Low Alloy Steel

24 cases · 269 images

Crevice Corrosion in a Subsea System — Aspect Before Analysis

Standard: ASTM clear all

Low Alloy Steel — sub-branches

CMn Steel 11CrMo Steel 4High Strength Low Alloy 3Low Alloy Low Carbon QT 1Low Alloy Medium Carbon QT 3Microalloyed Steel 1

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The drilling connector, 21" diameter, presented a crack at the margin of the weld in the forging side (left side of the weld in the figure).
744
VIEW
ML00178 / Jan.2022
Cold cracks in Cr-Mo Welded Forging
M - CrMo SteelP - ForgingAp - O&G Well DrillingCd - Welding Defect
Cm - Aspect Before AnalysisDf - General View
Macrography of the longitudinally seam weld of the 24" diameter tube, showing that it was welded from both sides and there is a segregation line in the center of the tube thickness.
737
VIEW
ML00177 / Dec.2021
Cr-Mo Seam Welded Tube
M - CrMo SteelP - Longitudinally Seam WeldedAp - Fired HeaterCd - Not according to spec
Cm - NItal Etched MacroDf - Seam
Aspect of the fracture surface of the 2" diameter casting. The fracture appeared flat, with secondary cracks, and the position of the fracture during the loading test is located in the region that was in tensile stress during the hot dip galvanized process (the part was sustaining its own weight during the zinc hot dip bath).
800
VIEW
ML00138 / Jun.2018
Liquid Metal Embrittlement of a HSLA Steel
M - High Strength Low AlloyP - Coated ProductAp - Mechanical IndustryCd - Liquid Metal Embrittlement
Cm - Aspect Before AnalysisDf - Brittle Fracture
Aspect of the broken stud that was fastening a flanged line in a subsea body (tapped hole) using a nut. The fracture, transverse to the stud axis, occurred exactly at the body to flange interface. Adjacent to the fracture, all thread fillets (positioned inside the flange hole) presented cracks at the bottom of the thread. The stud was operating during seven years and was not corroded, indicating it was protected by the anodes. There are also deposits in the fillets suggesting the cathodic protection was effective even inside the flange hole.
799
VIEW
ML00136 / Jun.2018
Hydrogen Cracks of Subsea Studs
M - Low Alloy Medium Carbon QTP - FastenerAp - SubseaCd - Hydrogen Embrittlement
Cm - Aspect Before AnalysisDf - General View
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 transverse section of the tubing, in the center of the thickness. Ferritic-pearlitic structure. Pearlite colonies in bands.
401
VIEW
ML00116 / Jan.2018
CMn Steel Structural Tubing 6 mm thick
M - CMn SteelP - Seamless Round ShapeAp - StructureCd - Removed From Service
Cm - Nital Etched Micrography by OMDf - Ferrite and Pearlite
Micrographic detail of a transverse section of the 5 mm thick tubing, in the center of the thickness. Ferritic-pearlitic structure, with the pearlite presenting a coalesced aspect. The tubing was in service at ambient temperature, painted, and the coalesced aspect was generated before service, perhaps during the tubing manufacturing.
393
VIEW
ML00115 / Jan.2018
CMn Steel Structural Tubing 5 mm thick
M - CMn SteelP - Seamless Round ShapeAp - StructureCd - Removed From Service
Cm - Nital Etched Micrography by OMDf - Ferrite and Pearlite
Micrographic detail of a transverse section of the tubing, in the center of the thickness. Ferritic-pearlitic structure. Pearlite colonies in bands.
346
VIEW
ML00114 / Jan.2018
CMn Steel Structural Tubing 8 mm thick
M - CMn SteelP - Seamless Round ShapeAp - StructureCd - Removed From Service
Cm - Nital Etched Micrography by OMDf - Ferrite and Pearlite

More from these cases

ML00178 — Cold cracks in Cr-Mo Welded ForgingM - CrMo SteelP - ForgingAp - O&G Well DrillingCd - Welding Defect
Circumferential weld aspect. Two passes in the cap. This forging to pipe welded joint, 22 mm thick, was welded by an automatic process in a narrow gap. The pipe is to the top of the image and the forging is to the bottom of the image.
165
VIEW
ML00178 / Jan.2022
Cold cracks in Cr-Mo Welded Forging
M - CrMo SteelP - ForgingAp - O&G Well DrillingCd - Welding Defect
Cm - Aspect Before AnalysisDf - External Surface
The dye check image shows the detected crack, 50 mm long, at the margin of the weld in the forging side.
137
VIEW
ML00178 / Jan.2022
Cold cracks in Cr-Mo Welded Forging
M - CrMo SteelP - ForgingAp - O&G Well DrillingCd - Welding Defect
Cm - Aspect by NDTDf - Cracking
Macrography of the welded joint between the forging and the pipe, showing it was welded in a narrow gap, indicating by the arrow the location of the crack at the margin of the weld, in the forging side.
129
VIEW
ML00178 / Jan.2022
Cold cracks in Cr-Mo Welded Forging
M - CrMo SteelP - ForgingAp - O&G Well DrillingCd - Welding Defect
Cm - NItal Etched MacroDf - Welded Joint
Quenched and tempered structure of the F22 steel forging, presenting about 230HV10 average hardness.
133
VIEW
ML00178 / Jan.2022
Cold cracks in Cr-Mo Welded Forging
M - CrMo SteelP - ForgingAp - O&G Well DrillingCd - Welding Defect
Cm - Nital Etched Micrography by OMDf - Base Metal
Tempered martensitic structure for the F22 forging base metal.
129
VIEW
ML00178 / Jan.2022
Cold cracks in Cr-Mo Welded Forging
M - CrMo SteelP - ForgingAp - O&G Well DrillingCd - Welding Defect
Cm - Nital Etched Micrography by OMDf - Tempered Martensite

+14 more from this case →

ML00177 — Cr-Mo Seam Welded TubeM - CrMo SteelP - Longitudinally Seam WeldedAp - Fired HeaterCd - Not according to spec
Identification of the regions of metallographies of the base metal, heat affected zone (HAZ) and weld metal. Locations in the root, in the center of the thickness and close to the tube OD (external surface).
118
VIEW
ML00177 / Dec.2021
Cr-Mo Seam Welded Tube
M - CrMo SteelP - Longitudinally Seam WeldedAp - Fired HeaterCd - Not according to spec
Cm - NItal Etched MacroDf - Welded Joint
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
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

+20 more from this case →

ML00138 — Liquid Metal Embrittlement of a HSLA SteelM - High Strength Low AlloyP - Coated ProductAp - Mechanical IndustryCd - Liquid Metal Embrittlement
Micrography of the high strenght steel, heat treated, of the casting device. The microstructure is bainitic martensitic.
109
VIEW
ML00138 / Jun.2018
Liquid Metal Embrittlement of a HSLA Steel
M - High Strength Low AlloyP - Coated ProductAp - Mechanical IndustryCd - Liquid Metal Embrittlement
Cm - Nital Etched Micrography by OMDf - Bainitic Martensitic
Micrography of the high strenght steel, heat treated, of the casting device. The microstructure is bainitic martensitic.
92
VIEW
ML00138 / Jun.2018
Liquid Metal Embrittlement of a HSLA Steel
M - High Strength Low AlloyP - Coated ProductAp - Mechanical IndustryCd - Liquid Metal Embrittlement
Cm - Nital Etched Micrography by OMDf - Bainitic Martensitic
Micrographic detail of the high strenght steel microstructure, bainitic martensitic.
85
VIEW
ML00138 / Jun.2018
Liquid Metal Embrittlement of a HSLA Steel
M - High Strength Low AlloyP - Coated ProductAp - Mechanical IndustryCd - Liquid Metal Embrittlement
Cm - Nital Etched Micrography by OMDf - Bainitic Martensitic
Micrography of the casting at the surface, presenting a zinc layer deposited in a hot dip process. The thickness of the layer is about 0.3mm in this position, that is higher than expected for this process. The steel substrate is not revealed because the etch was light and the zinc layer protects the low aloy steel during the etch.
93
VIEW
ML00138 / Jun.2018
Liquid Metal Embrittlement of a HSLA Steel
M - High Strength Low AlloyP - Coated ProductAp - Mechanical IndustryCd - Liquid Metal Embrittlement
Cm - Nital Etched Micrography by SEMDf - Zn Layer
Micrographic detail of the zinc layer at the surface.
88
VIEW
ML00138 / Jun.2018
Liquid Metal Embrittlement of a HSLA Steel
M - High Strength Low AlloyP - Coated ProductAp - Mechanical IndustryCd - Liquid Metal Embrittlement
Cm - Nital Etched Micrography by OMDf - Zn Layer

+24 more from this case →

ML00136 — Hydrogen Cracks of Subsea StudsM - Low Alloy Medium Carbon QTP - FastenerAp - SubseaCd - Hydrogen Embrittlement
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
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

+24 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 →

ML00116 — CMn Steel Structural Tubing 6 mm thickM - CMn SteelP - Seamless Round ShapeAp - StructureCd - Removed From Service
Low magnification micrography of a transverse section of the tubing, in the center of the thickness. Ferritic-pearlitic banded structure.
30
VIEW
ML00116 / Jan.2018
CMn Steel Structural Tubing 6 mm thick
M - CMn SteelP - Seamless Round ShapeAp - StructureCd - Removed From Service
Cm - Nital Etched Micrography by OMDf - Banded Structure
Micrography of a transverse section of the tubing, in the center of the thickness. Ferritic-pearlitic structure. Bands of pearlite colonies. Refined grains.
26
VIEW
ML00116 / Jan.2018
CMn Steel Structural Tubing 6 mm thick
M - CMn SteelP - Seamless Round ShapeAp - StructureCd - Removed From Service
Cm - Nital Etched Micrography by OMDf - In the Center of the Thickness
Micrography of a transverse section of the tubing in the center of the thickness. Ferritic-pearlitic structure. The structure is fully ferritic in a small extension at the surface, due to a decarburization effect during manufacturing.
26
VIEW
ML00116 / Jan.2018
CMn Steel Structural Tubing 6 mm thick
M - CMn SteelP - Seamless Round ShapeAp - StructureCd - Removed From Service
Cm - Nital Etched Micrography by OMDf - Close to the External Surface
Micrographic detail of a transverse section of the tubing, close to the internal surface. Ferritic-pearlitic structure, refined.
20
VIEW
ML00116 / Jan.2018
CMn Steel Structural Tubing 6 mm thick
M - CMn SteelP - Seamless Round ShapeAp - StructureCd - Removed From Service
Cm - Nital Etched Micrography by OMDf - Close to the Internal Surface
ML00115 — CMn Steel Structural Tubing 5 mm thickM - CMn SteelP - Seamless Round ShapeAp - StructureCd - Removed From Service
Low magnification micrography of a transverse section of the tubing, in the center of the thickness. Banded structure, ferritic-pearlitic.
16
VIEW
ML00115 / Jan.2018
CMn Steel Structural Tubing 5 mm thick
M - CMn SteelP - Seamless Round ShapeAp - StructureCd - Removed From Service
Cm - Nital Etched Micrography by OMDf - Banded Structure
Micrography of a transverse section of the tubing, in the center of the thickness. Ferritic-pearlitic structure. The pearlite is banded and presented a coalesced aspect.
12
VIEW
ML00115 / Jan.2018
CMn Steel Structural Tubing 5 mm thick
M - CMn SteelP - Seamless Round ShapeAp - StructureCd - Removed From Service
Cm - Nital Etched Micrography by OMDf - In the Center of the Thickness
Micrographic detail of a transverse section of the tubing, at the external surface. Ferritic-pearlitic structure. The roughness of the surface is high because the structure was painted and a blasting treatment was probably applied to the surface to improve adherence.
15
VIEW
ML00115 / Jan.2018
CMn Steel Structural Tubing 5 mm thick
M - CMn SteelP - Seamless Round ShapeAp - StructureCd - Removed From Service
Cm - Nital Etched Micrography by OMDf - Close to the External Surface
Micrographic detail of a transverse section of the tubing, close to the internal surface. Ferritic-pearlitic structure. Very close to the surface the amount of ferrite is higher than in the center and the grain is coarser, due to a decarburization effect probably occurred when the surface was exposed to high temperature during manufacturing.
13
VIEW
ML00115 / Jan.2018
CMn Steel Structural Tubing 5 mm thick
M - CMn SteelP - Seamless Round ShapeAp - StructureCd - Removed From Service
Cm - Nital Etched Micrography by OMDf - Close to the Internal Surface
ML00114 — CMn Steel Structural Tubing 8 mm thickM - CMn SteelP - Seamless Round ShapeAp - StructureCd - Removed From Service
Low magnification micrography of a transverse section of the tubing, in the center of the thickness. Ferritic-pearlitic banded structure.
29
VIEW
ML00114 / Jan.2018
CMn Steel Structural Tubing 8 mm thick
M - CMn SteelP - Seamless Round ShapeAp - StructureCd - Removed From Service
Cm - Nital Etched Micrography by OMDf - Banded Structure
Micrography of a transverse section of the tubing, in the center of the thickness. Ferritic-pearlitic structure. Bands of pearlite colonies. Refined grains.
29
VIEW
ML00114 / Jan.2018
CMn Steel Structural Tubing 8 mm thick
M - CMn SteelP - Seamless Round ShapeAp - StructureCd - Removed From Service
Cm - Nital Etched Micrography by OMDf - In the Center of the Thickness
Micrography of a transverse section of the tubing, at the external surface. Ferritic-pearlitic structure. The roughness of the surface is high because the structure was painted and a blasting treatment was probably applied to the surface to improve adherence.
20
VIEW
ML00114 / Jan.2018
CMn Steel Structural Tubing 8 mm thick
M - CMn SteelP - Seamless Round ShapeAp - StructureCd - Removed From Service
Cm - Nital Etched Micrography by OMDf - Close to the External Surface
Micrography of a transverse section of the tubing, close to the internal surface. Ferritic-pearlitic structure, refined.
16
VIEW
ML00114 / Jan.2018
CMn Steel Structural Tubing 8 mm thick
M - CMn SteelP - Seamless Round ShapeAp - StructureCd - Removed From Service
Cm - Nital Etched Micrography by OMDf - Close to the Internal Surface