SEDL / STP / STP856-EB / STP34526S

Cleavage Fracture of Steel in the Ductile-Brittle Transition Region

Rosenfield, AR
Research leader and principal research scientist, Battelle-Columbus, Columbus, OH

Shetty, DK
Research leader and principal research scientist, Battelle-Columbus, Columbus, OH

Pages: 14    Published: Jan 1985

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Abstract

Fracture-toughness experiments on ASTM A508 (Unified Numbering System [UNS] K13502) steel within the ductile-brittle transition region are a combination of both ductile and brittle behaviors, leading to severe data scatter. Both crack blunting and dimpled rupture are terminated by unstable cleavage. At a lower test temperature, cleavage during blunting predominates, whereas at a higher test temperature, cleavage tends to occur after some stable crack growth. It is suggested that this behavior results from the existence of a distribution of “trigger” sites in the microstructure (for example, inclusions and carbides). Methods for eliminating the dimpled-rupture contribution to the test record are discussed and are shown to be useful for predicting large-specimen behavior.