SEDL / STP / STP827-EB / STP37114S

Topographic Examination of Fracture Surfaces in Fibrous-Cleavage Transition Behavior

Kobayashi, T
SRI International, Menlo Park, Calif.

Irwin, GR
University of Maryland, College Park, Md.

Zhang, XJ
University of Maryland, College Park, Md.

Pages: 18    Published: Jan 1984

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Abstract

In order to increase understanding of the fibrous-to-cleavage fracture transition phenomenon, an examination of the fracture surfaces of A36 and A533B steel was made with a scanning electron microscope and stereoscopic photographs.

By topographical characterization of matching sites of conjugate fracture surfaces, the crack tip opening stretch (δ), the fracture process zone size (through the measurement of fracture surface height variation), and the deformation of grains (such as the lifting of unbroken ligaments from the fracture surfaces) were determined. Topographical characterization of two sides of some fracture surfaces also revealed local fracture processes such as formation of voids ahead of a crack tip and crack extension from the voids. Finally, fractographic estimates of crack tip opening displacement were correlated to the fracture toughness measurement.