SYMPOSIA PAPER Published: 01 January 1972

Fracture Toughness of Duplex Structures: Part II — Laminates in the Divider Orientation


Laminates containing 25 percent of tough (unaged) maraging steel plates and 75 percent of brittle (aged) maraging steel plates were prepared by a special diffusion bonding and heat treating technique so that the thickness of the tough constituent was either 0.02, 0.04, 0.06, or 0.08 in. Compact tension fracture toughness specimens were machined so that the laminates were parallel to the sides of the specimens. They were then fractured according to the recommendations of the ASTM and three indices of toughness were measured: KIc, as recommended by the ASTM, Komax based on the maximum load and original crack length and Kimax, based on the maximum load and instantaneous crack length. Four tests were performed at each thickness of the tough constituent; two each at crack lengths of approximately 0.30 and 0.55 in. The plane-strain fracture toughness of the laminates was slightly higher than KIc of the monolithic brittle constituent and was independent of either crack length or the dimensions of the tough constituent. Regardless of the thickness of the tough phase the composite toughness was highest for specimens containing cracks 0.30 in. long when the throughness was measured in terms of Komax or Kimax. The thoughnessas a function of thickness exhibited a relative maximum when the tough phase was 0.04 in. thick and a relative minimum when the tough phase was 0.06 in. thick for both the 0-30 and 0.55-in. crack lengths. The experimental results are in broad agreement with a proposed model for crack extension in the divider orientation.

Author Information

Antolovich, SD
University of Cincinnati, Cincinnati, Ohio
Kasi, K
University of Cincinnati, Cincinnati, Ohio
Chanani, GR
University of Cincinnati, Cincinnati, Ohio
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Developed by Committee: E08
Pages: 135–150
DOI: 10.1520/STP38823S
ISBN-EB: 978-0-8031-5575-6
ISBN-13: 978-0-8031-5529-9