In-situ acoustic emission (AE) and Raman measurements, focusing on the adhesion of a protective oxide scale, were conducted to clarify the breakaway behavior under cyclic condition. The AE measurement showed that the scale failure such as spalling and/or cracking occurred even after one cycle of 3 hr heating at 1173 °K. It was also clarified that the scale stress without the creep-deformation and spalling corresponded to calculated thermal stress. The critical adhesion force of the scale on 25Cr-20Ni steel heated for 3 hr at 1173 °K was estimated to be 1.7± 0.2 GPa in the range of 573 °K (-ΔT =600 °K) to the room temperature. Cyclic heating accelerated the spalling of the oxide scale, resulting in gradual degradation of protective oxide scale. These processes have induced breakaway oxidation of austenitic stainless steel.

Subject
Foil, Materials, Stress relaxation, Thermal stress, Stress, Oxide scales, Mechanical failure, Metals, Steel, Scale, Spalling, Adhesion, Oxidation
Keywords:
Cr2O3, mechanical stress, in-situ measurement Raman spectroscopy, acoustic emission
© 2007 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).
2007
Association for Materials Protection and Performance (AMPP)
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