It had been proposed that centrifugally cast stainless steel pipe be used in hydroformer and hydrotreater applications in place of wrought pipe to take advantage of the lower cost of cast stainless steel. An investigation was conducted to determine if the properties of these steels would degrade after continuous exposure to temperatures in the range 750°F to 950°F (400°C to 510°C). It was determined that the toughness of duplex (austenite-ferrite) centrifugally cast pipe degraded with time while the toughness of wrought Type 321 stainless steel was unaffected by exposures up to 5000 hours. The degradation of properties observed in these steels after aging was attributed to the formation of precipitates in the ferrite portion of the microstructure including: chromium carbides, alpha prime, and "G" phase. This work may also have relevance to the degradation of stainless steel welds after long-term exposure to temperatures in the 575°F-950°F (300°C-510°C) range.

Subject
Embrittlement, Carbides, Stainless alloys, Microstructure, Charpy impact test, Steel, Stainless steel, Ferrite, Alloys, Toughness, Wrought metals, Aging, Austenite
© 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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