Process industries, including pulp, paper and biomass conversion are constantly in search of new, cost-efficient materials solutions. Duplex stainless steels are attractive in this respect by virtue of their combination of high strength, price stability, and corrosion resistance compared to their austenitic counterparts. The range of duplex grades extends from the lean low-Mo grades and up to high-performance super- or hyperduplex. The new duplex grade S82441 has a property profile designed to fill the gap between the existing duplex grades S32304 and S32205. In this paper the property profile of the new duplex steel UNS S82441, (24Cr,3.6Ni,1.6Mo,3Mn) is mainly compared to 316L and S32205.

This paper describes the results of localized corrosion testing according to ASTM G 48 (pitting and crevice corrosion in ferric chloride), ASTM G 150 (electrochemical testing in NaCl), ASTM G 36 (stress corrosion cracking in MgCl2) and ASTM G 123 (stress corrosion cracking in NaCl) for a variety of product forms. Corrosion in acidic and alkaline media is illustrated with corrosion rates and the critical temperature, evaluated according to the MTI-1 (ASTM G 157) method as the lowest temperature at which the extrapolated corrosion rate exceeds a 0.127 mm/year (5 mpy).

Potential application areas for the new grade are foreseen within pulp & paper processing, in which there are advantages to be gained from the higher strength of the grade and its superior corrosion resistance in caustic environments such as white liquor.

Subject
Test methods, Materials, Critical temperature, Corrosion rate, Pulp, Sulfuric acid, Sodium chloride, Pitting, Sodium hydroxide, Environments, Corrosion resistance, Localized corrosion, Chloride stress corrosion cracking
Keywords:
stainless steel, duplex, pulp & paper, sodium hydroxide
© 2012 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).
2012
Association for Materials Protection and Performance (AMPP)
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