Table 3: Ferrite and bainite volume fractions of the heat-treated samples analyzed by metallography and image analysis.
| Sample name | Starting microstructure | Austenitizing temperature (℃) | Austenitizing time (min) | Ferrite and bainite volume fractions |
| HTS.1 | Pearlite ferrite | 855 | 30 | 62% Ferrite |
| 35% Bainite | ||||
| HTS.2 | Martensite | 855 | 30 | 55% Ferrite |
| 45% Bainite | ||||
| HTS.3 | Pearlite ferrite | 900 | 180 | 37% Ferrite |
| 63% Bainite | ||||
| HTS.4 | Martensite | 900 | 180 | 53% Ferrite |
| 46% Bainite | ||||
| HTS.5 | Pearlite ferrite | 900 | 120 | 45% Ferrite |
| 55% Bainite | ||||
| HTS.6 | Martensite | 900 | 120 | 05% Ferrite |
| 95% Bainite | ||||
| HTS.7 | Pearlite ferrite | 950 | 60 | 40% Ferrite |
| 60% Bainite | ||||
| HTS.8 | Pearlite ferrite | 900 | 120 | 23% Ferrite |
| 77% Bainite | ||||
| HTS.9 | Martensite | 900 | 120 | 29% Ferrite |
| 71% Bainite | ||||
| HTS.10 | Pearlite ferrite | 900 | 120 | 40% Ferrite |
| 40% Ferrite | ||||
| HTS.11 | Martensite | 900 | 120 | 04% Ferrite |
| 95% Bainite | ||||
| HTS.12 | Pearlite ferrite | 900 | 120 | 06% Ferrite |
| 94% Bainite | ||||
| HTS.13 | Martensite | 900 | 120 | 03% Ferrite |
| 97% Bainite | ||||
| HTS.14 | Pearlite ferrite | 900 | 120 | 05% Ferrite |
| 95% Bainite |