Subsea

1 case · 4 images

Crevice Corrosion in a Subsea System — Aspect Before Analysis

Condition: Brittle Behavior Detail focus: Heat Affected Zone clear all

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Micrography of the valve at the welded joint of the body to the insert (fillet weld). The cracking was arrested at the position of this welded joint because the structures of the weld metal, insert and heat affected zones are tough (austenitic in the weld metal and insert, and free from sigma in the HAZ) .
46
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 - Heat Affected Zone

More from these cases

ML00134 — Brittle Fracture of a Superduplex Valve BodyM - Super Duplex Stainless SteelP - Fabrication WeldAp - SubseaCd - Brittle Fracture
Micrographic detail of the fusion line of the welded joint of the body to the insert (fillet weld). The cracking was arrested at the position of this welded joint because the structures of the weld metal, insert and heat affected zones are tough (austenitic in the weld metal and insert, and free from sigma in the HAZ) .
39
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 - Heat Affected Zone
Micrography of the valve at the welded joint of the body to the insert (fillet weld). The heat affected zone shows that the sigma phase was removed, which means that the base metal was degradated and during welding the thermal cycle created a condition to remove the sigma phase (dissolve it).
38
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 - Heat Affected Zone
Micrographic detail of the heat affected zone of the valve to the insert joint showing that the sigma phase was removed, which means that the base metal was degradated and during welding the thermal cycle created a condition to dissolve the sigma phase.
39
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 - Heat Affected Zone