University of Illinois Urbana-Champaign

Elastoplastically accommodated hydride formation and embrittlement

Lufrano, Jon M.; Sofronis, Petros; Birnbaum, Howard K.

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https://hdl.handle.net/2142/112548

Description

Title
Elastoplastically accommodated hydride formation and embrittlement
Author(s)
  • Lufrano, Jon M.
  • Sofronis, Petros
  • Birnbaum, Howard K.
Issue Date
1997-02
Keyword(s)
  • Hydride Formation
  • Embrittlement
Abstract
In a previous work, the authors (1996) investigated stress driven diffusion of hydrogen in a hydride forming system whose constitutive response was modeled as linearly elastic. In the present work the more realistic constitutive assumption of a purely elastic hydride accommodated elastoplastically by the surrounding matrix is used. Due to the nonlinearity in the material deformation, the classical description and calculation of the accommodation energy of formation and interaction energy with an external stress using Eshelby's methodology are no longer valid. The elastoplastic deformation of the matrix due to the volume dilatation induced by the hydride and the interaction of this deformation with externally applied stresses are studied. The energetics of the hydride formation is revisited and the terminal solid solubility of hydrogen in solution is defined on the basis of the total elastoplastic work done on the system by the forming hydride and the external loads. Hydrogen diffusion and hydride formation coupled with the elastoplastic deformation of the material are modeled at a blunting crack tip in the case of the niobium-hydrogen system. Nonlinear finite element analysis is used to monitor the local distribution and time evolution of hydrogen concentration, hydride volume fraction, stress and strain as the externally applied loads increase. A Griffith fracture criterion allows the calculation of a critical hydride size in the neighborhood of the crack tip at which cracking of the hydride particle by the local stresses is energetically favorable. Using this criterion for fracture initiation, one can predict the reduced fracture resistance of hydride forming systems quantitatively and investigate the fracture toughness dependence of the material on initial concentration and loading rate.
Publisher
Department of Theoretical and Applied Mechanics. College of Engineering. University of Illinois at Urbana-Champaign
Series/Report Name or Number
  • TAM R 846
  • 1997-6007
ISSN
0073-5264
Type of Resource
text
Language
eng
Permalink
http://hdl.handle.net/2142/112548
Sponsor(s)/Grant Number(s)
Energy Department 97/02 DEFG 02 91 ER 45439 97/02
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.