University of Illinois Urbana-Champaign

Numerical study of intergranular fracture and oxygen embrittlement in elastic-viscoplastic solid

Carranza, Fernando L.; Haber, Robert B.

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https://hdl.handle.net/2142/112567

Description

Title
Numerical study of intergranular fracture and oxygen embrittlement in elastic-viscoplastic solid
Author(s)
  • Carranza, Fernando L.
  • Haber, Robert B.
Issue Date
1997-10
Keyword(s)
  • Crack Propagation And Arrest
  • Corrosion And Embrittlement
  • Grain Boundaries
  • Elastic-viscoplastic Material
  • Finite Elements
Abstract
We present results from a numerical investigation of fracture along an embrittled surface embedded in an elastic-viscoplastic solid, an idealized model for high-temperature intergranular fracture in nickel-base superalloys. The formulation includes coupled models for the mechanical response, stress-assisted diffusion of oxygen, and a moving cohesive interface that determines crack initiation, growth and arrest. The entire system is formulated in a frame that translates with the crack tip and is implemented in an adaptive, space-time finite element code that supports both transient and direct steady-state calculations. We present a criterion for stable crack growth specific to the moving cohesive interface model and apply it to studies of fracture along a planar grain boundary with uniform cohesive properties. No stable solutions were found for the steady case. In the transient case, the stability criterion resolves a lack of uniqueness in the incremental solutions for growing cracks. Results are reported for monotonic loading to failure, linear ramp to sustained hold at a peak load level and cyclic loading. We investigate the sensitivity of the response to the loading rate, the cohesive interface properties and the degree of overload past crack initiation. Finally, we extend the cohesive interface model and the stability criterion with a phenomenological model for oxygen embrittlement and report the effects of embrittlement on steady-state response.
Publisher
Department of Theoretical and Applied Mechanics. College of Engineering. University of Illinois at Urbana-Champaign
Series/Report Name or Number
  • TAM R 863
  • 1997-6024
ISSN
0073-5264
Type of Resource
text
Language
eng
Permalink
http://hdl.handle.net/2142/112567
Copyright and License Information
Copyright 1997 Board of Trustees of the University of Illinois

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Technical Reports - Theoretical and Applied Mechanics (TAM) PRIMARY
TAM technical reports include manuscripts intended for publication, theses judged to have general interest, notes prepared for short courses, symposia compiled from outstanding undergraduate projects, and reports prepared for research-sponsoring agencies.