Quantitative Analysis of Precipitates in Ti Added Low Carbon Steel by SAXS and TEM

Abstract

Synopsis : Transmissionelectronmicroscopy(TEM)isapowerfulmethodforanalyzingfineprecipitatesbecauseitcanmeasurethesizeofprecipitates directly. In contrast, small angle X-ray scattering (SAXS) covers much larger observation volumes and has an advantage in the quantitativity of statistical representative values. However the consistency between results obtained by SAXS and TEM has been less discussed quantitatively, especially in the case of precipitates having anisotropic shapes. In this study, the quantitativity of SAXS was investigated by comparing SAXS and TEM analysis of TiC in high strength steels. Samples with various size distribution of TiC were prepared. The average size, number density and volume fraction of TiC were obtained by SAXS analysis performed on these samples using both sphere and disk form factor. Regardress of the form factor, the average size and volume fraction were almost the same, whereas the number density differed by one order. The average size of TiC measured by SAXS analysis was consistent with that obtained by TEM. Since it is considered that the difference in the number density depending on the form factors is attributed to an error due to the overestimation of size distribution width, the average numberdensitywasdefinedtocorrectthisoverestimation.Theaveragenumberdensitycalculatedfromtheresultsusingbothformfactors well agreed, which were a reasonable value. It was found that using sphere form factor with good convergence is effective to discuss the average information of the precipitates.