SYMPOSIA PAPER Published: 01 January 1994
STP15209S

Grain-by-Grain Study of the Mechanisms of Crack Propagation During Iodine Stress Corrosion Cracking of Zircaloy-4

Source

This paper describes the tests conducted to determine the conditions leading to cracking of a specified grain of metal, during the iodine stress corrosion cracking (SCC) of zirconium alloys, focusing on the crystallographic orientation of crack paths, the critical stress conditions, and the significance of the fractographic features encountered. In order to perform crystalline orientation of fracture surfaces, a specially heat-treated Zircaloy-4 having very large grains, grown up to the wall thickness, was used. Careful orientation work has proved that intracrystalline pseudo-cleavage occurs only along basal planes. The effects of anisotropy, plasticity, triaxiality, and residual stresses originated in thermal contraction have to be considered to account for the influence of the stress state. A grain-by-grain calculation led to the conclusion that transgranular cracking always takes place on those bearing the maximum resolved tensile stress perpendicular to basal planes. Propagation along twin boundaries has been identified among the different fracture modes encountered.

Author Information

Haddad, RE
CNEA (Gcia. de Desarrollo), Buenos Aires, Argentina
Dorado, AO
ASTRA S. A., Chubut, Argentina
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Developed by Committee: B10
Pages: 559–575
DOI: 10.1520/STP15209S
ISBN-EB: 978-0-8031-5286-1
ISBN-13: 978-0-8031-2011-2