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3 cases · 18 images

Crevice Corrosion in a Subsea System — Aspect Before Analysis

Microstructure: Duplex Ferritic Austenitic Capture method: Scanning Electron Microscope clear all

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Microstructural analysis of the valve body structure, close to the position where the cracking has occurred. The structure is ferritic austenitic, with a large amount of detrimental phases associated to the ferritic structure, probably sigma phase.
92
VIEW
ML00134 / Aug.2020
Brittle Fracture of a Superduplex Valve Body
M - Super Duplex Stainless SteelP - Fabrication WeldAp - SubseaCd - Brittle Fracture
Cm - Micrography by SEMDf - Sigma
Fractographic detail of the longitudinal Charpy V testpiece, broken at -46°C and presenting energy of 64J (the average energy of three tespieces was 70J). The Charpy V testpiece was removed from the center of the bar. The micromechanism is quasicleavage and the test in this direction presented energy values superior than the minimum requirement of 45J.
944
VIEW
ML00123 / Feb.2018
Non Qualified Superduplex for Subsea
M - Super Duplex Stainless SteelP - BarAp - Oil and GasCd - Not according to spec
Cm - Fractography by SEMDf - Broken Testpiece
External surface aspect of the flange showing preferential dissolution, responsible for nucleation of the through wall cracking.
245
VIEW
ML00002 / Jan.2018
Preferential Dissolution and Cracks in SDSS
M - Super Duplex Stainless SteelP - Fabrication WeldAp - PipingCd - Preferential Dissolution
Cm - Surface Aspect by SEMDf - Preferential Dissolution

More from these cases

ML00134 — Brittle Fracture of a Superduplex Valve BodyM - Super Duplex Stainless SteelP - Fabrication WeldAp - SubseaCd - Brittle Fracture
Micrographic details by scaning electron microscopy. The structure is ferritic austenitic, with a large amount of detrimental phases associated to the ferritic structure, probably sigma phase.
85
VIEW
ML00134 / Aug.2020
Brittle Fracture of a Superduplex Valve Body
M - Super Duplex Stainless SteelP - Fabrication WeldAp - SubseaCd - Brittle Fracture
Cm - Micrography by SEMDf - Sigma
High magnification details by scaning electron microscopy. The structure is ferritic austenitic, with a large amount of detrimental phases associated to the ferritic structure, probably sigma phase.
81
VIEW
ML00134 / Aug.2020
Brittle Fracture of a Superduplex Valve Body
M - Super Duplex Stainless SteelP - Fabrication WeldAp - SubseaCd - Brittle Fracture
Cm - Micrography by SEMDf - Sigma
Higher magnification detail of the sigma phase by scaning electron microscopy.
76
VIEW
ML00134 / Aug.2020
Brittle Fracture of a Superduplex Valve Body
M - Super Duplex Stainless SteelP - Fabrication WeldAp - SubseaCd - Brittle Fracture
Cm - Micrography by SEMDf - Sigma
Fractographic aspect of the valve body fracture surface after opening the crack. The fracture micromechanism is brittle, by cleavage, with several secondary microcracks associated to the sigma phase.
54
VIEW
ML00134 / Aug.2020
Brittle Fracture of a Superduplex Valve Body
M - Super Duplex Stainless SteelP - Fabrication WeldAp - SubseaCd - Brittle Fracture
Cm - Fractography by SEMDf - Cleavage Facets
Fractographic detail of the valve body fracture surface after opening the crack. The fracture micromechanism is brittle, by cleavage, with several secondary microcracks associated to the sigma phase.
52
VIEW
ML00134 / Aug.2020
Brittle Fracture of a Superduplex Valve Body
M - Super Duplex Stainless SteelP - Fabrication WeldAp - SubseaCd - Brittle Fracture
Cm - Fractography by SEMDf - Cleavage Facets

+1 more from this case →

ML00123 — Non Qualified Superduplex for SubseaM - Super Duplex Stainless SteelP - BarAp - Oil and GasCd - Not according to spec
Fractography of the broken Charpy V testpiece, longitudinal, broken at -46°C and presenting energy of 64J (the average of three values was 70J). In this direction the material presented an energy value higher than the minimum requirement of 45J.
109
VIEW
ML00123 / Feb.2018
Non Qualified Superduplex for Subsea
M - Super Duplex Stainless SteelP - BarAp - Oil and GasCd - Not according to spec
Cm - Fractography by SEMDf - Broken Testpiece
Fractography of the Charpy V testpiece, transverse section, broken at -46°C and presenting energy of 20J (the average of three results was 33J). The coarse structure and the alignement created a condition for low energy results in this specific direction, and the material did not present the minimum requirement of 45J.
103
VIEW
ML00123 / Feb.2018
Non Qualified Superduplex for Subsea
M - Super Duplex Stainless SteelP - BarAp - Oil and GasCd - Not according to spec
Cm - Fractography by SEMDf - Broken Testpiece
ML00002 — Preferential Dissolution and Cracks in SDSSM - Super Duplex Stainless SteelP - Fabrication WeldAp - PipingCd - Preferential Dissolution
Detail of the region at the flange external surface where the material is suffering the preferential corrosion.
177
VIEW
ML00002 / Jan.2018
Preferential Dissolution and Cracks in SDSS
M - Super Duplex Stainless SteelP - Fabrication WeldAp - PipingCd - Preferential Dissolution
Cm - Surface Aspect by SEMDf - Preferential Dissolution
Micrographic detail of the through wall cracking in the middle of the thickness, showing that the cracking is associated to ferrite network in the (super)duplex microstructure.
128
VIEW
ML00002 / Jan.2018
Preferential Dissolution and Cracks in SDSS
M - Super Duplex Stainless SteelP - Fabrication WeldAp - PipingCd - Preferential Dissolution
Cm - Micrography by SEMDf - Crack
Micrographic detail of the cracking, associated to the ferrite network, that presents both corrosion (preferential dissolution) and fracture (clevage) aspects.
128
VIEW
ML00002 / Jan.2018
Preferential Dissolution and Cracks in SDSS
M - Super Duplex Stainless SteelP - Fabrication WeldAp - PipingCd - Preferential Dissolution
Cm - Electrolytic Etch Micrography by SEMDf - Crack
The fracture surface, although presenting a large amount of corrosion products, shows also evidences of a brittle behavior with regions of cleavage micromechanism.
116
VIEW
ML00002 / Jan.2018
Preferential Dissolution and Cracks in SDSS
M - Super Duplex Stainless SteelP - Fabrication WeldAp - PipingCd - Preferential Dissolution
Cm - Fractography by SEMDf - Cleavage Facets
Micrographic detail of the ferrite network with evidences of precipitation/formation of detrimental phases. NaOH solution was adopted for the electrolytic etching.
86
VIEW
ML00002 / Jan.2018
Preferential Dissolution and Cracks in SDSS
M - Super Duplex Stainless SteelP - Fabrication WeldAp - PipingCd - Preferential Dissolution
Cm - Electrolytic Etch Micrography by SEMDf - Delta ferrite

+2 more from this case →