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Flow stress model for hydrogen degraded Inconel 718

Ehrlin, Niklas; Fisk, Martin LU and Bjerkén, Christina LU (2018) In Mechanics of Materials 119. p.56-64
Abstract

For life time estimation, it is desirable to capture the lowering of yield strength and premature failure that some alloys exhibits when subjected to hydrogen. For this, a mechanism based material model has been developed to simulate the hydrogen enhanced localized plasticity (HELP) for the superalloy IN718. The model accounts for the increase in mobility of moving dislocations during plastic deformation, whenever hydrogen is present in the material. Tensile tests performed at four different strain rates: 5 × 10−5, 5 × 10−4, 5 × 10−3 and 5 × 10−2 s−1 show a difference in yield behaviour between hydrogen pre-charged and uncharged samples. No strain rate dependency of the hydrogen... (More)

For life time estimation, it is desirable to capture the lowering of yield strength and premature failure that some alloys exhibits when subjected to hydrogen. For this, a mechanism based material model has been developed to simulate the hydrogen enhanced localized plasticity (HELP) for the superalloy IN718. The model accounts for the increase in mobility of moving dislocations during plastic deformation, whenever hydrogen is present in the material. Tensile tests performed at four different strain rates: 5 × 10−5, 5 × 10−4, 5 × 10−3 and 5 × 10−2 s−1 show a difference in yield behaviour between hydrogen pre-charged and uncharged samples. No strain rate dependency of the hydrogen effect could be concluded. Two different hydrogen charging methods have been used: cathodic charging with molten salt as electrolyte, and high temperature gas charging. No differences in the tensile response could be seen between the two different charging methods. The proposed model was fitted against the experimental curves using a minimizing method and model parameters were obtained. Comprising iteratively updated parameters, the model is suited for implementation in finite element software.

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author
organization
publishing date
type
Contribution to journal
publication status
published
subject
in
Mechanics of Materials
volume
119
pages
9 pages
publisher
Elsevier
external identifiers
  • scopus:85041929915
ISSN
0167-6636
DOI
10.1016/j.mechmat.2018.01.007
language
English
LU publication?
yes
id
d5c80763-4267-4195-83d6-c7d06b5c96f4
date added to LUP
2018-02-20 10:01:51
date last changed
2018-05-29 12:02:43
@article{d5c80763-4267-4195-83d6-c7d06b5c96f4,
  abstract     = {<p>For life time estimation, it is desirable to capture the lowering of yield strength and premature failure that some alloys exhibits when subjected to hydrogen. For this, a mechanism based material model has been developed to simulate the hydrogen enhanced localized plasticity (HELP) for the superalloy IN718. The model accounts for the increase in mobility of moving dislocations during plastic deformation, whenever hydrogen is present in the material. Tensile tests performed at four different strain rates: 5 × 10<sup>−5</sup>, 5 × 10<sup>−4</sup>, 5 × 10<sup>−3</sup> and 5 × 10<sup>−2</sup> s<sup>−1</sup> show a difference in yield behaviour between hydrogen pre-charged and uncharged samples. No strain rate dependency of the hydrogen effect could be concluded. Two different hydrogen charging methods have been used: cathodic charging with molten salt as electrolyte, and high temperature gas charging. No differences in the tensile response could be seen between the two different charging methods. The proposed model was fitted against the experimental curves using a minimizing method and model parameters were obtained. Comprising iteratively updated parameters, the model is suited for implementation in finite element software.</p>},
  author       = {Ehrlin, Niklas and Fisk, Martin and Bjerkén, Christina},
  issn         = {0167-6636},
  language     = {eng},
  month        = {04},
  pages        = {56--64},
  publisher    = {Elsevier},
  series       = {Mechanics of Materials},
  title        = {Flow stress model for hydrogen degraded Inconel 718},
  url          = {http://dx.doi.org/10.1016/j.mechmat.2018.01.007},
  volume       = {119},
  year         = {2018},
}