant SteelP - Roller BearingAp - Mechanical IndustryCd - Heat Treatment Defect
Cm - Aspect Before AnalysisDf - Internal Surface

More from these cases

ML00177 — Cr-Mo Seam Welded TubeM - CrMo SteelP - Longitudinally Seam WeldedAp - Fired HeaterCd - Not according to spec
BASE METAL SURFACE - Ferritic structure, grain refined.
90
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 - Base Metal
HAZ SURFACE
72
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 - Last Bead HAZ
HAZ SURFACE
66
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 - Last Bead HAZ
WELD METAL SURFACE
47
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 - Weld Metal in the Cap
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 - Weld Metal in the Cap

+10 more from this case →

ML00131 — Brittle Failure of a Soft Roller BearingM - Wear Resistant SteelP - Roller BearingAp - Mechanical IndustryCd - Heat Treatment Defect
Micrography of an axial section of the roller bearing, at the external surface, where the hardness level was about 64 HRc (higher than the limit of 58HRc to 62 HRc).
86
VIEW
ML00131 / Apr.2018
Brittle Failure of a Soft Roller Bearing
M - Wear Resistant SteelP - Roller BearingAp - Mechanical IndustryCd - Heat Treatment Defect
Cm - Nital Etched Micrography by OMDf - Close to the External Surface
Fractography of the roller bearing, close to the external surface. In this position the fracture of the cylindrical roller bearing shows micromechanisms of decohesion at large carbides (cracked) and quasecleavage, typical of overloading this high strength tool steel (martensitic with carbides at 64 HRc).
75
VIEW
ML00131 / Apr.2018
Brittle Failure of a Soft Roller Bearing
M - Wear Resistant SteelP - Roller BearingAp - Mechanical IndustryCd - Heat Treatment Defect
Cm - Fractography by SEMDf - Close to the External Surface
Micrography of an axial section of the roller bearing, at the internal surface, where the hardness level was about 21 HRc, indicating that in this region the material was not properly quenched and tempered.
75
VIEW
ML00131 / Apr.2018
Brittle Failure of a Soft Roller Bearing
M - Wear Resistant SteelP - Roller BearingAp - Mechanical IndustryCd - Heat Treatment Defect
Cm - Nital Etched Micrography by OMDf - Close to the Internal Surface
Aspect of the roller bearing fracture surface, by scanning electron microscopy, close to the internal surface. In this position the fracture shows ductile micromechanisms (dimples) as well as decohesion of large carbides and (brittle) cleavage facets, typical of overloading this low strenght, and low toughness, ferritic structure (21 HRc). The structure in this region, ferritic with large broken carbides and small rounded carbides, is of a low toughness, as indicated by the fracture.
54
VIEW
ML00131 / Apr.2018
Brittle Failure of a Soft Roller Bearing
M - Wear Resistant SteelP - Roller BearingAp - Mechanical IndustryCd - Heat Treatment Defect
Cm - Fractography by SEMDf - Close to the Internal Surface
Fracture micromechanism at a region close to the internal surface. In this position the fracture shows ductile micromechanisms (dimples) as well as decohesion of large carbides and (brittle) cleavage facets, typical of overloading this low strenght ferritic structure (21 HRc). The structure in this region, ferritic with large broken carbides and small rounded carbides, is of a low toughness, as indicated by the fracture.
44
VIEW
ML00131 / Apr.2018
Brittle Failure of a Soft Roller Bearing
M - Wear Resistant SteelP - Roller BearingAp - Mechanical IndustryCd - Heat Treatment Defect
Cm - Fractography by SEMDf - Close to the Internal Surface

+1 more from this case →