The carburization resistance of two emerging alloys for ethylene pyrolysis service was investigated and compared with that of two existing alloys. One of the emerging alloys, alloy U, contained about 40% chromium and 50% nickel by weight and was similar to existing alloys in terms of microstructure and strengthening mechanisms. The other emerging alloy, known as ExoAlloy1, was based on the Ni3Al nickel aluminide system. Nickel aluminides have outstanding creep rupture strengths compared to other cast alloys. Their carburization resistance, however, has not yet been compared to standard alloys in a manner that is consistent with standard industrial test methods. In this paper a comparison is made of the carburization resistance of the two emerging and two existing materials. In addition, a brief analysis of the expected furnace life was made, based on both the strength and carburization resistance of the four materials. It was found that one emerging material, alloy U, would provide an exceptional increase in either the furnace life or the operating temperature of the furnace coil. The nickel aluminide alloy would also be expected to provide increased furnace coil life, but does not allow a large increase in furnace operating temperature.

Subject
Carburization, Materials, Metal surfaces, Nickel based alloys, Tubes, Walls, Stress, Furnaces, Aluminides, Creep, Carbon, Nickel, Aluminum alloys
Keywords:
heat resistant, carburization, ethylene, pyrolysis, cracking, nickel aluminide, Ni3Al
© 1999 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).
1999
Association for Materials Protection and Performance (AMPP)
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