Alloy steels containing as high as 4-8% alloying elements are known as low alloy steels, which are made through the addition of different elements in order to enhance a specific property of steel such as hardenability. Electric furnaces are generally used for alloy steel production. During the steel making process, the concentrations of the added elements in molten steel are altered. Hence, it is necessary to rapidly analyze the elemental composition in order to effectively control the steel making process.
The quality control of the steel making process also requires the analyses of raw materials and slag. For this purpose, X-ray fluorescence spectrometers are commonly used due to their ability to accurately and rapidly make measurements of both bulk metal and powders. This article demonstrates the capability of the ZSX PrimusIII+ wave dispersive X-ray fluorescence (WDXRF) spectrometer from Rigaku to analyze low alloy steel in order to achieve optimized process control.
ZSX PrimusIII+ WDXRF Spectrometer
The ZSX PrimusIII+ features tube over optics so that the X-ray tube can be placed above the sample, thus reducing the risk of instrument damage or contamination caused by breaking of pressed pellet samples inside the spectrometer during their measurement or transport to the measurement position. The ZSX PrimusIII+ is suitable for the steel industry where the analyses of both bulk metal and powder samples are performed as part of the process control procedure during alloy steel production.
ZSX PrimusIII+ WDXRF Spectrometer
The system software is built upon Rigaku's Flowbar interface, which facilitates the operators to improve and execute measurements through a sequence of step by step procedures. Rigaku’s another software innovation is ‘EZ analysis,’ which greatly facilitates the analysis setup and sample measurement. Moreover, the software features different kinds of statistical process control functions suitable for the steel industry.
Standard and Sample Preparation
The calibration was established using the certified standard reference materials of low alloy steel from NIST and Japan Steel Standard. The 80-grit corundum abrasive paper was used to polish the samples and the aluminum analysis was performed using the 80-grit SiC abrasive paper in order to prevent contamination from the corundum paper.
Measurement and Calibration Procedure
The ZSX Primuslll+ with a 3 kW Rh target X-ray tube was used to perform measurements. For all elements, the measurement of Kα_line was taken at 20 second counting time. A LiF(200) analyzing crystal and the scintillation counter were employed for all the heavy elements, ranging from V to Mo. A PET crystal was employed for Al and Si, while an optional Ge was utilized in order to obtain high-resolution measurement of S and P. For all light elements, a gas flow proportional counter was employed.
From the data, the representative calibration curves are plotted as depicted in Figure 1 through Figure 9. Overlap correction was carried out in the calibration of S and P in order to make correction for overlapping of Mo, as demonstrated in Figure 3 and Figure 4.
Figure 1. Calibration curve of Si
Figure 2. Calibration curve of Mn
Figure 3. Calibration curve of S
Figure 4. Calibration curve of P
Figure 5. Calibration curve of Ni
Figure 6. Calibration curve of Cr
Figure 7. Calibration curve of Mo
Figure 8. Calibration curve of Cu
Figure 9. Calibration curve of Al
Table 1 lists the accuracies of the calibration curves, while Table 2 shows the repeatability of the test results (10 times).
Table 1. Accuracy of calibration curves
||0.008 - 0.732
||0.0025 - 0.044
||0.0045 - 0.041
||0.041 - 4.1
||0.0072 - 3.08
||0.005 - 1.25
||0.0058 - 0.51
||0.0006 - 0.4
||0.0007 - 0.24
Table 2. Result of repeatability NIST1261
The results demonstrate the ability of the ZSX PrimusIII+ to precisely and rapidly analyze the elements in low alloy steel. The spectrometer can also be used for the accurate and reliable analysis of high alloys such as nickel alloy and stainless steel. It is optimized for process control of steel production, including the analyses of ferroalloys and slags.
This information has been sourced, reviewed and adapted from materials provided by Rigaku.
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