SYMPOSIA PAPER Published: 01 January 1989

The Crack Velocity- Relationship for AISI 4340 in Seawater Under Fixed and Rising Displacement


An experimental study was conducted to determine if the type of loading, excluding cyclic loading, has an effect on the crack velocity/stress-intensity relationship for environmentally assisted cracking. Compact tension specimens made of AISI 4340, σ() = 1095 MPa (159 ksi), were tested in synthetic seawater under constant load, constant crack mouth opening displacement (CMOD), constant stroke rate (rising displacement) ranging over four orders of magnitude, and dual stroke rate. The results show that when crack growth is assisted by the environment the same a-KI curve is obtained for each type of loading within the bounds of data scatter. These observations are supported by calculations which show that the cracktip opening displacement rate, a measure of crack-tip strain rate, is insensitive to the different types of loading for this system.

Author Information

Mayville, RA
Arthur D. Little, Inc., Cambridge, MA
Warren, TJ
Arthur D. Little, Inc., Cambridge, MA
Hilton, PD
Arthur D. Little, Inc., Cambridge, MA
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Developed by Committee: E08
Pages: 605–614
DOI: 10.1520/STP18846S
ISBN-EB: 978-0-8031-5081-2
ISBN-13: 978-0-8031-1250-6