Title

Structure/property/continuum synthesis of ductile fracture in inconel alloy 718

Document Type

Article

Publication Date

5-1-1978

Abstract

Two microscopic ductile fracture processes have been established in a fracture tough superalloy, Inconel 718, aged to five strength levels. At yield strengths less than 800 MPa, the mechanism is a slow tearing process within large pockets of inhomogeneous carbides and nitrides, giving rise to plane strain fracture toughness (K IC)values greater than 120 MPa-m1/2. At yield strengths greater than 900 MPa, the mechanism involves fracture initiation at carbides and nitrides followed by off crack plane void sheet growth nucleated at the Laves (σ) phases. Here, the fracture toughness drops to about 80 MPa-m1/2. A Mode I normal strain growth model for low yield strength conditions and a shear strain void sheet model for high yield strength ones are shown to model KIC data obtained from a J-integral evaluation of compact tension results. © 1978 American Society for Metals and the Metallurgical Society of AIME.

Publication Title

Metallurgical Transactions A

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