DH40 vs DH36
These two grades are listed as equivalents of each other: their chemistry windows overlap and they serve the same applications. They are not always identical — check the differences below before substituting, especially in certified designs.
DH40
Structural & HSLA Steel
DH40 pairs the 390 MPa strength of the 40-series hull steels with impact toughness certified at −20 °C. It is specified for hull zones and vessel types that see cold water or winter service, where AH40’s 0 °C guarantee is not enough.
Standards: AISI A131 DH40 · JIS KD40 (near) · GB DH40 (GB/T 712)
DH36
Structural & HSLA Steel
DH36 is the −20 °C impact version of the 355 MPa hull grade, specified for vessels trading in cold waters and for exposed structure where AH36 toughness is insufficient. Chemistry is the same family as AH36; the difference is the toughness guarantee and its verification.
Standards: AISI A131 DH36 · JIS KD36 (near) · GB DH36 (GB/T 712)
Chemical composition compared (%)
| Element | DH40 | DH36 |
|---|---|---|
| C | ≤0.18 | ≤0.18 |
| Si | ≤0.50 | ≤0.50 |
| Mn | 0.90–1.60 | 0.90–1.60 |
| P | ≤0.035 | ≤0.035 |
| S | ≤0.035 | ≤0.035 |
| Note | Nb/V/Ti grain-refining per class rules | Nb/V/Ti grain-refining per class rules |
Properties compared
| Property | DH40 | DH36 |
|---|---|---|
| Yield strength | ≥390 MPa | ≥355 MPa |
| Tensile strength | 510–660 MPa | 490–630 MPa |
| Impact | −20 °C, ≥41 J longitudinal (≤50 mm) | −20 °C, ≥34 J longitudinal (≤50 mm) |
| Density | 7.85 g/cm³ | 7.85 g/cm³ |
Sourcing either grade?
Nasteel stocks both families from Shenzhen with EN 10204 3.1 mill certificates by heat number.
Ask for a quotationSee full data sheets: DH40 · DH36. Substitution decisions for certified parts stay with the design authority.