Sigma

1 case · 4 images

Crevice Corrosion in a Subsea System — Aspect Before Analysis

Microstructure: Surface layer of Thermal Spray clear all

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Micrographic detail of the interface between the substrate and the first thermal spray layer. The substrate (bottom of the figure) shows a ferritic-austenitic microstructure and detrimental phases that look like sigma at the delta and gamma interface. The thermal spray layer (top of the figure) presents the non-etched stainless steel, disposed in layers, with oxides (gray) and voids (black). The substrate is deformed in a thin layer at the interface.
34
VIEW
ML00147 / Aug.2018
WC Layer Detached from a Cast Lean Duplex
M - Lean Duplex Stainless SteelP - Centrifugal CastingAp - ShipCd - Lack of Sealing
Cm - NaOH Electrolytic Etched MicroDf - Sigma

More from these cases

ML00147 — WC Layer Detached from a Cast Lean DuplexM - Lean Duplex Stainless SteelP - Centrifugal CastingAp - ShipCd - Lack of Sealing
Micrographic detail of the longitudinal section of the cast sleeve in the middle of the thickness. The microstructure is duplex, austenitic and ferritic. The etch presents different colours for the phases. The yellow is associated to detrimental phases, like sigma, at the ferritic phase (ligh blue) and the white phase is the austenite.
30
VIEW
ML00147 / Aug.2018
WC Layer Detached from a Cast Lean Duplex
M - Lean Duplex Stainless SteelP - Centrifugal CastingAp - ShipCd - Lack of Sealing
Cm - NaOH Electrolytic Etched MicroDf - Sigma
Micrographic detail, by scanning electron microscopy, of the duplex, austenitic and ferritic, structure with sigma phase.
16
VIEW
ML00147 / Aug.2018
WC Layer Detached from a Cast Lean Duplex
M - Lean Duplex Stainless SteelP - Centrifugal CastingAp - ShipCd - Lack of Sealing
Cm - Electrolytic Etch Micrography by SEMDf - Sigma
Micrographic detail of the longitudinal section of the cast sleeve at the ID. The microstructure is duplex, austenitic and ferritic. The etch presents different colours for the phases. The yellow is associated to detrimental phases, like sigma, at the ferritic phase (ligh blue) and the white phase is the austenite. No evidences of corrosion. The environment in this position is non corrosive, oil.
19
VIEW
ML00147 / Aug.2018
WC Layer Detached from a Cast Lean Duplex
M - Lean Duplex Stainless SteelP - Centrifugal CastingAp - ShipCd - Lack of Sealing
Cm - NaOH Electrolytic Etched MicroDf - Sigma