Calibration low alloy steels

Axios FAST Introduction Accurate and fast elemental analysis during the production process of steel and its base materials is a critical requirement, not only as a quality control procedure to conform to standards, but also to enable the steel producer to obtain cost savings in an ever increasing competitive environment. The Axios FAST is ideally suited for many applications where speed and accuracy are factors of prime importance.

This application note demonstrates the performance of the Axios FAST XRF spectrometer for the analysis of low alloy steel.

Instrumentation Measurements were performed using an Axios FAST simultaneous X-ray fluorescence spectrometer equipped with a 4 kW Rh SST-mAX X-ray tube, set at 60 kV/66 mA for optimal measurement conditions. A 300 µm brass filter and a brass beam stop were

mounted. Further it was equipped with:

Rh reference plate with 37 mm opening Flow counter detector window: 1 µm polypropylene for carbon analysis. Sample preparation Eleven low alloy steel standards from CKD were used to set-up the calibration. The standards were surfaced (for 5 seconds) with a 60 grit Al2O3 grinding disk, prior to measurement. The sample was put into a sample holder with a 37 mm opening.

Procedure The X-ray intensities for 16 elements were measured for 10 seconds. A calibration curve for each element was set up using the regression model incorporated in the SuperQ sofware package, taking into account interelement correction factors and line overlap correction factors.

Results The analysis speed is usually determined by the element with the lowest sensitivity (carbon in this case) and/ or the lowest concentration (Sn in this case); Table 1. Despite the short counting time of 10 seconds, excellent results were obtained for all elements, including carbon and nickel (see for examples Figures 1 and 2).

Table 1 gives an overview of the elements with their concentration ranges, their respective values for the ‘root mean square’ (RMS) error, for K and for the lower limit of detection (LLD) based on a 100 seconds counting time.

The values for RMS and K are absolute and relative indications respectively, of the magnitude of the differences between the measured

concentration and the supplied chemical concentration.

A lower value for K indicates a more accurate calibration. Since the RMS value relates to the whole concentration range, a better estimate for the absolute error of a specific element with a known concentration can be obtained by using a formula based on the K value:

For example, error estimates for Ni determinations of 1.0 and 5.0 wt% based on the calibration details in Table 1 (where K = 0.0113) would be 0.016 wt% and 0.028 wt% respectively.

Table 1. Values for K, RMS and LLD for low alloy steels

Conclusion The Axios FAST is perfectly suited for fast analysis of low alloy steels. Accurate results are obtained, even for carbon, within a counting time of only 10 seconds. Without measuring carbon, a counting time of four seconds would be sufficient to obtain identical results for the resulting elements.

Calibration low alloy steels

Login

Popular links

Support and services

Company profile

Legal information