Title: Initiation stress of delamination cracking in A2091 AI-Li alloy

Authors: Akihiro Takahashi, Toshiro Kobayashi, Hiroyuki Toda

Addresses: Graduate School, Toyohashi University of Technology, Tempaku-cho, Hibarigaoka, Toyohashi-city, AICHI 441-8580, Japan. ' Department of Production Systems Engineering, Toyohashi University of Technology, Tempaku-cho, Hibarigaoka, Toyohashi-city, AICHI 441-8580, Japan. ' Department of Production Systems Engineering, Toyohashi University of Technology, Tempaku-cho, Hibarigaoka, Toyohashi-city, AICHI 441-8580, Japan

Abstract: The measurement of the velocities of ultrasonic waves has been used to detect the delamination cracking during tensile tests in an A2091 A1-Li alloy at both liquid helium and room temperatures. The measured tensile far-field stresses at the onset of the delamination cracking are 335 and 357 MPa, at cryogenic and room temperatures, respectively. The density of delamination cracks in the alloy is estimated from the reduction in the ultrasonic wave velocity and resultant decrease in modulus of elasticity. It is estimated that the interfacial bonding strengths normal to a grain boundary are 116 and 113 MPa, at cryogenic and room temperatures, respectively. Fracture mechanics analysis has been used to estimate the onset of delamination cracking in fracture toughness tests on the basis of the results of the tensile tests. The predicted levels of far field applied stresses are much lower than those for macroscopic crack initiation at both temperatures.

Keywords: aluminium lithium alloys; delamination cracking; microcrack density; ultrasonic wave velocity; tensile tests; interfacial bonding; stress; crack initiation.

DOI: 10.1504/IJMPT.1999.036268

International Journal of Materials and Product Technology, 1999 Vol.14 No.2/3/4, pp.217 - 228

Published online: 01 Nov 2010 *

Full-text access for editors Full-text access for subscribers Purchase this article Comment on this article