Apparent Bias in the X-Ray Fluorescence Determination of Titanium in Selected NIST SRM Low-Alloy Steels

Abstract

X-ray fluorescence results of the analysis of titanium in NIST SRM 1165 and 1264 low-alloy steels were found to be significantly different from the certified values. These differences appear to be unique to the XRF results since results from other methods such as emission spectroscopy did not show any discrepancies. The microhomogeneity of selected samples was examined by electron probe microanalysis and revealed the presence of titanium inclusions containing varying amounts of zirconium, niobium, and tantalum. Differences in metallurgical uniformity are believed to be the major cause of apparent XRF bias in these SRMs. XRF analysis of the new 1760-series alloys indicates that these are more uniform and more accurate for purposes of calibration than the 1160 series and 1260 series for elements such as titanium.