Table 1: Comparison of the ASTM standard and the chemical composition of the commercial material from spectrographic analysis.
| Chemical composition (%) | Carbon | Iron | Nitrogen | Oxygen | Hydrogen | Others |
| ASTM standard [13] | < 0.08 | < 0.3 | < 0.03 | < 0.25 | < 0.015 | < 0.1 |
| Spectrographic analysis | 0.01 | 0.12 | 0.008 | 0.12 | 19 ppm |