Ductile iron, Chinese standard：GB/T 1348-1998
Ductile iron cast a single test blocks of the mechanical properties and metallographic structure
| Grades | Intensity of tensionσb≥/MPa | Yield strengthσ0.2≥/MPa | Elongationδ5≥(％) | HardnessHBS | The main metallographic structure |
| QT400-18 | 400 | 250 | 18 | 130~180 | Ferrite |
| QT400-15 | 400 | 250 | 15 | 130~180 | Ferrite |
| QT450-10 | 450 | 310 | 10 | 160~210 | Ferrite |
| QT500-7 | 500 | 320 | 7 | 170~230 | Ferrite＋pearlite |
| QT600-3 | 600 | 370 | 3 | 190~270 | Pearlite＋ferrite |
| QT700-2 | 700 | 420 | 2 | 225~305 | Pearlite |
| QT800-2 | 800 | 480 | 2 | 245~335 | Pearlite or tempering |
| QT900-2 | 900 | 600 | 2 | 280~360 | Bainite or tempered martensite |
Impact performance of V-notch test specimens of single block
| Grades | Room temperature impact toughness (23±5℃)αK≥/(J/cm2) | Low temperature impact toughness (-20±2℃)αK≥/(J/cm2) | ||
| The average of three samples | Few values | The average of three samples | Few values | |
| QT400-18 | 14 | 11 | – | – |
| QT400-18L | – | – | 12 | 9 |
Mechanical properties of ductile cast attached test block and metallographic structure
| Grade | Casting wall thickness/mm | Intensity of tensionσb≥/MPa | Yield strengthσ0.2≥/MPa | Elongationδ5≥(％) | HardnessHBS | The main metallographic structure |
| QT400-18A | >30~60>60~200 | 390370 | 250240 | 1812 | 130~180 | Ferrite |
| QT400-15A | >30~60>60~200 | 390370 | 250240 | 1512 | 130~180 | Ferrite |
| QT500-7A | >30~60>60~200 | 450420 | 300290 | 75 | 170~240 | Ferrite＋pearlite |
| QT600-3A | >30~60>60~200 | 600550 | 360340 | 31 | 180~270 | Pearlite＋ferrite |
| QT700-2A | >30~60>60~200 | 700650 | 400380 | 21 | 220~320 | Pearlite |
Impact strength of V-notch test blocks of ductile iron attached
| Grade | Casting wall thickness/mm | Room temperature impact toughness (23±5℃)αK≥/(J/cm2) | Low temperature impact toughness (-20±2℃)αK≥/(J/cm2) | ||
| The average of three samples | Few values | The average of three samples | Few values | ||
| QT400-18A | >30~60>60~200 | 1412 | 119 | — | — |
| QT400-18AL | >30~60>60~120 | — | — | 1210 | 97 |
Hardness grades of ductile iron, hardness range and microstructure
| Hardness grades | HardnessHBS | The main metallographic structure | Mechanical properties (reference value) | ||
| Intensity of tensionσb≥/MPa | Yield strengthσ0.2≥/MPa | Elongationδ5≥(％) | |||
| QT-H330 | 280~360 | Bainite or tempered martensite | 900 | 600 | 2 |
| QT-H300 | 245~335 | Pearlite or tempering | 800 | 480 | 2 |
| QT-H265 | 225~305 | Pearlite | 700 | 420 | 2 |
| QT-H230 | 190~270 | Pearlite＋ferrite | 600 | 370 | 3 |
| QT-H200 | 170~230 | Ferrite＋pearlite | 500 | 320 | 7 |
| QT-H185 | 160~210 | Ferrite | 450 | 310 | 10 |
| QT-H155 | 130~180 | Ferrite | 400 | 250 | 15 |
| QT-H150 | 130~180 | Ferrite | 400 | 250 | 15 |
ISO International standard：ISO 1083:1987
Ductile iron grades and mechanical properties of single test blocks，metallographic structure
| Grade | Intensity of tensionσb≥/Mpa | Intensity of tensionσ0.2≥/Mpa | Elongationδ≥（%） | HardnessHBS | The main metallographic structure |
| 900-2 | 900 | 600 | 2 | 280~360 | Bainite or tempered martensite |
| 800-2 | 800 | 480 | 2 | 245-335 | Pearlite or tempering |
| 700-2 | 700 | 420 | 2 | 225~305 | Pearlite |
| 600-3 | 600 | 370 | 3 | 190~270 | Pearlite＋ferrite |
| 500-7 | 500 | 320 | 7 | 170~230 | Ferrite＋pearlite |
| 450-10 | 450 | 320 | 10 | 160~210 | Ferrite＋pearlite |
| 400-15 | 400 | 250 | 15 | 130~180 | Ferrite |
| 400-18 | 400 | 250 | 18 | 130~180 | Ferrite |
| 350-22 | 350 | 220 | 22 | ≤150 | Ferrite |
