Effect of strain rate and applied potential on SCC susceptibility by SSRT was investigated in sour and S-containing sour environments. Long term C-ring tests were also carried out in these environments and their test results were compared with SSRT results. The susceptibility in SSRT was observed to be highest around the strain rate of 4 to 10 X 10-6 s-1 and decreased on the slower strain rate of 4 X 10-7 s-1. Further, its susceptibility strongly depended on the applied potential and therefore was affected by the insulation between the specimen and the specimen holder, and the oxidant such as elemental S. The S addition more than 1g/l, which is estimated to exceed the solubility of elemental S in S-H2O system and deposit on the specimen surface, was indicated to increase the corrosion rate and accelerate SCC. The C-ring test results gave the same good relationship between the critical temperature for SCC resistance and the Mo content in materials as the SSRT results. Therefore, SSRT is useful method on SCC evaluation in a short time from this relationship.

Subject
Noble potential, Strain rate, Materials, Insulation, Corrosion resistant alloys, Sour environments, C ring stress corrosion testing, Environments, Corrosion resistance, Alloys, Corrosion potential, Stress corrosion cracking, Electrode potential
Keywords:
stress corrosion cracking(SCC), corrosion resistant alloy(CRA), hydrogen sulfide, elemental sulfur, slow strain rate test(SSRT), constant strain test, C-ring test, evaluation method, Ni base alloy
© 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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