Hydrogen

3 cases · 3 images

Crevice Corrosion in a Subsea System — Aspect Before Analysis

Capture method: NItal Etched Macro clear all

Hydrogen — sub-branches

Hydride Formation 3Hydrogen Embrittlement 14

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Macrography of a stud longitudinal sectiion at the fracture position (top of the figure). It is possible to see a large secondary crack at the bottom of the thread fillet adjacent to the fracture surface, without any deformation evidence. This reveals a brittle material behavior, although the hardness measured at the stud end revealed 33HRc, as should be expected by the material specification.
56
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ML00136 / Jun.2018
Hydrogen Cracks of Subsea Studs
M - Low Alloy Medium Carbon QTP - FastenerAp - SubseaCd - Hydrogen Embrittlement
Cm - NItal Etched MacroDf - Secondary Cracks
Macrography of a longitudinal section of the stud, showing the flat fracture of brittle aspect.
46
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ML00127 / May.2018
Hydrogen Cracks of Cadmium Plated Studs
M - Low Alloy Medium Carbon QTP - Allen StudAp - Oil and GasCd - Hydrogen Embrittlement
Cm - NItal Etched MacroDf - Longitudinal Section
Macrography of the longitudinal section of the 2" diameter pin close to the fracture surface (top of the figure) in a section where the pin presented the final fracture (it is deformed). The lubrication hole is in the right side of the figure. It is possible to see several secondary cracks at the surface of the pin (left side of the figure), propagating only where there is a carburized layer. It is possible to see that the end of each secondary crack is blunted.
67
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ML00081 / Aug.2017
Hydrogen Cracking of a Chromium Plated Carburized Pin
M - Low Alloy for Thermochemical TreatmentP - Chromium PlatedAp - AutomotiveCd - Hydrogen Embrittlement
Cm - NItal Etched MacroDf - Carburized Layer