The paper deals with quantitative measurements of environmental hydrogen crack growth rate on an high strength steel. In environmental hydrogen cracking, da/dt against KIi is sensitive to the loading type on mechanical toughness specimens.

In WOL specimens, applying constant C.T.O.D. (δ), the initial value of KIi is high enough to develop a large plastic zone at the crack tip in which hydrogen is trapped by the high dislocations density. Consequently, crack initiates and propagates rapidly in the specimen bulk free from hydrogen. KISH (threshold) is attained at low hydrogen concentration.

On the other hand, applying either constant load or low and constant δ˙ on C.T. specimen (Compact Tension), KIC is almost equal to KISH (threshold) and crack initiates after longer time during which the specimen bulk is hydrogenated. In stage II, da/dt is then higher than that of the first case.

Subject
Openings, Crack growth, Machinery, Crack initiation, Crack propagation, Stress cracking, Constants, Plastics, Crack length, Steel, Cracks, Stress corrosion cracking, Hydrogen
Keywords:
Environmental hydrogen, stress-intensity factors KIi and KISH, W.O.L. and C.T. specimens, crack growth rate, crack (tip) opening displacement
© 1994 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).
1994
Association for Materials Protection and Performance (AMPP)
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