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ML00015 - Oct.2017

Intergranular Corrosion of 304SS Plate

Detail of the fusion line region of the repair weld. It is possible to see that the cracks are filled with oxides indicating that the material was already corroded when the bead was deposited.

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Detail of the region of the . It is possible to see that the are filled with oxides indicating that the material was already corroded when the bead was deposited.
M

Material

Austenitic Stainless Steel
  • UNS S30400
  • ASTM A 240 TP 304
Ds

Description

The duct was operating at 485°C and after several years in service the material presented local and a repair was conducted. During repair, several appear adjacent to the weld. The metallurgical investigation indicated that the plate has been sensitized during service and suffered in several locations along the surface. The stresses imposed by the repair welding in these embrittled regions (with intergranular corrosion) opened the cracks.

C

Chemistry (% in weight)

Product Analysis

0.05C; 0.50Si; 1.75Mn; 0.027P; 0.007S; 18.03Cr; 8.19Ni; 0.25Mo; 0.36Cu.

Associated Images
The micrography of the transverse section of the plate, as polished, close to the surface. The material presents intergranular corrosion and some grains were lost.
1184
VIEW
ML00015 / Oct.2017
Intergranular Corrosion of 304SS Plate
M - Austenitic Stainless SteelP - Rolled PlateAp - RefineryCd - Intergranular Corrosion
Cm - Micrography by OMDf - Intergranular Corrosion
Microstructure of the plate in the center of the ¼” thickness. Equiaxed austenitic grains with delta ferrite stringers and grain boundary carbide precipitation (sensitization).
303
VIEW
ML00015 / Oct.2017
Intergranular Corrosion of 304SS Plate
M - Austenitic Stainless SteelP - Rolled PlateAp - RefineryCd - Intergranular Corrosion
Cm - Micrography by OM using A262 Method ADf - Intergranular Precipitation
Microstructure of the plate in the center of the ¼” thickness. Equiaxed austenitic grains with delta ferrite stringers and grain boundary carbide precipitation (sensitization).
201
VIEW
ML00015 / Oct.2017
Intergranular Corrosion of 304SS Plate
M - Austenitic Stainless SteelP - Rolled PlateAp - RefineryCd - Intergranular Corrosion
Cm - Micrography by OM using A262 Method ADf - Intergranular Precipitation
Micrographic aspect of a longitudinal section of the plate, close to the surface, in a region where it was detected intergranular corrosion up to 0,5 mm depth. As polished.
188
VIEW
ML00015 / Oct.2017
Intergranular Corrosion of 304SS Plate
M - Austenitic Stainless SteelP - Rolled PlateAp - RefineryCd - Intergranular Corrosion
Cm - Micrography by OMDf - Intergranular Corrosion
Micrographic detail of intergranular corrosion, up to 0,5 mm depth. As polished.
171
VIEW
ML00015 / Oct.2017
Intergranular Corrosion of 304SS Plate
M - Austenitic Stainless SteelP - Rolled PlateAp - RefineryCd - Intergranular Corrosion
Cm - Micrography by OMDf - Intergranular Corrosion
Micrographic aspect of a longitudinal section of the plate, close to the surface, in a region with intergranular corrosion. Several loose grains were removed, indicating that the structure was embrittled by the intergranular corrosion.
171
VIEW
ML00015 / Oct.2017
Intergranular Corrosion of 304SS Plate
M - Austenitic Stainless SteelP - Rolled PlateAp - RefineryCd - Intergranular Corrosion
Cm - Micrography by OM using A262 Method ADf - Intergranular Corrosion
Visual aspect of the repair welded plate surface, cracked during welding. Several cracks paralell to the welded regions, revealed by dye check, appear adjacent to the repair beads. The width of the repair is 15 mm.
153
VIEW
ML00015 / Oct.2017
Intergranular Corrosion of 304SS Plate
M - Austenitic Stainless SteelP - Rolled PlateAp - RefineryCd - Intergranular Corrosion
Cm - Aspect by NDTDf - At the Surface
Micrography of a section transverse to the repair weld showing that the macroscopic crack, detected at the surface of the plate, occurred exactly at the margin of the weld bead. It is possible to see that the bead was deposited over a region that was already corroded (intergranular corrosion) and the macroscopic crack is the opening of several corroded grains.
158
VIEW
ML00015 / Oct.2017
Intergranular Corrosion of 304SS Plate
M - Austenitic Stainless SteelP - Rolled PlateAp - RefineryCd - Intergranular Corrosion
Cm - Micrography by OM using A262 Method ADf - Intergranular Cracking
Detail of the fusion line region of the repair weld. It is possible to see that the cracks are filled with oxides indicating that the material was already corroded when the bead was deposited.
128
VIEW
ML00015 / Oct.2017
Intergranular Corrosion of 304SS Plate
M - Austenitic Stainless SteelP - Rolled PlateAp - RefineryCd - Intergranular Corrosion
Cm - Micrography by OM using A262 Method ADf - Intergranular Cracking
Detail of the fusion line region of the repair weld. It is possible to see that the cracks are filled with oxides indicating that the material was already corroded when the bead was deposited.
108
VIEW
ML00015 / Oct.2017
Intergranular Corrosion of 304SS Plate
M - Austenitic Stainless SteelP - Rolled PlateAp - RefineryCd - Intergranular Corrosion
Cm - Micrography by OM using A262 Method ADf - Intergranular Cracking
Detail of the fusion line region of the repair weld. Cracks filled with oxides indicating that the material was already corroded when the bead was deposited.
105
VIEW
ML00015 / Oct.2017
Intergranular Corrosion of 304SS Plate
M - Austenitic Stainless SteelP - Rolled PlateAp - RefineryCd - Intergranular Corrosion
Cm - Micrography by OM using A262 Method ADf - Crack