In order to improve the durability and cost performance of weld overlay superheater tubes used in high efficiency waste-to-energy boilers, a reverse polarity plasma arc welding process was developed. Evaluation of the high-temperature corrosion-resistance was carried out by using a thermal gradient corrosion test method and by a 4000 hour field corrosion test in a high-efficiency waste-to-energy boiler supplying 500°C/9.8MPa steam. From these evaluations, good corrosion-resistance which is equal to conventional weld overlay processes, or more, was confirmed. Especially with a newly developed process, localized corrosion arising in the bonding part of SA178/weld metal and selective corrosion of the weld metal were less than conventional welding processes due to it’s lower dilution and heat input.

Subject
Materials, Corrosion resistant alloys, Tubes, Welding, Corrosion testing, Polarity, Plasma, Thickness loss, Gas metal arc welding, Metals, Boilers, Alloys, Durability
Keywords:
weld overlay, waste-to-energy plant, superheater tube, alloy 625, alloy 310, corrosion-resistant materials, reverse polarity plasma arc welding, thermal gradient corrosion test, field corrosion test, locarized corrosion
© 2002 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).
2002
Association for Materials Protection and Performance (AMPP)
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