Low-alloy steels are widely used for the production of pipes, automotive and aerospace bodies, railway lines and offshore/onshore structural engineering plates. High-strength low- alloy steel is used in these areas due to its corrosion resistance properties. Accurate and fast elemental analysis is a critical requirement during the production of steel.
Integration of the revolutionary ED core into the Zetium spectrometer sees two technologies, namely WD- and EDXRF, converging to make a unique and powerful analytical heart called SumXcore technology, which delivers specific benefits for metals applications, such as:
- reduced measurement times
- identification and flagging of unexpected elements in production
- fast sample screening
- spectrum archiving
This data sheet demonstrates the time savings achieved with SumXcore technology for the analysis of low-alloy steel by XRF.
Instrumentation and software
The measurements were performed using a Zetium XRF spectrometer configured with a 2.4 kW Rh SST R-mAX X-ray tube, a WD core, which is made up of the appropriate collimators, crystals and detectors for WDXRF analysis, and an ED core, which is a fixed EDXRF channel capable of capturing a complete EDXRF spectrum simultaneously with WDXRF measurements. All measurements were conducted using the state-of-the-art SuperQ software package.
Table 1. Elemental and concentration ranges analyzed with their calibration results
Twenty certified reference materials from the Bureau of Analysed Standards (BAS) - SS 401/1 – SS 410/1 series and SS 451/1 – SS 460/1 series - were used to set up a calibration for the analysis of 20 elements. Details on the compositional and concentration ranges are listed in Table 1. The standards were freshly surfaced prior to analysis with a Herzog grinding machine using 150 grit Al2O3 sandpaper.
One application was set up using the optimum combination of both technologies where certain elements were measured using the WD core and others using the ED core. This was done without compromising the analytical requirements for accuracy and precision. Measurements were performed using a 27 mm collimator mask. The elements performed using simultaneously WD and ED cores were measured using a Al 750 µm filter. For all ED core conditions a 0.8 mm attenuator was used. Calibration RMS values (root mean square error) and K factors (weighted standard deviation) as well as low limits of detection (LLD) are also reported in Table 1. The measurement times for the novel combination of WD and ED measurements in one are compared to a classical WD core-only setup in Table 2, showing a significant time reduction of 36%.
Table 2.Application measurement time using simultaneously WD and ED cores of the Zetium spectrometer
To determine the optimum combination of analytical conditions, such that the analytical performance remains uncompromised, a comparison between the WD core and ED core setups was made for all elements of interest. This process resulted in an application where C, Si, Al, P, S, Ti, Co, Sn, Sb and Pb were measured on the WD core and all other elements on the ED core. Ti, Co, Sn, Sb and Pb were measured simultaneously with the ED core. Since elements are measured simultaneously on the ED core at the condition that kV, mA and filter are the same, the analysis time is determined by the elements with the lowest sensitivity and/or the lowest concentration (Pb, Sn, Sb, Mo, Nb and Zr in this case). The optimal combination of WD and ED for these elements resulted in an analysis time of 64 s for these elements.
Accuracy and precision
Table 3 demonstrates the achievable accuracy and precision (repeatability) of the combined application when measuring a certified low-alloy steel standard (SS 454/1) as routine samples. The obtained results confirm the accuracy of the combined application, delivering concentration values close to the certified values. It can also be seen that the application delivers consistent results, with excellent repeatability values.
Table 3. Accuracy and precision of the SumXcore application (SS454/1)
The results clearly demonstrate that the combination of WD- and EDXRF incorporated in the Zetium spectrometer delivers faster measurement times for the analysis of low-alloy steels. The increase in speed is achieved without a loss in analytical performance and the stability of the Zetium spectrometer ensures repeatability close to the theoretical limit. These two factors allow improved sample throughput, which is highly desirable where fast analytical response is required, for example during steel manufacturing.