ASTM

2 cases · 47 images

Crevice Corrosion in a Subsea System — Aspect Before Analysis

Microstructure: Segregation Bands Capture method: Optical Microscope clear all

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BASE METAL SURFACE - Ferritic structure, grain refined.
90
VIEW
ML00177 / Dec.2021
Cr-Mo Seam Welded Tube
M - CrMo SteelP - Longitudinally Seam WeldedAp - Fired HeaterCd - Not according to spec
Cm - Nital Etched Micrography by OMDf - Base Metal
Longitudinal section micrography in a position of the thread, far from the failure. The stud presented a quenching and tempering structure and the thread was machined.
84
VIEW
ML00136 / Jun.2018
Hydrogen Cracks of Subsea Studs
M - Low Alloy Medium Carbon QTP - FastenerAp - SubseaCd - Hydrogen Embrittlement
Cm - Nital Etched Micrography by OMDf - Machined Thread

More from these cases

ML00177 — Cr-Mo Seam Welded TubeM - CrMo SteelP - Longitudinally Seam WeldedAp - Fired HeaterCd - Not according to spec
BASE METAL SURFACE - The micrography (transverse to the tube) presents the ferritic/pearlitic/bainitic structure.
75
VIEW
ML00177 / Dec.2021
Cr-Mo Seam Welded Tube
M - CrMo SteelP - Longitudinally Seam WeldedAp - Fired HeaterCd - Not according to spec
Cm - Nital Etched Micrography by OMDf - Granular structure
BASE METAL SURFACE - The microstructure of the base metal is ferritic/pearlitic/bainitic.
74
VIEW
ML00177 / Dec.2021
Cr-Mo Seam Welded Tube
M - CrMo SteelP - Longitudinally Seam WeldedAp - Fired HeaterCd - Not according to spec
Cm - Nital Etched Micrography by OMDf - Grain refined structure
HAZ SURFACE
72
VIEW
ML00177 / Dec.2021
Cr-Mo Seam Welded Tube
M - CrMo SteelP - Longitudinally Seam WeldedAp - Fired HeaterCd - Not according to spec
Cm - Nital Etched Micrography by OMDf - Last Bead HAZ
HAZ SURFACE
66
VIEW
ML00177 / Dec.2021
Cr-Mo Seam Welded Tube
M - CrMo SteelP - Longitudinally Seam WeldedAp - Fired HeaterCd - Not according to spec
Cm - Nital Etched Micrography by OMDf - Last Bead HAZ
HAZ SURFACE
55
VIEW
ML00177 / Dec.2021
Cr-Mo Seam Welded Tube
M - CrMo SteelP - Longitudinally Seam WeldedAp - Fired HeaterCd - Not according to spec
Cm - Nital Etched Micrography by OMDf - Bainitic HAZ

+18 more from this case →

ML00136 — Hydrogen Cracks of Subsea StudsM - Low Alloy Medium Carbon QTP - FastenerAp - SubseaCd - Hydrogen Embrittlement
Microstructure of the stud in the longitudinal section, presenting segregated bands, not uniformly distributed in the section. The bands are associated to elongated and aligned inclusions, and a refined microstructure, probably due to carbon and alloying elements concentration.
69
VIEW
ML00136 / Jun.2018
Hydrogen Cracks of Subsea Studs
M - Low Alloy Medium Carbon QTP - FastenerAp - SubseaCd - Hydrogen Embrittlement
Cm - Nital Etched Micrography by OMDf - Banded Structure
Microstructure of the stud in the longitudinal section, out of a region of segregation, where the tempered martensitic microstructure appears more uniform.
72
VIEW
ML00136 / Jun.2018
Hydrogen Cracks of Subsea Studs
M - Low Alloy Medium Carbon QTP - FastenerAp - SubseaCd - Hydrogen Embrittlement
Cm - Nital Etched Micrography by OMDf - Martensite
Micrographic detail of the segregated bands, not uniformly distributed in the section. The bands are associated to elongated and aligned inclusions, and a refined microstructure, probably due to carbon and alloying elements concentration. The localized microhardness (50g) in the band showed levels about 540HV, and out of the band, in the same localtion, presented an average hardness of 321 HV, indicating that the material is non uniform in the regions where there are bands.
66
VIEW
ML00136 / Jun.2018
Hydrogen Cracks of Subsea Studs
M - Low Alloy Medium Carbon QTP - FastenerAp - SubseaCd - Hydrogen Embrittlement
Cm - Nital Etched Micrography by OMDf - Banded Structure
Micrographic detail of the martensitic structure of the stud in the longitudinal section, out of a region of segregation, where the microstructure appears more uniform and the microhardness is about 370HV (50g).
62
VIEW
ML00136 / Jun.2018
Hydrogen Cracks of Subsea Studs
M - Low Alloy Medium Carbon QTP - FastenerAp - SubseaCd - Hydrogen Embrittlement
Cm - Nital Etched Micrography by OMDf - Martensite
Low magnification micrography of a stud longitudinal section in the first thread fillet adjacent to the fracture, presenting a large secondary crack 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.
47
VIEW
ML00136 / Jun.2018
Hydrogen Cracks of Subsea Studs
M - Low Alloy Medium Carbon QTP - FastenerAp - SubseaCd - Hydrogen Embrittlement
Cm - Nital Etched Micrography by OMDf - Secondary Cracks

+17 more from this case →