Polythionic Acid Stress Corrosion Cracking (PTA SCC) of conventional austenitic stainless steel is a serious problem in refinery desulfurization units. Stabilization treatment after welding, Nitrogen blanketing and/or neutralization treatment using an alkaline solution are required during each turn around to prevent PTA SCC according to NACE(1) SP0170-2012.

It has been known that proprietary S34751 has superior PTA SCC resistance compared with S34700 or S32100 even without Post Weld Heat Treatment (PWHT) and neutralization treatment during turn around. However, the difference of of PTA SCC resistance between proprietary S34751 and generic S34751 within extra low Carbon (C) content less than 0.02 wt% has not been reported.

Therefore, the relationship between C content and PTA SCC resistance for generic S34751 was investigated by using long term aged samples with simulated welding Heat Affected Zone.

Subject
Grain size, Materials, Intergranular stress corrosion cracking, Precipitation (solids), Microstructure, Nucleation, Force, Sensitization, Carbon, Caustic stress corrosion cracking, Grain boundary, Stress corrosion cracking, Aging
Keywords:
Polythionic acid stress corrosion cracking (PTA SCC), Sensitization, Proprietary version S34751, Hydroprocessing, Carbon content
© 2019 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).
2019
Association for Materials Protection and Performance (AMPP)
You do not currently have access to this content.