Investigation of Nonmetallic Inclusions and their Corellation to Pitting Corrosion of Austenitic Stainless Steels

Bibliographic Details
Main Author:	Kashfipour, Marjan Alsadat
Language:	English
Published:	University of Akron / OhioLINK 2015
Subjects:	Chemical Engineering
Online Access:	http://rave.ohiolink.edu/etdc/view?acc_num=akron1447689604

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spelling	ndltd-OhioLink-oai-etd.ohiolink.edu-akron14476896042021-08-03T06:33:55Z Investigation of Nonmetallic Inclusions and their Corellation to Pitting Corrosion of Austenitic Stainless Steels Kashfipour, Marjan Alsadat Chemical Engineering Although the effect of non-metallic inclusions on pitting corrosion of stainless steel alloys have been an interesting topic during last decades, the role of the inclusions on pitting initiation and propagation is still under discussion. In this study, different types of inclusions consisting of carbon, nitrogen, silicon, oxygen, manganese, Sulfur etc. on 304L and 303 stainless steels have been investigated using Atomic Force Microscopy (AFM), Scanning Electron Microscopy (SEM), Energy Dispersive X-ray spectroscopy (EDX) and Focused Ion Beam (FIB) techniques. Preliminary in-situ AFM results in 0.1 M NaCl indicate the deposition of copper on MnS inclusions at anodic potentials but not at the Open Circuit Potential (OCP). No pitting was observed at MnS inclusions or the adjacent area. Pit propagation at the MnS-matrix boundaries was observed in-situ while it was exposed to 0.1 M NaCl solution. In these experiments samples were pretreated by exposure to acidic chloride solution at the OCP. Although it was initially appeared to be pit initiation, it was demonstrated later via SEM-FIB analysis that the observed trenches on the surface were in fact the propagated pits below the surface which reached to the top at some point. Based on SEM-FIB cross-section observation, the MnS inclusions were passivated by a thin layer of copper, presumably as Cu2S. Further examination of other types of inclusions, showed that there was no pitting corrosion at the inclusion-matrix boundaries. This indicates that local chemistry and not the geometry is the more probable reason for the MnS-matrix boundaries to be corroded. 2015 English text University of Akron / OhioLINK http://rave.ohiolink.edu/etdc/view?acc_num=akron1447689604 http://rave.ohiolink.edu/etdc/view?acc_num=akron1447689604 unrestricted This thesis or dissertation is protected by copyright: all rights reserved. It may not be copied or redistributed beyond the terms of applicable copyright laws.
collection	NDLTD
language	English
sources	NDLTD
topic	Chemical Engineering
spellingShingle	Chemical Engineering Kashfipour, Marjan Alsadat Investigation of Nonmetallic Inclusions and their Corellation to Pitting Corrosion of Austenitic Stainless Steels
author	Kashfipour, Marjan Alsadat
author_facet	Kashfipour, Marjan Alsadat
author_sort	Kashfipour, Marjan Alsadat
title	Investigation of Nonmetallic Inclusions and their Corellation to Pitting Corrosion of Austenitic Stainless Steels
title_short	Investigation of Nonmetallic Inclusions and their Corellation to Pitting Corrosion of Austenitic Stainless Steels
title_full	Investigation of Nonmetallic Inclusions and their Corellation to Pitting Corrosion of Austenitic Stainless Steels
title_fullStr	Investigation of Nonmetallic Inclusions and their Corellation to Pitting Corrosion of Austenitic Stainless Steels
title_full_unstemmed	Investigation of Nonmetallic Inclusions and their Corellation to Pitting Corrosion of Austenitic Stainless Steels
title_sort	investigation of nonmetallic inclusions and their corellation to pitting corrosion of austenitic stainless steels
publisher	University of Akron / OhioLINK
publishDate	2015
url	http://rave.ohiolink.edu/etdc/view?acc_num=akron1447689604
work_keys_str_mv	AT kashfipourmarjanalsadat investigationofnonmetallicinclusionsandtheircorellationtopittingcorrosionofausteniticstainlesssteels
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Investigation of Nonmetallic Inclusions and their Corellation to Pitting Corrosion of Austenitic Stainless Steels

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