The localized corrosion resistance of stainless steels and nickel alloys is primarily due to alloying elements. The most important elements, as indicated by the Pitting Resistance Equivalent (PRE) are Cr, Mo, N and sometimes W. This paper compares the effect of these elements in pitting and crevice corrosion. Using ASTM G48 Methods C and D, the critical pitting temperature and critical crevice temperature are determined for several superaustenitic stainless steels (UNS N08366, N08367, N08830 and N08031) and a nickel alloy (UNS N06625). The varying effect of the elements on the two forms of corrosion and its relation to localized corrosion mechanisms are discussed. Differences between pitting corrosion and crevice corrosion are discussed. Most notably, the CCT of N06625 was the same as that of N08367 (6Mo) although the CPT of N06625 was at least 25 °C greater than that of N08367 (6Mo).

Subject
Corrosion resistant alloys, Stainless alloys, Nickel based alloys, Molybdenum alloys, Superaustenitic stainless steel, Alloying elements, Crevice corrosion, Pitting, Corrosion resistance, Localized corrosion, Stainless steel, Elements, Alloys
Keywords:
PRE, ASTM G48, stainless steels, nickel alloys, pitting corrosion, crevice corrosion, localized corrosion
© 2017 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).
2017
Association for Materials Protection and Performance (AMPP)
You do not currently have access to this content.