On the Accuracy of Analytical Results of the Common Elements in Iron and Steel Obtained by Direct-reading Spectrometry

Aiming to raising of accuracy of analytical results of 8 common elements in iron and steel by the ARL 4460 direct-reading spectrometer, testing for some influential factors, especially for determinations of carbon and sulfur, was made. The following measures were found to be effective for improving both the accuracy and precision of the determinations: ① light source parameters set during manufacturing were modified by lowering the time of development from 10 s to 2 s, the time of pre-ignition from 7 s to 6 s, and time of exposure from 8 s to 3 s; ② for the determination of C, S and P, high-purity argon (99.999%) with its pressure of 0.30 MPa, should be used; ③ a fine grinder should be used in preparing sample in order to make the surface of sample clear and plain, as well as to have clear grain; ④ in determination of carbon, temperature of sample should be kept below 40 ℃, and to keep the finess of its grain in its original state; ⑤ room temperature of the lab should be kept constant around 25 ℃, and correction of working curves should be made every 8 h; ⑥ in determination of sulfur, samples with relatively higher temperature should be cooled to near room temperature before analysis, and at least 3 evenly deposited excitation sites should be taken as well as correction and standardization of the standard working curve should be made.