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Crystallographic effects in corrosion of austenitic stainless steel 316L
Swerea Kimab AB, Sweden.
Jernkontoret, Sweden.
2014 (English)Article in journal (Refereed) Epub ahead of print
Abstract [en]

Electron backscatter diffraction and confocal laser microscopy have been used to quantify the degree of crystallographic anisotropy during corrosion of AISI 316L in two test solutions. Corrosion in 30 vol% H2SO4 sulphuric acid shows pronounced crystallographic anisotropy in which the corrosion rate increases in the order {111} < {110} ≲ {100}. The ratio between the slowest corroding {111} and the fasting corroding {100} surfaces is about 3. Pitting corrosion in a solution of FeCl3 and AlCl3 in ethanol/glycerol agrees with other reported observations that high-atomic density surfaces {111} and {100} are less prone to pit nucleation, however the effect was relative small.

Place, publisher, year, edition, pages
Keyword [en]
anisotropy, corrosion, sulphuric acid, pitting
National Category
Metallurgy and Metallic Materials
URN: urn:nbn:se:kth:diva-159025DOI: 10.1002/maco.201408002OAI: diva2:782234

QC 20150120

Available from: 2015-01-20 Created: 2015-01-20 Last updated: 2015-01-21Bibliographically approved
In thesis
1. Process-microstructure-corrosion interrelations for stainless steel
Open this publication in new window or tab >>Process-microstructure-corrosion interrelations for stainless steel
2015 (English)Doctoral thesis, comprehensive summary (Other academic)
Abstract [en]

Stainless steels were first developed in the early 20th century and have since then emerged as a very diverse class of engineering materials. Along with steels having new combinations of properties, there is a continuous development of new technologies allowing the material to be produced in a faster and more energy effcient manner. A prerequisite for new technologies to be adapted quicklyis a fundamental understanding of the microstructure evolution throughout theprocess chain. The first part of this thesis has been dedicated to the annealing and pickling processes from a process-microstructure perspective. In the second part the concept of utilising crystallographic texture as a way to attain microstructures with new combinations of properties has been evaluated.

In the first part, annealing can be regarded as a high temperature oxidation process, resulting in chromium depletion that necessitate subsequent chemical pickling. Chemical pickling, on the other hand, is basically a wet-corrosion process and hence more difficult for highly corrosion-resistant grades. The chromium depleted layer was found to be enriched in austenite in case of duplex stainless steel UNS S32205 (Paper I) and this may inuence the pickling process. Proper pretreatment like shot-blasting dramatically increases the pickling rate because it provides the pickling acid with access to the chromium depleted layer (Paper II). Oxidation kinetics for S30400 in conditions relevant to strip annealing do not seem to be affected by the choice of air/oxygen as oxidiser even though the latter results in substantially higher water content (Paper III). This gives new possibilities regarding both cost savings and increased throughput.

In the second part, the effect of crystallographic texture on resistance towards corrosion of S31603 in a solution of FeCl3 and AlCl3 in ethanol/glycerol and in 30 vol% H2SO4 is investigated. In the former, high density surfaces {1111} and {100} are less prone for pit nucleation, however the effect is relativelysmall. In H2SO4 pronounced crystallographic anisotropy is observed inwhich the corrosion rate increase in the order {111} < {110} ≤ {100} (Paper IV).For corrosion at high temperatures, chromium diffusion is governed by randomhigh angle boundaries with ~20—55° misorientation. The possibilities to alter the texture in austenitic stainless steels by means of warm-rolling and annealing has been evaluated for S30403 and S31603. During warm-rolling, both steels develop the copper-type texture in contrast to the brass-type texture observedat room temperature. However only S30403 is prone to recrytallise cube texture during subsequent annealing (Paper V).

Place, publisher, year, edition, pages
Stockholm: KTH Royal Institute of Technology, 2015. xii, 75 p.
TRITA-CHE-Report, ISSN 1654-1081 ; 2015:3
stainless steel, processing, annealing, pickling, microstructure, corrosion, anisotropy, oxyfuel
National Category
Metallurgy and Metallic Materials
Research subject
urn:nbn:se:kth:diva-159072 (URN)978-91-7595-425-7 (ISBN)
Public defence
2015-02-16, F3, Lindstedtsvägen 26, KTH, Stockholm, 10:00 (English)

QC 20150121

Available from: 2015-01-21 Created: 2015-01-20 Last updated: 2015-01-21Bibliographically approved

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Lindell, DavidPettersson, Rachel
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