Hydrogen Embrittlement in Metals:Analysis of Directionality of Hydrogen Diffusion Assisted by Stress and Strain
Hydrogen diffusion within a metal or alloy is conditioned by the stress-strain state therein.For that reason it is feasible to consider that hydrogen diffuses in the material obeying a Fick type diffusion law including an additional term to account for the effect of the stress state represented by the hydrostatic stress.According to this law hydrogen diffuses not only to the points of minimum concentration (driven by its gradient),but also to those of maximum hydrostatic stress (driven by its gradient),the diffusion itself being also conditioned by the gradient of plastic strain.In this paper the hydrogen transport by diffusion in metals is modelled in notched specimens where loading generates a triaxiality stress state.To this end,two different approaches of stress-assisted hydrogen diffusion,one-dimensional (1D) and two-dimensional (2D),were compared in the vicinity of the notch tip in four notched specimens with very distinct triaxiality level at two different loading rates.The 2D approach predicts lower values of hydrogen concentration than the 1D approach,so that a loss of directionality of hydrogen diffusion towards the location of highest hydrostatic stress appears in the 2D case.This loss of directionality of hydrogen diffusion depends on both notch geometry parameters (radius and depth) and loading rate (or straining rate).
Hydrogen diffusion Numerical models Notched samples Directionality of diffusion
Jesús Toribio Viktor Kharin Diego Vergara Miguel Lorenzo
Department of Materials Engineering,University of Salamanca,Avda.Requejo 33,49022 Zamora,Spain Department of Mechanical Engineering,University of Salamanca,Avda.Fernando Ballesteros 2,37700 Béjar
国际会议
北京
英文
1-8
2013-06-16（万方平台首次上网日期，不代表论文的发表时间）