Micromechanics of intergranular creep failure under cyclic loading

Journal Article · Mon Jul 01 04:00:00 EDT 1996 · Acta Materialia

DOI:https://doi.org/10.1016/1359-6454(95)00399-1· OSTI ID:264092

Giessen, E van der ^[1]; Tvergaard, V ^[2]

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1. Delft Univ. of Technology (Netherlands). Lab. for Engineering Mechanics
2. Technical Univ. of Denmark, Lyngby (Denmark). Dept. of Solid Mechanics

This paper is concerned with a micromechanical investigation of intergranular creep failure caused by grain boundary cavitation under strain-controlled cyclic loading conditions. Numerical unit cell analyses are carried out for a planar polycrystal model in which the grain material and the grain boundaries are modeled individually. The model incorporates power-law creep of the grains, viscous grain boundary sliding between grains as well as the nucleation and growth of grain boundary cavities until they coalesce and form microcracks. Study of a limiting case with a facet-size microcrack reveals a relatively simple phenomenology under either balanced loading, slow-fast loading or balanced loading with a hold period at constant tensile stress. Next, a (non-dimensionalized) parametric study is carried out which focuses on the effect of the diffusive cavity growth rate relative to the overall creep rate, and the effects of cavity nucleation and grain boundary sliding. The model takes account of the build up of residual stresses during cycling, and it turns out that this, in general, gives rise to a rather complex phenomenology, but some cases are identified which approach the simple microcrack behavior. The analyses provide some new understanding that helps to explain the sometimes peculiar behavior under balanced cyclic creep.

• OSTI ID: 264092
• Journal Information: Acta Materialia, Journal Name: Acta Materialia Journal Issue: 7 Vol. 44; ISSN XZ504Y; ISSN 1359-6454
• Country of Publication: United States
• Language: English

Related Subjects

36 MATERIALS SCIENCE
CAVITIES
CRACKS
CREEP
DIFFUSION
FAILURES
FATIGUE
GRAIN BOUNDARIES
MATHEMATICAL MODELS
METALS
NUMERICAL ANALYSIS
RESIDUAL STRESSES
STRAINS
STRESSES