Fine Transgranular Precipitation

2 cases · 6 images

Crevice Corrosion in a Subsea System — Aspect Before Analysis

Capture method: Optical Microscope Detail focus: Microstructure clear all

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Micrography of the 1.65 mm thickness tube, in the middle of the thickness of the longitudinal section. This part of the tube is located in the colder part of the equipment, position 1. The material presented carbide precipitation at grain boundaries (not yet fully surrounding the grains) and at this point the tube presented no internal corrosion.
338
VIEW
ML00086 / Nov.2017
Intergranular Corrosion of Sensitized 304SS
M - Austenitic Stainless SteelP - Seamless tubeAp - Heat ExchangerCd - Intergranular Corrosion
Cm - Micrography by OM using A262 Method ADf - Austenite
Transverse section of the blade showing large grains of this poliycristaline cast material.
421
VIEW
ML00042 / Apr.2017
Gas Turbine Blade IN 939, Coated
M - NiCrCo AlloyP - CastAp - Gas TurbineCd - Intergranular Cracking
Cm - H2SO4+HNO3+H3PO4 Etched MicroDf - Coarse Structure

More from these cases

ML00086 — Intergranular Corrosion of Sensitized 304SSM - Austenitic Stainless SteelP - Seamless tubeAp - Heat ExchangerCd - Intergranular Corrosion
Micrography of the 1.65 mm thickness tube, in the middle of the thickness of the longitudinal section. This part of the tube is located in position 2, where the temperature was higher and the carbide precipitation increased during service.
272
VIEW
ML00086 / Nov.2017
Intergranular Corrosion of Sensitized 304SS
M - Austenitic Stainless SteelP - Seamless tubeAp - Heat ExchangerCd - Intergranular Corrosion
Cm - Micrography by OM using A262 Method ADf - Intergranular Precipitation
Micrography of the 1.65 mm thickness tube, in the middle of the thickness of the longitudinal section. This part of the tube is located in position 3, where intergranular and transgranular carbide precipitation occurred during service.
234
VIEW
ML00086 / Nov.2017
Intergranular Corrosion of Sensitized 304SS
M - Austenitic Stainless SteelP - Seamless tubeAp - Heat ExchangerCd - Intergranular Corrosion
Cm - Micrography by OM using A262 Method ADf - Intragranular Secondary Precipitation
Micrography of a longitudinal section of the tube in position 3, at the internal surface. Although there is a strong precipitation, both intergranular and transgranular, the tube did not corrode at this point.
144
VIEW
ML00086 / Nov.2017
Intergranular Corrosion of Sensitized 304SS
M - Austenitic Stainless SteelP - Seamless tubeAp - Heat ExchangerCd - Intergranular Corrosion
Cm - Micrography by OM using A262 Method ADf - Intragranular Secondary Precipitation
Micrographic detail of the internal side of the tube in position 3, with a strong intergranular and transgranular precipitation, but no corrosion at this point.
153
VIEW
ML00086 / Nov.2017
Intergranular Corrosion of Sensitized 304SS
M - Austenitic Stainless SteelP - Seamless tubeAp - Heat ExchangerCd - Intergranular Corrosion
Cm - Micrography by OM using A262 Method ADf - Intragranular Secondary Precipitation