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).