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Crevice Corrosion in a Subsea System — Aspect Before Analysis

Product: Bolt Standard: ASTM clear all

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Optical micrography of a longitudinal section of the fractured bolt, at the thread. The material is austenitic, free from carbides, and the threads were almost removed by the stress corrosion cracks.
756
VIEW
ML00157 / Feb.2020
Bolts Under Chloride SCC Conditions
M - Austenitic Stainless SteelP - BoltAp - Oil and GasCd - Stress Corrosion
Cm - Oxalic Acid Electrolytic EtchDf - Stress Corrosion Cracks
Aspect of the bolt fracture surface by scanning electron microscopy, (SEM) presenting striations that indicate a FATIGUE micromechanism. The bolt is of a medium strength (class 8.8) low alloy steel, medium carbon, quenched and tempered.
1123
VIEW
ML00130 / Jun.2018
Fatigue Fracture of Overloaded Bolts
M - Low Alloy Medium Carbon QTP - FastenerAp - O&G Well DrillingCd - Mechanical Fatigue
Cm - Fractography by SEMDf - Fatigue Fracture
Micrographic detail of a longitudinal section in the center of the bolt. Granular austenitic microstructure, equiaxial, primary precipitates (isolated), precipitation hardened (not detectable by metalography, only because of the hardness level)
431
VIEW
ML00106 / Dec.2017
Inconel 718 Submarine Bolt
M - NiCrFe AlloyP - BoltAp - SubseaCd - Typical manufacturing
Cm - Kalling Etched Micrography by OMDf - Austenite
Aspect of the bolt with a special head, to be adopted in subsea condition. M12, 1/2" 13UNC.
342
VIEW
ML00105 / Jun.2018
Inconel 718 Bolt of Special Head
M - NiCrFe AlloyP - FastenerAp - SubseaCd - Typical manufacturing
Cm - Aspect Before AnalysisDf - General View
Micrographic detail of the strain hardened austenitic structure in the longitudinal section of the bolt.
441
VIEW
ML00101 / Nov.2017
High Strength 316SS Bolt
M - Austenitic Stainless SteelP - BoltAp - SubseaCd - Typical manufacturing
Cm - Micrography by OM using A262 Method ADf - Austenite
Micrographic detail of the strain hardened austenitic structure in the longitudinal section of the bolt.
412
VIEW
ML00087 / Nov.2017
High Strength Austenitic SS Bolt
M - Austenitic Stainless SteelP - BoltAp - SubseaCd - Typical manufacturing
Cm - Micrography by OM using A262 Method ADf - Austenite
Micrographic detail of the austenitic structure at the surface, where the grain size of the material increased. By optical microscopy the intragranular precipitation due to solution annealing and aging is not revealed.
794
VIEW
ML00089 / Sep.2017
Inconel 718 Allen Bolt for Subsea Application
M - NiCrFe AlloyP - Machined PartAp - SubseaCd - Typical manufacturing
Cm - Kalling Etched Micrography by OMDf - Austenite
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

ML00157 — Bolts Under Chloride SCC ConditionsM - Austenitic Stainless SteelP - BoltAp - Oil and GasCd - Stress Corrosion
Aspect of a 5/16" bolt manufactured in an AISI 316 austenitic stainless steel, that was also operating inside the pressure vessel, but was not yet damaged. It is a hexagonal head bolt, 1 1/2" long, fastened with a hexagonal nut and a lock washer.
118
VIEW
ML00157 / Feb.2020
Bolts Under Chloride SCC Conditions
M - Austenitic Stainless SteelP - BoltAp - Oil and GasCd - Stress Corrosion
Cm - Aspect Before AnalysisDf - General View
Low magnification micrography, by optical microscope, of the longitudinal section of a damaged bolt, in the center of the thickness. The microstructure is austenitic, free from carbides.
100
VIEW
ML00157 / Feb.2020
Bolts Under Chloride SCC Conditions
M - Austenitic Stainless SteelP - BoltAp - Oil and GasCd - Stress Corrosion
Cm - Oxalic Acid Electrolytic EtchDf - Austenite
Micrography, by optical microscope, of the longitudinal section of a damaged bolt, in the center of the thickness. The microstructure is austenitic, free from carbides, strain hardened. The hardness values of the material are from 200HV1 to 300HV1, that meets the class 2 of strenght (ASTM A193 B8M class 2).
79
VIEW
ML00157 / Feb.2020
Bolts Under Chloride SCC Conditions
M - Austenitic Stainless SteelP - BoltAp - Oil and GasCd - Stress Corrosion
Cm - Nital Etched Micrography by OMDf - Strain Hardened
Detail of the strain hardened austenitic microstructure. Micrography by optical microscope, of the longitudinal section of a bolt, in the center of the thickness.
76
VIEW
ML00157 / Feb.2020
Bolts Under Chloride SCC Conditions
M - Austenitic Stainless SteelP - BoltAp - Oil and GasCd - Stress Corrosion
Cm - Oxalic Acid Electrolytic EtchDf - Strain Hardened
Aspect of a broken 5/16" bolt that was operating inside the pressure vessel in a condition that exceeds the limits of use of the AISI 316 steel. The fracture is located close to the position where there was the bolt head and the threads were "removed" close to the fracture surface.
75
VIEW
ML00157 / Feb.2020
Bolts Under Chloride SCC Conditions
M - Austenitic Stainless SteelP - BoltAp - Oil and GasCd - Stress Corrosion
Cm - Aspect Before AnalysisDf - Fracture

+8 more from this case →

ML00130 — Fatigue Fracture of Overloaded BoltsM - Low Alloy Medium Carbon QTP - FastenerAp - O&G Well DrillingCd - Mechanical Fatigue
The four bolts have fractured in the same position, close to the end, and the corrosion marks in the thread suggest that they have been tightened only a few fillets in a tapped hole. This condition could be responsible for overloading the fillets, relaxing the applied bolt preload, and intensifying cyclic stresses.
192
VIEW
ML00130 / Jun.2018
Fatigue Fracture of Overloaded Bolts
M - Low Alloy Medium Carbon QTP - FastenerAp - O&G Well DrillingCd - Mechanical Fatigue
Cm - Aspect Before AnalysisDf - General View
The corrosion marks in the thread surface indicate that the bolt was not properly tightened in the tapped hole. The length of thread engagement should be at least 1x of the bolt diameter, in this case 3/8".
170
VIEW
ML00130 / Jun.2018
Fatigue Fracture of Overloaded Bolts
M - Low Alloy Medium Carbon QTP - FastenerAp - O&G Well DrillingCd - Mechanical Fatigue
Cm - Aspect Before AnalysisDf - General View
Macroscopic aspect of the bolt fracture. Part of it is flat from the bottom of the thread.
166
VIEW
ML00130 / Jun.2018
Fatigue Fracture of Overloaded Bolts
M - Low Alloy Medium Carbon QTP - FastenerAp - O&G Well DrillingCd - Mechanical Fatigue
Cm - Aspect Before AnalysisDf - Fracture
The head of the bolts presented the marks that indicated they were manufactured to meet ASTM A449 type 1 bolt, that is a medium strength low alloy steel, quenched and tempered.
148
VIEW
ML00130 / Jun.2018
Fatigue Fracture of Overloaded Bolts
M - Low Alloy Medium Carbon QTP - FastenerAp - O&G Well DrillingCd - Mechanical Fatigue
Cm - Aspect Before AnalysisDf - At the Surface
Aspect of the fracture surface in low magnification, showing a flat aspect (associated to a fatigue fracture micromechanims) and a rough aspect (associated to a ductile fracture micromechanism).
167
VIEW
ML00130 / Jun.2018
Fatigue Fracture of Overloaded Bolts
M - Low Alloy Medium Carbon QTP - FastenerAp - O&G Well DrillingCd - Mechanical Fatigue
Cm - Fractography by SEMDf - General View

+12 more from this case →

ML00106 — Inconel 718 Submarine BoltM - NiCrFe AlloyP - BoltAp - SubseaCd - Typical manufacturing
Micrography of a longitudinal section in the center of the bolt. Granular austenitic microstructure, equiaxial, primary precipitates (isolated), precipitation hardened (not detectable by metalography, only because of the hardness level)
63
VIEW
ML00106 / Dec.2017
Inconel 718 Submarine Bolt
M - NiCrFe AlloyP - BoltAp - SubseaCd - Typical manufacturing
Cm - Kalling Etched Micrography by OMDf - Longitudinal Section
Aspect of the bolt analyzed to qualify the lot of fasteners to be adopted in subsea conditions, exposed to cathodic protection.
62
VIEW
ML00106 / Dec.2017
Inconel 718 Submarine Bolt
M - NiCrFe AlloyP - BoltAp - SubseaCd - Typical manufacturing
Cm - Aspect Before AnalysisDf - General View
Low magnification micrography of the bolt in a longitudinal section, at the bolt thread, showing no evidences of forming operations, indicating that it was machined from a heat treated bar. Austenitic microstructure, granular, equiaxial.
54
VIEW
ML00106 / Dec.2017
Inconel 718 Submarine Bolt
M - NiCrFe AlloyP - BoltAp - SubseaCd - Typical manufacturing
Cm - Kalling Etched Micrography by OMDf - Longitudinal Section
Micrography of the bolt in a longitudinal section, at the bolt thread, showing no evidences of forming operations, indicating that it was machined from a heat treated bar. Austenitic microstructure, granular, equiaxial.
49
VIEW
ML00106 / Dec.2017
Inconel 718 Submarine Bolt
M - NiCrFe AlloyP - BoltAp - SubseaCd - Typical manufacturing
Cm - Kalling Etched Micrography by OMDf - Machined Thread
ML00105 — Inconel 718 Bolt of Special HeadM - NiCrFe AlloyP - FastenerAp - SubseaCd - Typical manufacturing
Low magnification micrography of the bolt in a longitudinal section, at the bolt thread, showing no evidences of forming operations, indicating it was machined from a heat treated bar. Austenitic microstructure, granular, equiaxial, precipitation hardened (shadow in the grains).
45
VIEW
ML00105 / Jun.2018
Inconel 718 Bolt of Special Head
M - NiCrFe AlloyP - FastenerAp - SubseaCd - Typical manufacturing
Cm - Kalling Etched Micrography by OMDf - Longitudinal Section
Micrography of the bolt in a longitudinal section, at the bolt thread, showing no evidences of forming operations, indicating it was machined from a heat treated bar. Austenitic microstructure, granular, equiaxial, precipitation hardened (shadow in the grains).
39
VIEW
ML00105 / Jun.2018
Inconel 718 Bolt of Special Head
M - NiCrFe AlloyP - FastenerAp - SubseaCd - Typical manufacturing
Cm - Kalling Etched Micrography by OMDf - Machined Thread
Micrographic detail of the bolt in a longitudinal section, at the bolt thread, showing no evidences of forming operations, indicating it was machined from a heat treated bar. Austenitic microstructure, granular, equiaxial, precipitation hardened (shadow in the grains).
31
VIEW
ML00105 / Jun.2018
Inconel 718 Bolt of Special Head
M - NiCrFe AlloyP - FastenerAp - SubseaCd - Typical manufacturing
Cm - Kalling Etched Micrography by OMDf - Machined Thread
Low magnification micrography of the bolt in a longitudinal section, at the bolt head, showing no evidences of forming operations, indicating it was machined from a heat treated bar. Austenitic microstructure, granular, equiaxial, precipitation hardened (shadow in the grains).
31
VIEW
ML00105 / Jun.2018
Inconel 718 Bolt of Special Head
M - NiCrFe AlloyP - FastenerAp - SubseaCd - Typical manufacturing
Cm - Kalling Etched Micrography by OMDf - Longitudinal Section
Micrography of the bolt in a longitudinal section, at the bolt head, showing no evidences of forming operations, indicating it was machined from a heat treated bar. Austenitic microstructure, granular, equiaxial, precipitation hardened (shadow in the grains).
31
VIEW
ML00105 / Jun.2018
Inconel 718 Bolt of Special Head
M - NiCrFe AlloyP - FastenerAp - SubseaCd - Typical manufacturing
Cm - Kalling Etched Micrography by OMDf - Austenite

+4 more from this case →

ML00101 — High Strength 316SS BoltM - Austenitic Stainless SteelP - BoltAp - SubseaCd - Typical manufacturing
Micrography of the longitudinal section of the bolt, in the center of the body thickness. Strain hardened austenic structure.
52
VIEW
ML00101 / Nov.2017
High Strength 316SS Bolt
M - Austenitic Stainless SteelP - BoltAp - SubseaCd - Typical manufacturing
Cm - Micrography by OM using A262 Method ADf - Strain Hardened
Micrography of the longitudinal section of the bolt, in the center of the body thickness. Strain hardened austenic structure.
46
VIEW
ML00101 / Nov.2017
High Strength 316SS Bolt
M - Austenitic Stainless SteelP - BoltAp - SubseaCd - Typical manufacturing
Cm - Micrography by OM using A262 Method ADf - Strain Hardened
Aspect of the bolts M12 x 25.
41
VIEW
ML00101 / Nov.2017
High Strength 316SS Bolt
M - Austenitic Stainless SteelP - BoltAp - SubseaCd - Typical manufacturing
Cm - Aspect Before AnalysisDf - General View
Micrography of the longitudinal section of the bolt, at the thread. The bolt was cold deformed and the thread was cold rolled.
32
VIEW
ML00101 / Nov.2017
High Strength 316SS Bolt
M - Austenitic Stainless SteelP - BoltAp - SubseaCd - Typical manufacturing
Cm - Micrography by OM using A262 Method ADf - Strain Hardened
Micrography of the longitudinal section of the bolt, at the thread. The bolt was cold deformed and the thread was cold rolled.
31
VIEW
ML00101 / Nov.2017
High Strength 316SS Bolt
M - Austenitic Stainless SteelP - BoltAp - SubseaCd - Typical manufacturing
Cm - Micrography by OM using A262 Method ADf - Strain Hardened

+1 more from this case →

ML00087 — High Strength Austenitic SS BoltM - Austenitic Stainless SteelP - BoltAp - SubseaCd - Typical manufacturing
Micrography of the longitudinal section of the bolt, in the center of the body thickness. Strain hardened austenic structure.
73
VIEW
ML00087 / Nov.2017
High Strength Austenitic SS Bolt
M - Austenitic Stainless SteelP - BoltAp - SubseaCd - Typical manufacturing
Cm - Micrography by OM using A262 Method ADf - Strain Hardened
Micrography of the longitudinal section of the bolt, in the center of the body thickness. Strain hardened austenic structure.
62
VIEW
ML00087 / Nov.2017
High Strength Austenitic SS Bolt
M - Austenitic Stainless SteelP - BoltAp - SubseaCd - Typical manufacturing
Cm - Micrography by OM using A262 Method ADf - Strain Hardened
Socket head capscrew bolt, M10 x 70, 1.5 coarse thread.
63
VIEW
ML00087 / Nov.2017
High Strength Austenitic SS Bolt
M - Austenitic Stainless SteelP - BoltAp - SubseaCd - Typical manufacturing
Cm - Aspect Before AnalysisDf - General View
Micrography of the longitudinal section of the bolt, at the thread. The bolt was cold deformed and the thread was cold rolled.
65
VIEW
ML00087 / Nov.2017
High Strength Austenitic SS Bolt
M - Austenitic Stainless SteelP - BoltAp - SubseaCd - Typical manufacturing
Cm - Micrography by OM using A262 Method ADf - Strain Hardened
Micrography of the longitudinal section of the bolt, at the thread. The bolt was cold deformed and the thread was cold rolled.
65
VIEW
ML00087 / Nov.2017
High Strength Austenitic SS Bolt
M - Austenitic Stainless SteelP - BoltAp - SubseaCd - Typical manufacturing
Cm - Micrography by OM using A262 Method ADf - Strain Hardened

+1 more from this case →

ML00089 — Inconel 718 Allen Bolt for Subsea ApplicationM - NiCrFe AlloyP - Machined PartAp - SubseaCd - Typical manufacturing
The macrography shows the longitudinal section of the allen bolt, 1/2" nominal diameter, that was machined from a heat treated bar (solution annealed and aged). The granular structure presents differences in the grain sizes. At the bolt head (external surface of the original bar) the austenitic grain size is larger than in the center of the bar where the particles in segregated bands "arrested" the grains during hot forming and solution annealing.
58
VIEW
ML00089 / Sep.2017
Inconel 718 Allen Bolt for Subsea Application
M - NiCrFe AlloyP - Machined PartAp - SubseaCd - Typical manufacturing
Cm - Kalling Etched MacroDf - Machined Thread
The micrography of a longitudinal section of the bolt close to the surface, at the thread, shows that it was machined from a bar, not rolled.
37
VIEW
ML00089 / Sep.2017
Inconel 718 Allen Bolt for Subsea Application
M - NiCrFe AlloyP - Machined PartAp - SubseaCd - Typical manufacturing
Cm - Kalling Etched Micrography by OMDf - Machined Thread
The micrography of a longitudinal section of the bolt, in the center of the thickness (ND 1/2"), shows an equiaxial granular structure. Although the material was hardened by heat treatment (solution annealing and aging), the microstructure at this magnification does not reveal the intragranular precipitation.
34
VIEW
ML00089 / Sep.2017
Inconel 718 Allen Bolt for Subsea Application
M - NiCrFe AlloyP - Machined PartAp - SubseaCd - Typical manufacturing
Cm - Kalling Etched Micrography by OMDf - Equiaxial Grains
Micrographic detail of a longitudinal section of the bolt, in the center of the thickness (ND 1/2"). Although the material was hardened by heat treatment (solution annealing and aging), the microstructure observed by optical microscopy does not reveal the intragranular precipitation.
33
VIEW
ML00089 / Sep.2017
Inconel 718 Allen Bolt for Subsea Application
M - NiCrFe AlloyP - Machined PartAp - SubseaCd - Typical manufacturing
Cm - Kalling Etched MacroDf - Austenite
The micrography of a longitudinal section, at the bolt head close to the surface of the original bar. In this region the material increased the grain size due to the lack of particles (inclusions), to "arrest" the grain boundaries (during hot forming and solution annealing). The smaller grain size is located in the center of the bar, that concentrated the inclusions.
30
VIEW
ML00089 / Sep.2017
Inconel 718 Allen Bolt for Subsea Application
M - NiCrFe AlloyP - Machined PartAp - SubseaCd - Typical manufacturing
Cm - Kalling Etched MacroDf - Dual grain sizes

+1 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