Optical Microscope

2 cases · 38 images

Crevice Corrosion in a Subsea System — Aspect Before Analysis

Product: Valve Body clear all

Optical Microscope — sub-branches

As polished micrography 8NaOH Electrolytic Etched Micro 14Nital Etched Micrography by OM 16

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Low magnification micrography of a longitudinal section of the valve body, in the center of the thickness. As expected for this high strength steel, the microstructure is martensitic, but with segregation bands.
48
VIEW
ML00162 / Apr.2020
Valve Body Crack Growth from Weld Defects
M - Low Alloy Medium Carbon QTP - Valve BodyAp - O&G Well DrillingCd - Fatigue Induced by a Defect
Cm - Nital Etched Micrography by OMDf - Banded Structure
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.
106
VIEW
ML00134 / Aug.2020
Brittle Fracture of a Superduplex Valve Body
M - Super Duplex Stainless SteelP - Fabrication WeldAp - SubseaCd - Brittle Fracture
Cm - NaOH Electrolytic Etched MicroDf - Sigma

More from these cases

ML00162 — Valve Body Crack Growth from Weld DefectsM - Low Alloy Medium Carbon QTP - Valve BodyAp - O&G Well DrillingCd - Fatigue Induced by a Defect
Micrography of a longitudinal section of the valve body presenting a martensitic microstructure. The structure is banded and the darker regions show inclusions (grey sulfides).
50
VIEW
ML00162 / Apr.2020
Valve Body Crack Growth from Weld Defects
M - Low Alloy Medium Carbon QTP - Valve BodyAp - O&G Well DrillingCd - Fatigue Induced by a Defect
Cm - Nital Etched Micrography by OMDf - Martensite
Micrographic detail of the martensitic microstructure, in the longitudinal section. The hardness of the valve body is 34 HRc (Rockwell C) all through the thickness.
47
VIEW
ML00162 / Apr.2020
Valve Body Crack Growth from Weld Defects
M - Low Alloy Medium Carbon QTP - Valve BodyAp - O&G Well DrillingCd - Fatigue Induced by a Defect
Cm - Nital Etched Micrography by OMDf - Martensite
Macrography of the longitudinal section of the valve body, at the cracked position, a little far from the actuator hole. The valve body is 40 mm thick at this position and it is possible to see that at this position only one region is welded in repair, close to the outer surface (top), and there is a crack, transverse to the thickness, that is difficult to see with this magnification and that is clearly the propagation in fatigue.
47
VIEW
ML00162 / Apr.2020
Valve Body Crack Growth from Weld Defects
M - Low Alloy Medium Carbon QTP - Valve BodyAp - O&G Well DrillingCd - Fatigue Induced by a Defect
Cm - Nital Etched Micrography by OMDf - Fatigue Crack
Low magnification micrography at the weld repair close to the internal surface of the valve body, in a longitudinal section. Weld metal to the bottom and heat affected zone to the top.
42
VIEW
ML00162 / Apr.2020
Valve Body Crack Growth from Weld Defects
M - Low Alloy Medium Carbon QTP - Valve BodyAp - O&G Well DrillingCd - Fatigue Induced by a Defect
Cm - Nital Etched Micrography by OMDf - Weld Repair
Micrography of the weld repair at the fusion line. Weld metal to the right and heat affected zone to the left.
37
VIEW
ML00162 / Apr.2020
Valve Body Crack Growth from Weld Defects
M - Low Alloy Medium Carbon QTP - Valve BodyAp - O&G Well DrillingCd - Fatigue Induced by a Defect
Cm - Nital Etched Micrography by OMDf - Fusion Line

+18 more from this case →

ML00134 — Brittle Fracture of a Superduplex Valve BodyM - Super Duplex Stainless SteelP - Fabrication WeldAp - SubseaCd - Brittle Fracture
Micrographic detail 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.
102
VIEW
ML00134 / Aug.2020
Brittle Fracture of a Superduplex Valve Body
M - Super Duplex Stainless SteelP - Fabrication WeldAp - SubseaCd - Brittle Fracture
Cm - NaOH Electrolytic Etched MicroDf - Sigma
Metallographic detail of the large amount of sigma phase, associated to the ferritic structure.
105
VIEW
ML00134 / Aug.2020
Brittle Fracture of a Superduplex Valve Body
M - Super Duplex Stainless SteelP - Fabrication WeldAp - SubseaCd - Brittle Fracture
Cm - NaOH Electrolytic Etched MicroDf - Sigma
Microstructural analysis of the valve body structure, far from the position where the cracking has occurred, in the bottom of the body. The structure is ferritic austenitic, with some sigma phase, not in a large amount, indicating the valve structure was not uniform.
67
VIEW
ML00134 / Aug.2020
Brittle Fracture of a Superduplex Valve Body
M - Super Duplex Stainless SteelP - Fabrication WeldAp - SubseaCd - Brittle Fracture
Cm - NaOH Electrolytic Etched MicroDf - Ferrite and Austenite
Micrographic detail of the valve body structure, far from the position where the cracking has occurred, in the bottom of the body. The structure is ferritic austenitic, with some sigma phase, not in a large amount, indicating the valve structure was not uniform.
63
VIEW
ML00134 / Aug.2020
Brittle Fracture of a Superduplex Valve Body
M - Super Duplex Stainless SteelP - Fabrication WeldAp - SubseaCd - Brittle Fracture
Cm - NaOH Electrolytic Etched MicroDf - Ferrite and Austenite
Micrographic detail of the valve body structure, far from the position where the cracking has occurred, in the bottom of the body. The structure is ferritic austenitic, with some sigma phase, not in a large amount, indicating the valve structure was not uniform.
61
VIEW
ML00134 / Aug.2020
Brittle Fracture of a Superduplex Valve Body
M - Super Duplex Stainless SteelP - Fabrication WeldAp - SubseaCd - Brittle Fracture
Cm - NaOH Electrolytic Etched MicroDf - Ferrite and Austenite

+8 more from this case →