| Grade | Wall Thickness/mm | Tensile Strength σb/MPa |
Yield Strength σ0.2/MPa |
Elongation δ/% |
Reference Value | ||||
| ≥ | HardnessHB | Main Microstructure | |||||||
| QT400-18 | >30~60 | 390 | 250 | 18 | 130~180 | Ferrite | |||
| >60~200 | 370 | 240 | 12 | ||||||
| QT400-15A | >30~60 | 390 | 250 | 15 | 130~180 | Ferrite | |||
| >60~200 | 370 | 240 | 12 | ||||||
| QT500-7A | >30~60 | 450 | 300 | 7 | 170~240 | Ferrite+Pearlite | |||
| >60~200 | 420 | 290 | 5 | ||||||
Source: https://www.landeevalve.com/domestic-valve-materials-frequently-used-technical-standard-ductile-iron-specification-mechanical-property.html