The aim of this paper is to study the effect of chlorides in diluted sulfuric acid upon the uniform corrosion resistance of a nitrogen containing duplex stainless steel grade UNS S32550 (alloy 255).

Base metal and TIG welds were tested in various chloride and sulfuric acid mixtures at 70°C.

The corrosion behavior of two austenitic grades (UNS S31603 and UNS N08904) was compared to the duplex one.

The superiority of the α/γ structure is evidenced in several mixtures where the austenitic grades suffer uniform corrosion.

Nevertheless, in mixtures containing high sulfuric acid and chloride contents, a selective corrosion of the ferrite phase can occur. Such a phenomenon was studied by potentiokinetic polarization tests and microstructure examinations.

We proposed an isocorrosion diagram in order to underline mixtures in which the duplex alloy 255 (welds and base metal) can be used safely.

Subject
Corrosion resistant alloys, Stainless alloys, Corrosion rate, Microstructure, Sulfuric acid, Sodium chloride, Mixtures, Base metals, Sodium chloride solution, Corrosion resistance, Ferrite, Alloys, Chlorides
© 1991 Association for Materials Protection and Performance (AMPP). All rights reserved. No part of this publication may be reproduced, stored in a retrieval system, or transmitted, in any form or by any means (electronic, mechanical, photocopying, recording, or otherwise) without the prior written permission of AMPP. Positions and opinions advanced in this work are those of the author(s) and not necessarily those of AMPP. Responsibility for the content of the work lies solely with the author(s).
1991
Association for Materials Protection and Performance (AMPP)
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