Optical Microscope

3 cases · 38 images

Crevice Corrosion in a Subsea System — Aspect Before Analysis

Product: Fastener Standard: A clear all

Optical Microscope — sub-branches

As polished micrography 9Micrography by OM 3Nital Etched Micrography by OM 26

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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
Micrographic aspect of the rolled thread that was heat treated later. Longitudinal section.
134
VIEW
ML00130 / Jun.2018
Fatigue Fracture of Overloaded Bolts
M - Low Alloy Medium Carbon QTP - FastenerAp - O&G Well DrillingCd - Mechanical Fatigue
Cm - Nital Etched Micrography by OMDf - At the Surface
Micrography of a longitudinal section of the bolt at the fracture surface. The material showed several creep voids and interconnected cracks. The broken bolt remained in service during some time and the fracture surface presented a thick oxide layer(grey). As polished.
529
VIEW
ML00004 / Jun.2018
Creep in High Temperature Bolts
M - CrMo SteelP - FastenerAp - Gas TurbineCd - Creep
Cm - Micrography by OMDf - Oxide Layer

More from these cases

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 →

ML00130 — Fatigue Fracture of Overloaded BoltsM - Low Alloy Medium Carbon QTP - FastenerAp - O&G Well DrillingCd - Mechanical Fatigue
Micrographic aspect of the rolled thread that was heat treated later. Longitudinal section. The bolt was quenched and tempered to 30HRc and presented a martensitic structure.
124
VIEW
ML00130 / Jun.2018
Fatigue Fracture of Overloaded Bolts
M - Low Alloy Medium Carbon QTP - FastenerAp - O&G Well DrillingCd - Mechanical Fatigue
Cm - Nital Etched Micrography by OMDf - At the Surface
Micrographic detail of the rolled thread that was heat treated later. The bolt was quenched and tempered to 30 HRc and presented a martensitic structure.
111
VIEW
ML00130 / Jun.2018
Fatigue Fracture of Overloaded Bolts
M - Low Alloy Medium Carbon QTP - FastenerAp - O&G Well DrillingCd - Mechanical Fatigue
Cm - Nital Etched Micrography by OMDf - Martensite
The microstructure of the bolt is martensitic in the center of the thickness. Longitudinal section.
110
VIEW
ML00130 / Jun.2018
Fatigue Fracture of Overloaded Bolts
M - Low Alloy Medium Carbon QTP - FastenerAp - O&G Well DrillingCd - Mechanical Fatigue
Cm - Nital Etched Micrography by OMDf - In the Center of the Thickness
The microstructure of the bolt is martensitic in the center of the thickness. Longitudinal section.
103
VIEW
ML00130 / Jun.2018
Fatigue Fracture of Overloaded Bolts
M - Low Alloy Medium Carbon QTP - FastenerAp - O&G Well DrillingCd - Mechanical Fatigue
Cm - Nital Etched Micrography by OMDf - Martensite
Micrographic aspect of the rolled thread that was heat treated later. Longitudinal section.
115
VIEW
ML00130 / Jun.2018
Fatigue Fracture of Overloaded Bolts
M - Low Alloy Medium Carbon QTP - FastenerAp - O&G Well DrillingCd - Mechanical Fatigue
Cm - Nital Etched Micrography by OMDf - At the Surface

+3 more from this case →

ML00004 — Creep in High Temperature BoltsM - CrMo SteelP - FastenerAp - Gas TurbineCd - Creep
Micrographic detail of the creep voids and interconnected cracks. The broken bolt remained in service during some time and the fracture surface presented a thick oxide layer(grey). As polished.
121
VIEW
ML00004 / Jun.2018
Creep in High Temperature Bolts
M - CrMo SteelP - FastenerAp - Gas TurbineCd - Creep
Cm - Micrography by OMDf - Interconnected Cracks
Micrographic detail of the creep voids and interconnected cracks. The broken bolt remained in service during some time and the fracture surface presented a thick oxide layer(grey). As polished.
101
VIEW
ML00004 / Jun.2018
Creep in High Temperature Bolts
M - CrMo SteelP - FastenerAp - Gas TurbineCd - Creep
Cm - Micrography by OMDf - Voids
Micrography of a longitudinal section of a CrMov steel bolt that broke in service by a creep mechanism in a gas turbine. Tempered structure. Interconnected cracks paralled to the fracture surface.
95
VIEW
ML00004 / Jun.2018
Creep in High Temperature Bolts
M - CrMo SteelP - FastenerAp - Gas TurbineCd - Creep
Cm - Nital Etched Micrography by OMDf - Crack
Micrographic detail of a longitudinal section of the bolt far from the fracture, presenting a tempered structure.
82
VIEW
ML00004 / Jun.2018
Creep in High Temperature Bolts
M - CrMo SteelP - FastenerAp - Gas TurbineCd - Creep
Cm - Nital Etched Micrography by OMDf - Tempered Structure
Micrographic detail of a longitudinal section of the bolt close to the fracture, presenting an overtempered structure.
76
VIEW
ML00004 / Jun.2018
Creep in High Temperature Bolts
M - CrMo SteelP - FastenerAp - Gas TurbineCd - Creep
Cm - Nital Etched Micrography by OMDf - Overtempered Structure