Low Alloy Steel

6 cases · 88 images

Crevice Corrosion in a Subsea System — Aspect Before Analysis

Microstructure: Bainite clear all

Low Alloy Steel — sub-branches

High Strength Low Alloy 1Low Alloy Low Carbon QT 1Low Alloy Medium Carbon QT 1Low Alloy for Thermochemical Treatment 1

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Shaft pinion presenting the bearing surface, with machining markes, from where the thermal spray layer was detached. The diameter of the 880 mm long shaft in this region is about 75 mm.
426
VIEW
ML00108 / Dec.2017
Thermal Spray Layer in a Pinion Shaft
M - High Strength Low AlloyP - ShaftAp - EngineCd - Coating Defect
Cm - Aspect Before AnalysisDf - General View
Macrography of the tubular forging, butt welded using a LAS filler metal, and overlaid using Inconel 625 filler metal. The micrographic characterization was conducted for the HAZ of the overlay and for the HAZ of the butt weld, at the root position (with several welding cycles) and at the face.
608
VIEW
ML00102 / May.2018
AISI 4130 Forging Welded and Overlaid
M - Low Alloy SteelP - CladdingAp - Oil and GasCd - Welding
Cm - Electrolytically Etched MacroDf - Welded Joint
Scanning electron fractography of a chromium plated pin, close to the pin surface where the fatigue cracking started, showing intergranular morphology typical of a hydrogen embrittlement effect. It occurred because the low alloy pin was carburized, quenched and tempered, with a too high hardness structure, before the electrolytic plating.
837
VIEW
ML00081 / Aug.2017
Hydrogen Cracking of a Chromium Plated Carburized Pin
M - Low Alloy for Thermochemical TreatmentP - Chromium PlatedAp - AutomotiveCd - Hydrogen Embrittlement
Cm - Fractography by SEMDf - Brittle Fracture
The macrography of a longitudinal section of the pipe and connector, at the welded joint, shows that the welding was conducted from both side of the groove, starting from the ID and finishing from the OD, ID later machined flush. The cracking was detected by ultrasonic test and the macro shows that it is at the fusion line, growthing into the weld metal. See the schematic drawing in the next figure
535
VIEW
ML00072 / Jan.2018
Liquation Cracks in a High Strength Joint
M - Low Alloy Medium Carbon QTP - Longitudinal Seam Welded PipeAp - O&G Well DrillingCd - Welding Defect
Cm - NItal Etched MacroDf - Longitudinal Section
Macrography showing the different regions of a pipe-to-plate fillet weld. See the schematic drawing in the next image
954
VIEW
ML00052 / Apr.2017
Cold Cracks in API 5CT L80 Tube Welded to a Structural Part
M - Low Alloy SteelP - Seamless tubeAp - OffshoreCd - Welding Defect
Cm - NItal Etched MacroDf - Fracture
Mooring chain aspect, after several years of operation. Transverse cracking, revealed by dye check, close to the flash butt weld.
441
VIEW
ML00013 / Apr.2017
Welding Cracks in Mooring Chain
M - Low Alloy Low Carbon QTP - Welded PartAp - OffshoreCd - Welding Defect
Cm - Aspect by NDTDf - Crack

More from these cases

ML00108 — Thermal Spray Layer in a Pinion ShaftM - High Strength Low AlloyP - ShaftAp - EngineCd - Coating Defect
Detail of the detached layer, about 1.5 mm thick.
48
VIEW
ML00108 / Dec.2017
Thermal Spray Layer in a Pinion Shaft
M - High Strength Low AlloyP - ShaftAp - EngineCd - Coating Defect
Cm - Aspect Before AnalysisDf - Layer Detachment
Macrographic detail of the thermal spray layer in a position of the shaft where it was not detached. Longitudinal section of the shaft. The waves are the machining marks created to anchor the thermal spray layer, that is about 1.5mm thick.
41
VIEW
ML00108 / Dec.2017
Thermal Spray Layer in a Pinion Shaft
M - High Strength Low AlloyP - ShaftAp - EngineCd - Coating Defect
Cm - NItal Etched MacroDf - Longitudinal Section
Micrography of the thermal spray (TS) layer showing the different alloys, gray oxides and black voids. The Ni base TS alloy is of a yellow colour at the interface with the shaft substrate (in the left). The Cr base TS alloy appears white, similar to the shaft substrate. Longitudinal section of the shaft.
42
VIEW
ML00108 / Dec.2017
Thermal Spray Layer in a Pinion Shaft
M - High Strength Low AlloyP - ShaftAp - EngineCd - Coating Defect
Cm - As polished micrographyDf - Coating Layer
Micrographic detail, as polished in a longitudinal section, of the interface between the shaft substrate and the thermal spray layer. In the left it is the shaft substrate also presenting parts of aligned inclusions (gray). In the center it is the Ni base TS alloy and in the right it is the Cr base TS alloy. There are also black voids and grey oxides.
33
VIEW
ML00108 / Dec.2017
Thermal Spray Layer in a Pinion Shaft
M - High Strength Low AlloyP - ShaftAp - EngineCd - Coating Defect
Cm - As polished micrographyDf - Coating Layer
Micrography of the interface between the shaft surface and the thermal spray layer. The shaft steel presents a quenched and tempered structure. Longitudinal section.
32
VIEW
ML00108 / Dec.2017
Thermal Spray Layer in a Pinion Shaft
M - High Strength Low AlloyP - ShaftAp - EngineCd - Coating Defect
Cm - Nital Etched Micrography by OMDf - Coating Layer

+7 more from this case →

ML00102 — AISI 4130 Forging Welded and OverlaidM - Low Alloy SteelP - CladdingAp - Oil and GasCd - Welding
Micrography of the 4130 steel, normalized and tempered. The structure is sligthly banded (segregated) and the average hardness level is 20 HRc.
92
VIEW
ML00102 / May.2018
AISI 4130 Forging Welded and Overlaid
M - Low Alloy SteelP - CladdingAp - Oil and GasCd - Welding
Cm - Nital Etched Micrography by OMDf - Base Metal
Micrography of the 4130 steel, normalized and tempered. The microstructure is bainitic.
88
VIEW
ML00102 / May.2018
AISI 4130 Forging Welded and Overlaid
M - Low Alloy SteelP - CladdingAp - Oil and GasCd - Welding
Cm - Nital Etched Micrography by OMDf - Base Metal
Micrographic detail of the bainitic structure of the 4130 steel, normalized and tempered.
87
VIEW
ML00102 / May.2018
AISI 4130 Forging Welded and Overlaid
M - Low Alloy SteelP - CladdingAp - Oil and GasCd - Welding
Cm - Nital Etched Micrography by OMDf - Bainite
Micrography of the tubular 4130 forging at the heat affected zone (HAZ) of the Inconel overlay (white because it was not etched with the Nital). The structure is ferritic/bainitic because the overlay was conducted in two layers, and all the HAZ was reheated during welding.
66
VIEW
ML00102 / May.2018
AISI 4130 Forging Welded and Overlaid
M - Low Alloy SteelP - CladdingAp - Oil and GasCd - Welding
Cm - Nital Etched Micrography by OMDf - Heat Affected Zone
Micrography of the tubular 4130 forging at the heat affected zone (HAZ) of the Inconel overlay (white because it was not etched with the Nital). The structure is ferritic/bainitic because the overlay was conducted in two layers, and all the HAZ was reheated during welding.
61
VIEW
ML00102 / May.2018
AISI 4130 Forging Welded and Overlaid
M - Low Alloy SteelP - CladdingAp - Oil and GasCd - Welding
Cm - Nital Etched Micrography by OMDf - Heat Affected Zone

+7 more from this case →

ML00081 — Hydrogen Cracking of a Chromium Plated Carburized PinM - Low Alloy for Thermochemical TreatmentP - Chromium PlatedAp - AutomotiveCd - Hydrogen Embrittlement
Aspect of three pins that were operating in a hydraulic system. Adjacent to the fracture of the broken pin (the one that is in the right side of the figure) it is possible to see multiple surface craks and detachment of the surface chromium layer.
88
VIEW
ML00081 / Aug.2017
Hydrogen Cracking of a Chromium Plated Carburized Pin
M - Low Alloy for Thermochemical TreatmentP - Chromium PlatedAp - AutomotiveCd - Hydrogen Embrittlement
Cm - Aspect Before AnalysisDf - General View
The aspect of the pin fracture surface shows that a fatigue crack propagated from the pin surface at the edge of a lubrication hole in the chromium plated pin.
83
VIEW
ML00081 / Aug.2017
Hydrogen Cracking of a Chromium Plated Carburized Pin
M - Low Alloy for Thermochemical TreatmentP - Chromium PlatedAp - AutomotiveCd - Hydrogen Embrittlement
Cm - Aspect Before AnalysisDf - Fatigue Fracture
Micrography of a longitudinal section of the pin, in the center. The low carbon content of the steel in the center of the pin makes the structure bainitic even though it was quenched and tempered after carburizing.
80
VIEW
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 Micrography by OMDf - In the Center of the Thickness
Micrographic detail of the bainitic structure in the center of the pin, that was quenched and tempered after carburizing.
75
VIEW
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 Micrography by OMDf - Bainite
Micrography of a longitudinal section of the pin, at the surface. The pin was carburized, quenched and tempered (yellow diffuse layer at the surface, 0.5 mm of extension) and a white layer of hard chromium plating is evident.
108
VIEW
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 Micrography by OMDf - Carburized Layer

+11 more from this case →

ML00072 — Liquation Cracks in a High Strength JointM - Low Alloy Medium Carbon QTP - Longitudinal Seam Welded PipeAp - O&G Well DrillingCd - Welding Defect
Schematic drawing presenting the longitudinal section of the pipe and connector at the welded joint
105
VIEW
ML00072 / Jan.2018
Liquation Cracks in a High Strength Joint
M - Low Alloy Medium Carbon QTP - Longitudinal Seam Welded PipeAp - O&G Well DrillingCd - Welding Defect
Cm - Identification drawingDf - Longitudinal Section
Hot cracking at the fusion line of the connector side, in a welded joint between a forging and a pipe, in a macrographic sample. The region of the heat affected zone of the connector presents a dendritic aspect suggesting that the forging reduction rate of the connector was not too high and did not broke the cast structure.
110
VIEW
ML00072 / Jan.2018
Liquation Cracks in a High Strength Joint
M - Low Alloy Medium Carbon QTP - Longitudinal Seam Welded PipeAp - O&G Well DrillingCd - Welding Defect
Cm - NItal Etched MacroDf - Welded Joint
The connector was welded to the pipe from both (internal and external) sides, a PWHT was applied and the part was machined. The UT indication was detected during final inspection.
78
VIEW
ML00072 / Jan.2018
Liquation Cracks in a High Strength Joint
M - Low Alloy Medium Carbon QTP - Longitudinal Seam Welded PipeAp - O&G Well DrillingCd - Welding Defect
Cm - Aspect Before AnalysisDf - General View
Micrography of the welded joint fusion line presenting the liquation cracking. The weld metal is in the right side (bottom) and the forged connector heat affected zone is in the left side (top).
83
VIEW
ML00072 / Jan.2018
Liquation Cracks in a High Strength Joint
M - Low Alloy Medium Carbon QTP - Longitudinal Seam Welded PipeAp - O&G Well DrillingCd - Welding Defect
Cm - Nital Etched Micrography by OMDf - Cracking
The liquation crack is a hot crack in the base metal (at the HAZ) that induces a solidification crack in the weld metal.
66
VIEW
ML00072 / Jan.2018
Liquation Cracks in a High Strength Joint
M - Low Alloy Medium Carbon QTP - Longitudinal Seam Welded PipeAp - O&G Well DrillingCd - Welding Defect
Cm - Nital Etched Micrography by OMDf - Weld Metal

+11 more from this case →

ML00052 — Cold Cracks in API 5CT L80 Tube Welded to a Structural PartM - Low Alloy SteelP - Seamless tubeAp - OffshoreCd - Welding Defect
Schematic drawing presenting the different regions of a pipe-to-plate fillet weld.
71
VIEW
ML00052 / Apr.2017
Cold Cracks in API 5CT L80 Tube Welded to a Structural Part
M - Low Alloy SteelP - Seamless tubeAp - OffshoreCd - Welding Defect
Cm - Identification drawingDf - Fracture
Macrography of the fillet welded joint between the 3" ND tube and the 3/4" thick plate. See the schematic drawing in the next figure
56
VIEW
ML00052 / Apr.2017
Cold Cracks in API 5CT L80 Tube Welded to a Structural Part
M - Low Alloy SteelP - Seamless tubeAp - OffshoreCd - Welding Defect
Cm - NItal Etched MacroDf - Welded Joint
Schematic drawing presenting the position of the cracking, at the margin of the weld in the tube and underbead.
47
VIEW
ML00052 / Apr.2017
Cold Cracks in API 5CT L80 Tube Welded to a Structural Part
M - Low Alloy SteelP - Seamless tubeAp - OffshoreCd - Welding Defect
Cm - Identification drawingDf - Welded Joint
The micrography shows the region underbead, of the tube HAZ, responsible for the hydrogen cracking (fracture in the right side of the photo - black). The hardness of the HAZ is about 600 HV.
55
VIEW
ML00052 / Apr.2017
Cold Cracks in API 5CT L80 Tube Welded to a Structural Part
M - Low Alloy SteelP - Seamless tubeAp - OffshoreCd - Welding Defect
Cm - Nital Etched Micrography by OMDf - Cracking
Low carbon plate base metal presenting the ferritic perlitic structure.
55
VIEW
ML00052 / Apr.2017
Cold Cracks in API 5CT L80 Tube Welded to a Structural Part
M - Low Alloy SteelP - Seamless tubeAp - OffshoreCd - Welding Defect
Cm - Nital Etched Micrography by OMDf - Base Metal

+13 more from this case →

ML00013 — Welding Cracks in Mooring ChainM - Low Alloy Low Carbon QTP - Welded PartAp - OffshoreCd - Welding Defect
Micrography of a longitudinal section of the mooring chain in the base metal. The low magnification reveals the banded structure of the rolled bar. The base metal microstructure is bainitic..
79
VIEW
ML00013 / Apr.2017
Welding Cracks in Mooring Chain
M - Low Alloy Low Carbon QTP - Welded PartAp - OffshoreCd - Welding Defect
Cm - Nital Etched Micrography by OMDf - Banded Structure
Micrographic detail of the bainitic microstructure of the base metal in the longitudinal section.
72
VIEW
ML00013 / Apr.2017
Welding Cracks in Mooring Chain
M - Low Alloy Low Carbon QTP - Welded PartAp - OffshoreCd - Welding Defect
Cm - Nital Etched Micrography by OMDf - Bainite
Micrography of a longitudinal section of the mooring chain at the flash welded region. The banded structure is deformed by the upset, close to the weld metal that is ferritic-bainitic.
61
VIEW
ML00013 / Apr.2017
Welding Cracks in Mooring Chain
M - Low Alloy Low Carbon QTP - Welded PartAp - OffshoreCd - Welding Defect
Cm - Nital Etched Micrography by OMDf - Bainitic Ferrite
Micrographic detail of the ferritic-bainitic weld metal, autogenous flash butt weld.
56
VIEW
ML00013 / Apr.2017
Welding Cracks in Mooring Chain
M - Low Alloy Low Carbon QTP - Welded PartAp - OffshoreCd - Welding Defect
Cm - Nital Etched Micrography by OMDf - Bainitic Ferrite
Welded region etched to reveal impurities. The banded structure creates a continuous network parallel to the weld metal.
50
VIEW
ML00013 / Apr.2017
Welding Cracks in Mooring Chain
M - Low Alloy Low Carbon QTP - Welded PartAp - OffshoreCd - Welding Defect
Cm - Micro by OM, picric acid+FeCl3+H2O etchDf - Segregated Regions

+3 more from this case →