As polished micrography

3 cases · 13 images

Crevice Corrosion in a Subsea System — Aspect Before Analysis

Standard: 4130 clear all

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Micrography of the longitudinal section of the bolt at the bottom of the thread fillet, in the "as polished" condition, showing the zinc flakes coating layer, applied by a painting process that do not create metallurgical bonding with the substrate.
82
VIEW
ML00126 / Mar.2018
Hydrogen Fracture of Subsea Allen Bolts
M - Low Alloy Medium Carbon QTP - Coated ProductAp - SubseaCd - Hydrogen Embrittlement
Cm - As polished micrographyDf - Coating Layer
Micrography, as polished, of the transverse section of the forged pin with the layer applied by a (thermal) spray and fuse process. The layer presented entrapped pores and globular oxides. It was melted after application by thermal spray (in this case using a flame) but the pin was not heat treated after the full application and melting of the layer and the base metal is ferritc-pearlitic.
51
VIEW
ML00110 / Jan.2018
Non Conformance in Spray and Fuse Pin
M - Low Alloy Medium Carbon QTP - Tubular ForgingAp - O&G Well DrillingCd - Heat Treatment Defect
Cm - As polished micrographyDf - Transverse Section
Micrography, as polished, of the transverse section of the forged pin with the layer applied by a (thermal) spray and fuse process. The structure of the layer that is 0.7 mm thick, presented entrapped pores and globular oxides. The layer was melted after application by thermal spray (in this case using a flame) and the pin was quenched and tempered after the full application and melting of the layer.
360
VIEW
ML00109 / Jan.2018
Thermal Spray and Fuse Layer in Forged Pin
M - Low Alloy Medium Carbon QTP - Tubular ForgingAp - O&G Well DrillingCd - Thermal spray
Cm - As polished micrographyDf - Transverse Section

More from these cases

ML00126 — Hydrogen Fracture of Subsea Allen BoltsM - Low Alloy Medium Carbon QTP - Coated ProductAp - SubseaCd - Hydrogen Embrittlement
Micrographic detail of the zinc flakes coating layer in the "as polished" condition of a longitudinal section of the bolt.
71
VIEW
ML00126 / Mar.2018
Hydrogen Fracture of Subsea Allen Bolts
M - Low Alloy Medium Carbon QTP - Coated ProductAp - SubseaCd - Hydrogen Embrittlement
Cm - As polished micrographyDf - Coating Layer
Micrography of the longitudinal section of the bolt, at the fracture (top of the figure), starting from the bottom of the thread (to the left side of the figure). The presence of the coating at the bolt surface shows that the fracture occurred without corrosion. The rusted aspect of the fracture is associated to corrosion products after the rupture has occurred, also suggesting that the bolts were fractured and remained in service for some time after the failure occurred.
65
VIEW
ML00126 / Mar.2018
Hydrogen Fracture of Subsea Allen Bolts
M - Low Alloy Medium Carbon QTP - Coated ProductAp - SubseaCd - Hydrogen Embrittlement
Cm - As polished micrographyDf - Fracture
ML00110 — Non Conformance in Spray and Fuse PinM - Low Alloy Medium Carbon QTP - Tubular ForgingAp - O&G Well DrillingCd - Heat Treatment Defect
Micrography, as polished, of the transverse section of the forged pin with the layer applied by a (thermal) spray and fuse process. The layer was melted after thermal spray application and the layer presents a continuous matrix, but there are globular oxides and pores entrapped.
36
VIEW
ML00110 / Jan.2018
Non Conformance in Spray and Fuse Pin
M - Low Alloy Medium Carbon QTP - Tubular ForgingAp - O&G Well DrillingCd - Heat Treatment Defect
Cm - As polished micrographyDf - Surface Layer
Micrographic detail, as polished, of the transverse section of the forged pin at the interface between the pin and the spray and fuse layer. The interface presents globular oxides and small pores, entrapped.
35
VIEW
ML00110 / Jan.2018
Non Conformance in Spray and Fuse Pin
M - Low Alloy Medium Carbon QTP - Tubular ForgingAp - O&G Well DrillingCd - Heat Treatment Defect
Cm - As polished micrographyDf - Surface Layer
Low magnification micrography of the interface between the pin and the spray and fuse layer. Close to the surface, under the layer, the pin presents a ferritic perlitic structure, non conform with the high strenght requirement. Transverse section.
37
VIEW
ML00110 / Jan.2018
Non Conformance in Spray and Fuse Pin
M - Low Alloy Medium Carbon QTP - Tubular ForgingAp - O&G Well DrillingCd - Heat Treatment Defect
Cm - As polished micrographyDf - Low Mag
Micrography, as polished, of the transverse section of the forged pin, showing a crack in the thermal spray layer, thickness about 0.8mm. The spray and fuse process was conducted in a low alloy steel, type AISI 4130, but the quenching and tempering heat treatment was not applied later, and the pin body presented low strenght, evidencing plastic deformation after hydrostatic testing, that cause the layer cracking.
21
VIEW
ML00110 / Jan.2018
Non Conformance in Spray and Fuse Pin
M - Low Alloy Medium Carbon QTP - Tubular ForgingAp - O&G Well DrillingCd - Heat Treatment Defect
Cm - As polished micrographyDf - Cracks Transverse to the Surface
Micrographic detail of the crack in the thermal spray layer. The spray and fuse layer presented a typically melted structure with entrapped pores and globular oxides.
29
VIEW
ML00110 / Jan.2018
Non Conformance in Spray and Fuse Pin
M - Low Alloy Medium Carbon QTP - Tubular ForgingAp - O&G Well DrillingCd - Heat Treatment Defect
Cm - As polished micrographyDf - Crack

+1 more from this case →

ML00109 — Thermal Spray and Fuse Layer in Forged PinM - Low Alloy Medium Carbon QTP - Tubular ForgingAp - O&G Well DrillingCd - Thermal spray
Micrography, as polished, of the transverse section of the forged pin with the layer applied by a (thermal) spray and fuse process. The layer was melted after thermal spray application and the layer presents a continuous matrix, but there are globular oxides and pores entrapped.
29
VIEW
ML00109 / Jan.2018
Thermal Spray and Fuse Layer in Forged Pin
M - Low Alloy Medium Carbon QTP - Tubular ForgingAp - O&G Well DrillingCd - Thermal spray
Cm - As polished micrographyDf - Surface Layer
Micrographic detail, as polished, of the transverse section of the forged pin at the interface between the pin and the spray and fuse layer. The pin was heat treated after the thermal spray, and fuse treatment. The interface presents a higher concentration of globular oxides and pores, entrapped.
23
VIEW
ML00109 / Jan.2018
Thermal Spray and Fuse Layer in Forged Pin
M - Low Alloy Medium Carbon QTP - Tubular ForgingAp - O&G Well DrillingCd - Thermal spray
Cm - As polished micrographyDf - Surface Layer