DNV D620 and DNV D690 are grades of high-strength, low-alloy (HSLA) shipbuilding/marine structural steel, with the main difference being their strength level: DNV D690 offers higher yield and tensile strength (around 690 MPa) than DNV D620 (around 620 MPa), making D690 suitable for more demanding offshore/ship structures needing superior strength, while both offer good toughness for marine environments.
Chemical composition of Heat analysis for Shipbuilding steel plate NV D620 (Max %):
|
C |
Si |
Mn |
P |
S |
Al |
N |
|
0.20 |
0.10-0.55 |
1.7 |
0.030 |
0.030 |
0.015-0.08 |
0.02 |
|
Ni |
V |
Ti |
Cu |
B |
Nb |
Mo |
|
|
0.04-0.10 |
0.02 |
|
0.005 |
0.02-0.05 |
|
Chemical composition for DNV Grade D690 ship steel (Heat Analysis Max%)
| Main chemical elements composition of DNV Grade D690 | |||||
| C | Si | Mn | P | S | N |
| 0.20 | 0.55 | 1.70 | 0.030 | 0.030 | 0.02 |
Mechanical properties for Shipbuilding steel plate DNV D620:
|
Yield strength (Mpa) |
Tensile strength (Mpa) |
Steel Mark |
|
620 |
720-890 |
NV D620 |
Mechnical property for DNV Grade D690 shipbuilding structual steel:
| Yield strength (≥Mpa) | Tensile strength (Mpa) | Impacting test |
| 690 | 770-940 | |
| -20 Centigrade |
Strength: D690 signifies a minimum yield strength of approximately 690 MPa (megapascals), whereas D620 has a minimum yield strength around 620 MPa.
Applications: Both are used in marine engineering, but D690's higher strength suits heavier-duty structural components for ocean platforms, naval ships, and pipelines, while D620 serves similar, slightly less intensive, structural roles.
Standards: They fall under the Det Norske Veritas (DNV) classification for marine steel, with 'D' indicating a specific heat treatment (Quenched & Tempered - QT) and '620'/'690' denoting their strength class.
In essence, D690 is a stronger variant of D620, designed for higher stress applications in harsh marine conditions.
