Vn. Shivanyuk et al., Hydrogen-enhanced microplasticity of austenitic steels studied by means ofinternal friction, MAT SCI E A, 300(1-2), 2001, pp. 284-290
Hydrogen-induced damping at low temperatures is studied in austenitic steel
s Cr18-Ni16-Mn10, Cr25-Ni20 and Cr25-Ni40. The orientation dependence of th
e hydrogen-caused Snoek-like relaxation measured in single crystals gives e
vidence for the orthorhombic symmetry of the s-H complexes created by hydro
gen and substitutional atoms in the gamma solid solution. The observed spli
tting of the Snoek-like relaxation peak is analysed on the basis of the rel
axation theory caused by non-cubic defects in the cubic matrix. It is shown
that the increase in the chromium and nickel content changes the symmetry
of the s-H complexes. Based on the analysis of the experimental data in Arr
henius coordinates and on the temperature of the Snoek-like peak caused by
the local jumps of hydrogen atoms, one can suppose that chromium increases
the enthalpy of the local migration of hydrogen atoms in s-H complexes wher
eas nickel decreases it. Hydrogen charging diminishes the critical strain a
bove which internal friction depends on the strain and increases the dampin
g in its strain-dependent range. The results are interpreted in terms of hy
drogen-caused decrease in the start stress of the localised plastic deforma
tion and an increased mobility of emitted dislocations, which is consistent
with the hypothesis of the hydrogen-enhanced localised plasticity. (C) 200
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