Mechanical properties up to 400°C and microstructural evolution of Duplex 22 and 25% Cr stainless steel tubing have been determined as a function of the amount of cold working. The following nominal mechanical grades (ksi) were considered: 75 for extruded and quenched (EQ) tubing; 110 and 125, obtained by cold drawing up to 10 and 20% of reduction of area (RA) respectively; 140, obtained by means of cold pilgering at RA of 50%.

Susceptibility to SSCC has been determined in an acidified (pH ≃ 2.7) sour environment in the temperature range 22-140°C through engineering diagrams based on the pass-fail criterion. Thus, the critical NaCl concentration and pH2S have been determined as a function of cold working for qualification and selection of duplex steel tubing most suitable for use in a given environment. Cold worked tubing maintains the corrosion performance of EQ tubing up to grade 125 for D25 and grade 110 for D22. A marked reduction in SSCC resistance has been observed for D22-125 and for both D22-140 and D25-140.

Subject
Stability, Materials, Tubes, Sodium chloride, Partial pressures, Acidity, Mechanical properties, Tubing, Salt concentration, Steel, Corrosion resistance, Risk reduction, Cold working
© 1987 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).
1987
Association for Materials Protection and Performance (AMPP)
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