A finite difference hydrogen induced crack (HIC) growth model has been developed, enabling for the first time an accurate simulation of the growth of HIC cracks in the wall of pipelines and/or pressure vessels. In the model, parameters such as defect size, location, fracture toughness and hydrogen concentration, can be varied. The predictions of the HIC model are compared with experimental HIC crack growth curves, which were generated in a unique hydrogen permeation-ultrasonic scanning experiment. Both the observed time until initiation for HIC cracks and the crack growth rate show excellent agreement with the model calculations. The experiment in combination with the HIC model shows that defects initiate and propagate through segregation zones with a low fracture toughness. As soon as the defects reach the end of the segregation zone the HIC growth stops. The fracture toughness of the segregation zone as well as the bulk fracture toughness were determined by fitting the HIC model to the experimental data.

Subject
Hydrogen induced cracking, Crack growth, Fracture toughness, Surface defects, Hydrogen concentration, Crack initiation, Pipelines, Permeation, Experimental data, Defects, Steel, Hydrophobic interaction chromatography, Hydrogen
Keywords:
Hydrogen, HIC, cracking, permeation, ultrasonic, inspection, modelling, fracture toughness, inclusions, segregation
© 1995 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).
1995
Association for Materials Protection and Performance (AMPP)
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