IN SITU NEUTRON DIFFRACTION STUDIES OF THE MICROSTRUCTURE RESPONSE OF THE PLAIN FERRITIC STEEL ON TENSILE STRAINING
V. Davydov1,2
1Nuclear Physics Institute, 250 68 Řež, Czech Republic
2Faculty of Nuclear Sciences and Physical
Engineering, Czech Technical University in Prague, Břehová 7, 115 19 Prague,
Czech Republic
Present neutron diffraction study is aimed on investigation of the
response of selected lattice plains in the polycrystalline material in situ
upon tensile loading. For this purpose, the 0.1C-0.4Mn construction steel was
selected as a simple model material. The tensile deformation test was performed
in the incremental mode in which each individual deformation step was followed
by unloading. The neutron diffraction spectra were collected both upon loading
and unloading and behavior of the diffraction profiles in elastic as well as in
plastic region of the deformation curve was examined in detail.
Whereas
the behavior of the lattice strains during straining and evolution of the
residual intergranular strains (stress type I) have been already described in
other papers, the present work focused mainly on profile broadening effects
measured in the same deformation regime. The estimate of microstress (root mean
square stress) evolution was done by using the single-line profile analysis
method. Comparison of microstress values in loaded/unloaded state and in
elastic and plastic region offers interesting possibility to separate the
contribution of the type II and type III microstresses.
The modification of the TMF [1] method
developed for evaluation of the single-line diffraction profiles from
high-resolution neutron powder diffractometers is proposed. More sophisticated
real space model [2] is used for the distortion and crystallite size broadening
of the diffraction lines.
1. P. Strunz, P. Lukas, D. Neov,
J. of Neutr. Res., 9 (2001) 99-106.
2. G. Ribarik, T. Ungar, J. Gubicza,
J. Appl. Cryst., 34 (2001) 669-676.
This
work is supported by the Ministry of Education of Czech Republic (MSMT 2486
G1).