At the Surface

6 cases · 11 images

Crevice Corrosion in a Subsea System — Aspect Before Analysis

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Aspect of one region where the cracks appeared, after grinding and polishing. Several branched cracks located in welded regions. It is the region where the sample was taken.
37
VIEW
ML00174 / Jul.2021
Carburization of a 347 SS Welded Joint
M - Austenitic Stainless SteelP - Fabrication WeldAp - EnergyCd - Carburization
Cm - Aspect Before AnalysisDf - At the Surface
Micrography of a longitudinal section of the tubing where the fracture occurred. the left side is the outer diameter and the right side is the inner diameter.
37
VIEW
ML00167 / Aug.2020
Fatigue of a Flared Tubing Connection
M - Austenitic Stainless SteelP - TubingAp - EngineCd - Mechanical Fatigue
Cm - Oxalic Acid Electrolytic EtchDf - At the Surface
SAMPLE 3, CLOSE TO THE SURFACE OF SIDE A - Micrography, as polished, of the oxides at the process side. In this region there is an oxide layer, not continuous but with no localized penetrations.
43
VIEW
ML00160 / Apr.2020
High Temperature Degradation of 310SS
M - Austenitic Stainless SteelP - Rectangular TubeAp - Chemical IndustryCd - Scaling
Cm - As polished micrographyDf - At the Surface
Micrography of the wheel at the surface that was quenched and tempered. The material presents a tempered martensitic structure, with hardness that varied from 327HB to 363HB.
55
VIEW
ML00158 / Feb.2020
Surface Hardened Carbon Steel Wheel
M - High Carbon SteelP - WheelAp - TransportationCd - Removed From Service
Cm - Nital Etched Micrography by OMDf - At the Surface
Macroscopic aspect of the crack in the valve ring surface. A leakage was detected during testing after 6 months out of service and the inspection identified several transverse cracks in the forged ring. The valve was installed for one year, but it was not drained during the time it was out of service. The cracks were located in regions that were rusted and presenting a biological fouling.
51
VIEW
ML00124 / Feb.2018
MIC of a Martensitic Valve Ring
M - Martensitic Stainless SteelP - ForgingAp - EnergyCd - Brittle Behavior
Cm - Aspect Before AnalysisDf - At the Surface
Micrographic detail a longitudinal section of the pin, at the surface, showing the case hardened. The pin carburized, quenched and tempered structure presents a gradient of carbon content and consequently a gradient of martensitic structure and hardness. Close to the surface the hardness level is 742 HV1 .
87
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 - At the Surface

More from these cases

ML00160 — High Temperature Degradation of 310SSM - Austenitic Stainless SteelP - Rectangular TubeAp - Chemical IndustryCd - Scaling
SAMPLE 3, CLOSE TO THE SURFACE OF SIDE B - Micrography, as polished, of the oxides at the electric furnace environment side. In this region the oxide layer is thinner than in the process side.
46
VIEW
ML00160 / Apr.2020
High Temperature Degradation of 310SS
M - Austenitic Stainless SteelP - Rectangular TubeAp - Chemical IndustryCd - Scaling
Cm - As polished micrographyDf - At the Surface
SAMPLE 1, CLOSE TO THE SURFACE OF SIDE A - Micrography, as polished, of the oxides at the process side. In this region the oxide layer is penetrating into the austenitic grain boundaries, creating a crack like effect.
56
VIEW
ML00160 / Apr.2020
High Temperature Degradation of 310SS
M - Austenitic Stainless SteelP - Rectangular TubeAp - Chemical IndustryCd - Scaling
Cm - As polished micrographyDf - At the Surface
SAMPLE 1 AT 1 mm THICKNESS, SIDE B - Micrographic detail of the austenite with secondary precipitation, close to the surface exposed to the furnace environment. This NaOH electrolytic etch is adopted to colour sigma phase and at this position there are no special formation of sigma in the grain boundaries and there are no oxide penetrations, confirming that the environment is important to create the damage and the internal side of the tube is responsible for the quick degradation in high temperature.
25
VIEW
ML00160 / Apr.2020
High Temperature Degradation of 310SS
M - Austenitic Stainless SteelP - Rectangular TubeAp - Chemical IndustryCd - Scaling
Cm - NaOH Electrolytic Etched MicroDf - At the Surface
ML00158 — Surface Hardened Carbon Steel WheelM - High Carbon SteelP - WheelAp - TransportationCd - Removed From Service
Micrography of the wheel at the hardened surface, presenting a refined martensitic structure, tempered for average hardness of 346 HB.
50
VIEW
ML00158 / Feb.2020
Surface Hardened Carbon Steel Wheel
M - High Carbon SteelP - WheelAp - TransportationCd - Removed From Service
Cm - Nital Etched Micrography by OMDf - At the Surface
ML00081 — Hydrogen Cracking of a Chromium Plated Carburized PinM - Low Alloy for Thermochemical TreatmentP - Chromium PlatedAp - AutomotiveCd - Hydrogen Embrittlement
Scanning electron fractography showing that the fracture micromechanism is intergranular close to the surface of the pin, suggesting a hydrogen embrittlement effect at the carburized layer. The cracks were created during the electrolytic plating, and propagated later during service.
45
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 - At the Surface