Damage

1 case · 6 images

Crevice Corrosion in a Subsea System — Aspect Before Analysis

Condition: Scaling Microstructure: Austenite clear all

Damage — sub-branches

Intergranular Cracking 1Intergranular Fracture 2Oxide Layer 1Thinning 2

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Transverse section macrography of the plate where the degradation by thinning is worst, close to the original corners of the tube. The thinning is occurrring from the product reaction side (side A to the bottom of the figure). The macrography shows a reduction in the thickness from 2 mm (right side, sample 2) to almost zero (left side, sample 1).
86
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ML00160 / Apr.2020
High Temperature Degradation of 310SS
M - Austenitic Stainless SteelP - Rectangular TubeAp - Chemical IndustryCd - Scaling
Cm - Transverse Section AspectDf - Thinning

More from these cases

ML00160 — High Temperature Degradation of 310SSM - Austenitic Stainless SteelP - Rectangular TubeAp - Chemical IndustryCd - Scaling
Longitudinal section macrography of the plate where the degradation by thinning is reducing the thickness from 6mm to 4mm (sample 3). The thinning is occurrring from the product reaction side (side A to the bottom of the figure).
83
VIEW
ML00160 / Apr.2020
High Temperature Degradation of 310SS
M - Austenitic Stainless SteelP - Rectangular TubeAp - Chemical IndustryCd - Scaling
Cm - Longitudinal Section AspectDf - Thinning
SAMPLE 1 AT THE FRACTURE - Micrographic detail of the intergranular fracture. The austenitic grains of the material are loosing.
80
VIEW
ML00160 / Apr.2020
High Temperature Degradation of 310SS
M - Austenitic Stainless SteelP - Rectangular TubeAp - Chemical IndustryCd - Scaling
Cm - Oxalic Acid Electrolytic EtchDf - Intergranular Fracture
SAMPLE 1, AT THE FRACTURE - Micrography, as polished, of the oxides at the fracture (zero thickness). In this region the oxide layer penetrated through thickness, intergranular, and fractured the material.
63
VIEW
ML00160 / Apr.2020
High Temperature Degradation of 310SS
M - Austenitic Stainless SteelP - Rectangular TubeAp - Chemical IndustryCd - Scaling
Cm - As polished micrographyDf - Intergranular Fracture
SAMPLE 1, AT THE FRACTURE - Micrographic detail, as polished, of the oxides that are penetrating in the austenitic grain boundaries. The oxidation created intergranular cracks in regions close to the edge of the rectangular tube, that are more susceptible to suffer cyclic thermal stresses, since the furnace is weekly turned off, during two days.
55
VIEW
ML00160 / Apr.2020
High Temperature Degradation of 310SS
M - Austenitic Stainless SteelP - Rectangular TubeAp - Chemical IndustryCd - Scaling
Cm - As polished micrographyDf - Intergranular Cracking
SAMPLE 1 AT THE FRACTURE - Micrographic detail by scanning electron microscopy, as polished, of the oxides that are penetrating in the grain boundaries. The EDS showed high Molibdenium content in the penetrating oxides. The process uses Mo oxides to make metallic Mo and the high Mo content at the surface could be responsible for reducing the oxidation resistance of the material and intensifying the thinning at the process side (side A).
48
VIEW
ML00160 / Apr.2020
High Temperature Degradation of 310SS
M - Austenitic Stainless SteelP - Rectangular TubeAp - Chemical IndustryCd - Scaling
Cm - Micrography by SEMDf - Oxide Layer