Development of Accurate Quantitative Analytical Methods to Determine Trace Amounts of Carbon, Sulfur, and Oxygen in Steel

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1 JFE No p Development of Accurate Quantitative Analytical Methods to Determine Trace Amounts of Carbon, Sulfur, and Oxygen in Steel YASUHARA Hisao MIYAGI Chiyoko JFE Ph.D. JFE Abstract: Accurate and rapid quantitative analytical methods for trace amounts of carbon, sulfur, and oxygen in steel which infl uence material properties directly were investigated. Amount of accelerator was optimized to determine carbon and sulfur by the combustion method simultaneously. And preheating conditions of crucible and accelerator were determined to reduce blank values. A new pretreatment process using ion sputtering has been developed to remove contamination on the sample surface to determine oxygen content in steel. This permits to remove contamination that cannot be eliminated by conventional pretreatment methods such as electro-polishing and chemical polishing. 1. µg/g - He - 1 7) 8) µg/g 29

2 Table 1 JSS JSS CH3COOH-HClO4 CrO3-H3PO4 HF-H2O2 Sn.18 g/ 2.2 LECO - CS-444LS S - LECO TC-436 Model-595 auger electron spectrometry, AES SiO CO2 SO2 Cu W W Sn W Cu SO2 SO3 W Sn W Sn W Sn( 4 1) Table 1 No. 3 No g 1 g Fig. 1 W Sn W Sn W Sn 1. g Sn.18 g W 4. g Table 1 Chemical composition of the samples (mass%) Sample C Si Mn P S Al O No NA No NA No NA No NA JSS NA NA JSS NA NA JSS NA JSS NA JSS NA NA JSS GS-2c NA.1 8 JSS GS-3c NA.3 5 JSS GS-5c NA.13 High purity iron NA.1 Bearing steel NA. 5 NA: Not analyzed JFE No

3 no (a) Carbon W Sn W Sn Accelerator no W Sn W Sn Accelerator (b) Sulfur Fig. 1 Infl uence of the kind of accelerators on carbon and sulfur analytical intensities (Combustion condition: sample, 1. g; accelerators, 1 g (n 5)) Fig. 2 Fig. 2 W W W W 1. g W X X W W W 9,1) W CO2 SO2 W 1. g.25 g.5 g.25 g W.5 g Sn Fig g W.5 g Sn Sn Sn.18 g Sn Sn X SnO2 Sn Sn 1. g.18 g Tungsten (g) (a) Carbon (a) Carbon Tin (g) Fig Tungsten (g) (b) Sulfur Infl uence of tungsten accelerator amount on carbon and sulfur analytical intensities (Combustion condition: sample, 1. g; Sn,.18 g (n 5)) Fig (b) Sulfur Tin (g) Infl uence of tin accelerator amount on carbon and sulfur analytical intensities (Combustion condition: sample, 1. g; W,.5 g (n 5)) 31 JFE No

4 C 2 h 46 C 15 min 5 No. 2 Table 2 A E D JIS 43 C 1 min E Table 2 D E D Table 3 1 µg/g 1 µg/g Table 2 Effects of pretreatments of crucible, accelerator and sample on carbon and sulfur analytical intensities Treatment A B C D E Crucible no (a) (a) (a) (a) Accelerator no no (b) (b) (b) Sample (No. 2) no no no (c) (d) Carbon analytical intensity Mean (arb.unit) SD* RSD (%)** Sulfur analytical intensity Mean (arb.unit) SD RSD (%) n 1 * Standard deviation ** Relative standard deviation (a) Heating at 1 11 C for 2 h (b) Heating at 46 C for longer than 15 min (c) Sample addition into a crucible at high temperature (d) Preheating at 43 C for 1 min Table 3 6 µg/g 3.2 Analytical results of carbon and sulfur in certifi ed reference steels (mass%) Element Sample Certified Continuous repetition value Mean SD RSD (%) Carbon No.1* JSS JSS Sulfur JSS ** 1.5*** JSS JSS * Non-certified material ** Non-certified value *** n ) µg/g Fig. 4 Fig. 4 Intensity (a.u.) (a) (b) (c) High purity iron Intensity (a.u.) Bearing steel Thickness (nm) Depth profiles of samples after pretreatment in (a) CH3COOH-HClO4, (b) CrO3-H3PO4, and (c) HF-H2O JFE No

5 2 nm 12 nm 2 cm 2 1 µg/g 3 µg/g 12, min 1 min 2 nm - 12, ) Fig. 5 Sample holding bar Fig. 6 DC power supply Fig. 5 Anode Slide valve Top Side Bottom To oxygen analyzer Schematic of the pretreatment equipment Sample Intensity ratio of Pd 5 1 Analysis of the sample surface by electron probe minroanalyzer 6 Pa 1 V Pd 6s Pd EPMA JSS GS-2c Fig. 6 Pd Table 4 2) GD GD 1 2 µg/g Table 4 He 33 JFE No

7 15.5 σ.22.28 RSD(%) 1.37 1.61 x 3.3 4..7 3.1 σ.27.34 RSD(%) 8.29 8.56 x 1.7 2.6.9 1.6 σ.21.56 RSD(%) 12.7 21.

6 Table 4 JSS GS-2c Bearing steel High purity iron 4. Comparison of the analytical values of oxygen with and without glow discharge pretreatment ( µg/g) Inert gas fusion method With GD pretreatment Without GD pretreatment Difference CPAA x σ RSD(%) x σ RSD(%) x σ RSD(%) CPAA : Analytical values obtained by charged particle activation analysis 1 - a W Sn 1. g W.5 g Sn.18 g b 1 11 C 2 h W Sn 46 C 15 min µg/g 1 Bunseki Kagaku vol p Ashino, T.; Takada, K.; Morimoto, Y.; Yasuhara, H.; Kurosaki, M.; Abiko, K. Mat. Trans. JIM. vol. 41, 2, p Takada, K.; Morimoto, Y.; Yoshioka, K.; Murai, Y.; Abiko, K. Phys. Stat. Sol. (a). vol. 167, 1998, p Bunseki Kagaku vol p vol. 25 no p vol p Lawrenz, D. Phys. Stat. Sol. (a). vol. 167, 1998, p Bunseki Kagaku vol p vol p vol p. S vol p Yasuhara, H.; Shimura, M.; Yoshioka, K. Phys. Stat. Sol. (a). vol. 16, 1997, p vol p Ise, T.; Nuri, Y.; Kato, K.; Ohishi, T.; Matsunaga, H. ISIJ Int. vol. 38, 1998, p vol p Bunseki Kagaku vol p Yasuhara, H.; Shimura, M.; Yoshioka, K.; Abiko, K.; Iwai, H.; Niida T. Phys. Stat. Sol. (a). vol. 189, 22, p CAMP-ISIJ vol p CAMP-ISIJ vol. 17 no p Shikano, K.; Yonezawa H.; Shigematsu T.J. of Radioanalytical and Nuclear Chem., Articles. vol. 167, 1993, p. 81. JFE No

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