On macroscopic and microscopic analyses for crack initiation and crack growth toughness in ductile alloys

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Detail(s)

Original languageEnglish
Pages (from-to)233-248
Journal / PublicationMetallurgical Transactions A
Volume16
Issue number2
Publication statusPublished - Feb 1985
Externally publishedYes

Abstract

Relationships between crack initiation and crack growth toughness are reviewed by examining the crack tip fields and microscopic (local) and macroscopic (continuum) fracture criteria for the onset and continued quasi-static extension of cracks in ductile materials. By comparison of the micromechanisms of crack initiation via transgranular cleavage and crack initiation and subsequent growth via microvoid coalescence, expressions are shown for the fracture toughness of materials in terms of microstructural parameters, including those deduced from fractographic measurements. In particular the distinction between the deformation fields directly ahead of stationary and nonstationary cracks are explored and used to explain why microstructure may have a more significant role in influencing the toughness of slowly growing, as opposed to initiating, cracks. Utilizing the exact asymptotic crack tip deformation fields recently presented by Rice and his co-workers for the nonstationary plane strain Mode I crack and evoking various microscopic failure criteria for such stable crack growth, a relationship between the tearing modulus TR and the nondimensionalized crack initiation fracture toughness JIc is described and shown to yield a good fit to experimental toughness data for a wide range of steels. 

Bibliographic Note

The publication is also published in "Metallurgical Transactions A, Volume 16, Issue 1".