Direct correlations are made between the extent of chromium depletion at grain boundaries and intergranular stress corrosion cracking (IGSCC) of 304 stainless steel during slow-strain-rate (SSR) tensile tests in 288 C aerated water. IGSCC was found to depend on the minimum chromium concentration, the spacing of carbides and the width of chromium depleted zone at grain boundaries. Modifying any one of these interfacial characteristics impacted IG cracking and ductility. Under the conditions of the SSR test, IGSCC is sharply increased as the grain boundary chromium concentration drops below ~13.5 wt%. The presence of a semi-continuous distribution of carbides at grain boundaries prompted some IG cracking and ductility loss without significant chromium depletion. This cracking was eliminated by heat treating to form isolated carbides at boundaries. Very narrow chromium depletion widths (<4 nm) enhanced IGSCC over that observed for stainless steel with semi-continuous carbides. The extent of IG cracking and the degree of embrittlement also increased with the width of the chromium depletion zone.

Subject
Water, Materials, Carbides, Intergranular stress corrosion cracking, Chromium, Density, Interfaces, Heat, Fracture, Grain boundary, Heat treatment, Stress corrosion cracking, Ductility
© 1991 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).
1991
Association for Materials Protection and Performance (AMPP)
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