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ML00054 - Dec.2018donated by: Noah Nahas

Cutlery Corrosion

Tempered martensitic microstructure of the knife observed in a transverse section micrography. There are also secondary carbides (white globules) that increase the material wear resistance.

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Tempered martensitic of the knife observed in a . There are also (white globules) that increase the material resistance.
M

Material

Martensitic Stainless Steel
  • UNS S42000
  • AISI 420
Ds

Description

A full set of flatware has been stored in a drawer after a barbecue. Three months later the knives from the bottom of the drawer appeared in a rusted condition, probably because they were not properly cleaned and dried. The metallurgical analysis indicated that the material presented a and the analysis inside the pitting indicated a high Cl peak, which means that the cooking salt was not properly removed from the surface before storing.

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Chemistry (% in weight)

Product analysis

0.22C; 0.39Si; 0.36Mn; 0.025P; 0.011S; 13.7Cr; 0.12Ni; 0.07Cu.

Associated Images
Aspect of the rusted knife, before cleaning.
1195
VIEW
ML00054 / Dec.2018
Cutlery Corrosion
M - Martensitic Stainless SteelP - Foodstuff ArticleAp - KitchenCd - Pitting Corrosion
Cm - Aspect Before AnalysisDf - Corrosion
Detail of the rusted surface of the knife, before cleaning.
340
VIEW
ML00054 / Dec.2018
Cutlery Corrosion
M - Martensitic Stainless SteelP - Foodstuff ArticleAp - KitchenCd - Pitting Corrosion
Cm - Surface AspectDf - Corrosion
Tempered martensitic microstructure of the knife observed in a transverse section micrography. There are also secondary carbides (white globules) that increase the material wear resistance.
254
VIEW
ML00054 / Dec.2018
Cutlery Corrosion
M - Martensitic Stainless SteelP - Foodstuff ArticleAp - KitchenCd - Pitting Corrosion
Cm - Kalling Etched Micrography by SEMDf - Martensite
Detail of the tempered martensitic microstructure with secondary carbides of the knife, observed in a transverse section micrography.
206
VIEW
ML00054 / Dec.2018
Cutlery Corrosion
M - Martensitic Stainless SteelP - Foodstuff ArticleAp - KitchenCd - Pitting Corrosion
Cm - Kalling Etched Micrography by SEMDf - Martensite
Aspect of the rusted surface after cleaning, showing adhered products at the surface, in regions where the passive layer was destroyed and pitting corrosion occurred.
184
VIEW
ML00054 / Dec.2018
Cutlery Corrosion
M - Martensitic Stainless SteelP - Foodstuff ArticleAp - KitchenCd - Pitting Corrosion
Cm - Surface Aspect by SEMDf - Corrosion
Detail of the rusted surface. EDS analysis inside the pitting shows a high Cl peak (the bright aspect inside the pitting), indicating that the salt over the surface was responsible for destroying the passive layer and the localized corrosion occurred.
172
VIEW
ML00054 / Dec.2018
Cutlery Corrosion
M - Martensitic Stainless SteelP - Foodstuff ArticleAp - KitchenCd - Pitting Corrosion
Cm - Surface Aspect by SEMDf - Corrosion
Micrographic aspect of the pitting corrosion at the knife surface. It is possible to see the typical pitting aspect of a localized corrosion that appears as a small dot at the surface but it is a big crater under the surface.
185
VIEW
ML00054 / Dec.2018
Cutlery Corrosion
M - Martensitic Stainless SteelP - Foodstuff ArticleAp - KitchenCd - Pitting Corrosion
Cm - Micrography by SEMDf - Pitting
Detail of the micrographic aspect of the pitting corrosion at the knife surface.
168
VIEW
ML00054 / Dec.2018
Cutlery Corrosion
M - Martensitic Stainless SteelP - Foodstuff ArticleAp - KitchenCd - Pitting Corrosion
Cm - Micrography by SEMDf - Pitting
Micrographic aspect of the corrosion damage in a section transverse to the pitting.
167
VIEW
ML00054 / Dec.2018
Cutlery Corrosion
M - Martensitic Stainless SteelP - Foodstuff ArticleAp - KitchenCd - Pitting Corrosion
Cm - Kalling Etched Micrography by OMDf - Pitting