Slow strain rate testing is being used not only as a rapid method for ranking alloys for material selection purposes for downhole use, but also as a quality control test method. However, it is subject to great variability in test results and further evaluation of the test method is required before it can be successfully used as a quality control test method. The effects of surface finish, strain rate, and electrode potential are some of the parameters that should be considered in interpretation of SSRT data. For example, variances in specimen surface preparation can lead to erroneous results and conclusions. Nickel-base SSRT specimens must be prepared by machining and polishing techniques that avoid creating stress concentrators and high tensile residual stresses. Ensuring a surface finish of 10 μin (0.25 μm) or less and specimen preparation using low stress grinding techniques is one way of eliminating errors due to surface effects. Further, the only reliable and acceptable methods of confirming SCC is by metallographic or fractographic examination. Once confirmation is obtained by either of these techniques, then reduction in area ratios can be used to quantify the susceptibility.

Subject
Test methods, Strain rate, Sour environments, C ring stress corrosion testing, Mechanical failure, Test environments, Specimen preparation, Risk reduction, Alloys, Stress corrosion cracking, Residual stress, Slow strain rate technique, Electrode potential
Keywords:
slow strain rate testing, quality assurance, oil and gas, stress corrosion cracking, nickel-base, corrosion resistant alloys, surface preparation, strain rate, electrode potential
© 1993 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).
1993
Association for Materials Protection and Performance (AMPP)
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