Acicular Ferrite

3 cases · 31 images

Crevice Corrosion in a Subsea System — Aspect Before Analysis

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Aspect of the waterwall during removal of the leaking tube. The leakage was detected, by visual inspection, from the outside of the boiler.
1675
VIEW
ML00163 / Jun.2020
Corrosion Fatigue of a Boiler Waterwall Tube
M - Low Carbon SteelP - Seamless tubeAp - BoilerCd - Corrosion Fatigue
Cm - Field photoDf - General View
Macrography of a section longitudinal to the pipe and transverse to the weld. The thickness of the pipe is 12,7 mm (1/2") and it was welded in 6 passes, the root pass, one fill pass and four cap passes.
855
VIEW
ML00153 / Jan.2019
X52 in a Tubular Structure
M - CMn SteelP - Seamless PipeAp - StructureCd - Qualified
Cm - NItal Etched MacroDf - Welded Joint
Micrography of the weld metal, at the face, presenting regions of large ferritic grains. The acicular ferrite structure in the columnar (previous austenitic) grains has suffered degradation due to the long heat treatment cycle (12 hours) in high temperature.
96
VIEW
ML00129 / Apr.2018
Non qualified WPS for High Strength Steel
M - Low Alloy Medium Carbon QTP - Welded Testpiece for QualificationAp - Oil and GasCd - Non qualified
Cm - Nital Etched Micrography by OMDf - Weld Metal

More from these cases

ML00163 — Corrosion Fatigue of a Boiler Waterwall TubeM - Low Carbon SteelP - Seamless tubeAp - BoilerCd - Corrosion Fatigue
Aspect of the tube internal surface after removal from the boiler, presenting multiple longitudinal cracks.
295
VIEW
ML00163 / Jun.2020
Corrosion Fatigue of a Boiler Waterwall Tube
M - Low Carbon SteelP - Seamless tubeAp - BoilerCd - Corrosion Fatigue
Cm - Aspect Before AnalysisDf - Internal Surface
Aspect of the external surface of the leaking tube, after removal of the membrane.
262
VIEW
ML00163 / Jun.2020
Corrosion Fatigue of a Boiler Waterwall Tube
M - Low Carbon SteelP - Seamless tubeAp - BoilerCd - Corrosion Fatigue
Cm - Aspect Before AnalysisDf - External Surface
Micrography of the external tube surface, presenting a crack at the weld margin. This cracking could have been created by thermal induced cycles (fatigue), but it did not propagate into the tube wall. In some regions of the external side of the tube the weld metal was detached.
77
VIEW
ML00163 / Jun.2020
Corrosion Fatigue of a Boiler Waterwall Tube
M - Low Carbon SteelP - Seamless tubeAp - BoilerCd - Corrosion Fatigue
Cm - Nital Etched Micrography by OMDf - External Surface
Micrography of the external tube surface, presenting the cracking at the margin of the weld. This cracking could have been created by thermal induced cycles (fatigue), but it did not propagate into the tube wall.
85
VIEW
ML00163 / Jun.2020
Corrosion Fatigue of a Boiler Waterwall Tube
M - Low Carbon SteelP - Seamless tubeAp - BoilerCd - Corrosion Fatigue
Cm - Nital Etched Micrography by OMDf - Fusion Line
ML00153 — X52 in a Tubular StructureM - CMn SteelP - Seamless PipeAp - StructureCd - Qualified
Micrography of the pipe base metal, in a longitudinal section, presenting a slight banding and a refined structure.
147
VIEW
ML00153 / Jan.2019
X52 in a Tubular Structure
M - CMn SteelP - Seamless PipeAp - StructureCd - Qualified
Cm - Nital Etched Micrography by OMDf - Base Metal
Micrography of the pipe base metal, in a longitudinal section. The ferritic structure is refined and it is possible to identify a small variation in the ferritic grain size, that is promoting the slight banding effect.
119
VIEW
ML00153 / Jan.2019
X52 in a Tubular Structure
M - CMn SteelP - Seamless PipeAp - StructureCd - Qualified
Cm - Nital Etched Micrography by OMDf - Base Metal
Schematic drawing of the API 5L X52 pipe, butt welded to another pipe, showing the 4 cap passes. The pipe is nominal diameter 8" and thickness 1/2". The qualification of the WPS was conducted according to the structural code, with toughness requirements (Charpy V at 0°C), with 4 lateral bending tests, all approved, and 2 welded joint tensile tests, one with ruptured in the base metal and the other ruptured in the weld metal, both presenting strenght level higher than the minimum specified. The pipe was tensile tested.
95
VIEW
ML00153 / Jan.2019
X52 in a Tubular Structure
M - CMn SteelP - Seamless PipeAp - StructureCd - Qualified
Cm - Identification drawingDf - Welded Joint
Micrography of the weded joint at the cap pass fusion line. The columnar structure of the weld metal is to the top of the figure; and it is possible to see the coarse grains at the heat affected zone. Both columnar structure and coarse grains are related to the previous austenite grain boundaries. From the fusion line to the base metal (in the bottom of the figure) the grain sizes are refined.
86
VIEW
ML00153 / Jan.2019
X52 in a Tubular Structure
M - CMn SteelP - Seamless PipeAp - StructureCd - Qualified
Cm - Nital Etched Micrography by OMDf - Welded Joint
Micrography presenting the coarse grain heat affected zone of the welded joint, at the cap pass. The microstructure is bainitic.
82
VIEW
ML00153 / Jan.2019
X52 in a Tubular Structure
M - CMn SteelP - Seamless PipeAp - StructureCd - Qualified
Cm - Nital Etched Micrography by OMDf - Heat Affected Zone

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ML00129 — Non qualified WPS for High Strength SteelM - Low Alloy Medium Carbon QTP - Welded Testpiece for QualificationAp - Oil and GasCd - Non qualified
Micrography of the weld metal, at the face, presenting regions of large ferritic grains. The acicular ferrite has suffered degradation due to the long heat treatment cycle (12 hours) in a temperature of 640°C, that is higher than the recommended for the D2 filler metal.
78
VIEW
ML00129 / Apr.2018
Non qualified WPS for High Strength Steel
M - Low Alloy Medium Carbon QTP - Welded Testpiece for QualificationAp - Oil and GasCd - Non qualified
Cm - Nital Etched Micrography by OMDf - Weld Metal
Macrography of the welded joint taken from the vertical up part of the joint, presenting the root in one pass, the fill of the joint in three passes, the cap in three passes and two temper bead passes. The 10" diameter tube, 9.5mm thick, was welded by GTAW in the root (80SD2 filler metal) and by SMAW for fill, cap and temper bead passes (10018-D2 filler metal).
77
VIEW
ML00129 / Apr.2018
Non qualified WPS for High Strength Steel
M - Low Alloy Medium Carbon QTP - Welded Testpiece for QualificationAp - Oil and GasCd - Non qualified
Cm - NItal Etched MacroDf - Welded Joint
WPS welded in 6G qualification welding position and tested according to ASME IX and NACE ISO 15156. Minimum preheating of 250°C. Two temper bead passes. PWHT at 640°C during 12 hours. Tube diameter 10". Thickness 3/8". V groove 70°. Root opening 1/8". NOT APPROVED due to ULTIMATE STRENGHT lower than the base metal minimum requirements.
87
VIEW
ML00129 / Apr.2018
Non qualified WPS for High Strength Steel
M - Low Alloy Medium Carbon QTP - Welded Testpiece for QualificationAp - Oil and GasCd - Non qualified
Cm - WPS summaryDf - Welded Joint
Aspect of the internal surface of the tube, presenting the aspect of the root, after welding and heat treatment.
63
VIEW
ML00129 / Apr.2018
Non qualified WPS for High Strength Steel
M - Low Alloy Medium Carbon QTP - Welded Testpiece for QualificationAp - Oil and GasCd - Non qualified
Cm - Aspect Before AnalysisDf - Internal Surface
Aspect of the external surface of the tube, presenting the aspect of the cap and temper bead passes, after welding and heat treatment.
54
VIEW
ML00129 / Apr.2018
Non qualified WPS for High Strength Steel
M - Low Alloy Medium Carbon QTP - Welded Testpiece for QualificationAp - Oil and GasCd - Non qualified
Cm - Aspect Before AnalysisDf - External Surface

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