DNV D32 Shipbuilding Steel Coil
DNV D32 Shipbuilding Steel Coil – High Toughness Marine Structural Plate
Comprehensive material data for DNV D32 shipbuilding steel coil: chemical composition, mechanical properties, thermal properties, international equivalents, and applications.
Thermomechanical rolling (TMCP), normalizing, welding, cutting, bending, forming
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DNV D32 Shipbuilding Steel Coil Introduction
DNV D32 is a high-strength shipbuilding structural steel defined by the DNV GL classification society rules. It belongs to the normal and high-strength steels for hull structures, designated by the minimum yield strength of 315 MPa and guaranteed impact toughness at -20°C (D-grade). This grade is characterized by good weldability, excellent low-temperature toughness, and high strength-to-weight ratio, making it suitable for critical ship components.
- Minimum yield strength: 315 MPa
- Tensile strength range: 440–590 MPa
- Impact energy at -20°C: ≥31 J (longitudinal)
- Fine grain practice with controlled alloying for improved toughness
The material is typically supplied as coils or plates in normalized or thermomechanical rolled condition, meeting the requirements of IACS UR W11 and recognized by all major classification societies.
DNV D32 Shipbuilding Steel Coil Chemical Composition
The chemical requirements for D32 grade are in accordance with IACS UR W11 and DNVGL rules. Carbon content is strictly limited to ensure good weldability. Manganese contributes to strength and toughness. Fine grain practice is achieved by sufficient aluminium content and optional microalloying with Nb, V or Ti. Maximum and minimum limits are as shown.
| Element | Standard Requirement (wt%) | Remarks |
|---|---|---|
| Carbon (C) | ≤0.18 | Max |
| Manganese (Mn) | 0.90–1.60 | Range |
| Silicon (Si) | ≤0.50 | Max |
| Phosphorus (P) | ≤0.035 | Max |
| Sulfur (S) | ≤0.035 | Max |
| Aluminium (Al, acid soluble) | ≥0.015 | Min, as grain refiner |
| Niobium (Nb) | 0.02–0.05 | Optional, if added |
| Vanadium (V) | 0.05–0.10 | Optional, if added |
| Titanium (Ti) | ≤0.02 | Optional, if added |
DNV D32 Shipbuilding Steel Coil Thermophysical and Electrical Properties
The following values are typical for normalized/thermomechanical rolled C-Mn shipbuilding steel and are not mandatory requirements of the DNV standard. They are provided as engineering reference data for design and thermal analysis.
| Property | Typical Value | Unit | Test Condition / Remarks |
|---|---|---|---|
| Density (ρ) | 7850 | kg/m³ | At 20°C |
| Elastic modulus (E) | 210 | GPa | At room temperature |
| Shear modulus (G) | 80 | GPa | At room temperature |
| Poisson's ratio (ν) | 0.30 | – | Elastic range |
| Thermal expansion coefficient (α) | 12.0 | 10⁻⁶ /K | 20–100°C |
| Thermal conductivity (λ) | 50 | W/(m·K) | At 20°C |
| Specific heat capacity | 460 | J/(kg·K) | At 20°C |
| Electrical resistivity (ρₑ) | 0.16 | 10⁻⁶ Ω·m | At 20°C |
DNV D32 Shipbuilding Steel Coil Mechanical Properties
Mechanical properties are specified according to DNVGL rules. Tensile testing is performed on transverse or longitudinal specimens as required. Impact tests are conducted on Charpy V-notch specimens at -20°C. For thicknesses ≤50 mm, the requirements are listed below; for greater thicknesses the values may be modified subject to agreement. Bending test with 180° angle and specified former diameter applies.
| Property | Standard Requirement | Unit | Test Condition |
|---|---|---|---|
| Yield strength (ReH) | ≥315 | MPa | Transverse, t ≤50 mm |
| Tensile strength (Rm) | 440–590 | MPa | Transverse, t ≤50 mm |
| Elongation after fracture (A) | ≥22 | % | Gauge length 5.65√So, transverse, t ≤50 mm |
| Bending test – former diameter | 3a (a = specimen thickness) | – | 180° bending, t ≤50 mm |
| Charpy impact energy (KV, longitudinal) | ≥31 | J | -20°C, t ≤50 mm |
| Charpy impact energy (KV, transverse) | ≥22 | J | -20°C, t ≤50 mm (if required) |
DNV D32 Shipbuilding Steel Coil Equivalent Standards and Fully Matched Substitute Grades
| Country/Region | Standard/Society | Grade | Remarks |
|---|---|---|---|
| International | IACS UR W11 | D32 | Basis for all classification society grades |
| USA | ABS | D32 | ABS Rules, identical to IACS |
| France | BV | D32 | Bureau Veritas Rules |
| China | CCS | D32 | China Classification Society Rules |
| South Korea | KR | D32 | Korean Register Rules |
| United Kingdom | LR | D32 | Lloyd's Register Rules |
| Japan | NK | D32 | Nippon Kaiji Kyokai Rules |
| Italy | RINA | D32 | RINA Rules |
DNV D32 Shipbuilding Steel Coil Application Introduction
DNV D32 steel coil is widely used in shipbuilding and marine engineering due to its balanced strength and toughness. It can be processed by cutting, cold and hot forming, welding, and surface treatment. Typical products and components include:
Product Applications: Cargo ships, bulk carriers, tankers, container vessels, Offshore platform decks and modules, Floating production storage and offloading (FPSO) units, Bridge and lock gate structures, Wind turbine foundation transition pieces (marine)
Processed into products: Hull bottom and side plates, Main deck and stringer plates, Transverse and longitudinal bulkheads, Web frames, stiffeners, and brackets, Hatch coamings and side girders, Offshore structural beams and columns
Application industries: Shipbuilding and ship repair, Offshore oil and gas platforms, Marine and coastal structures, Heavy engineering and structural fabrication
DNV D32 Shipbuilding Steel Coil Near-Equivalent and Similar Substitute Materials
| Country/Region | Standard/Grade | Grade | Remarks |
|---|---|---|---|
| International | IACS UR W11 | AH32 | Impact test at 0°C, otherwise similar strength |
| International | IACS UR W11 | EH32 | Impact test at -40°C, higher toughness requirement |
| International | IACS UR W11 | D36 | Higher strength (min ReH 355 MPa), same impact temperature |
| International | IACS UR W11 | A/D (normal strength) | Ordinary strength ship steel; D is for -20°C impact, lower yield strength (235 MPa) |
Notes:
- Z-grade through-thickness property (Z35, Z25) can be specified for improved lamellar tearing resistance.
- For thickness >50 mm, reduced mechanical properties may be agreed case-by-case; minimum impact energy values may also be modified.
- Weldability: preheat may be necessary for thick sections or high restrained joints, but generally good as-rolled properties allow welding without post-weld heat treatment.
- Surface condition: normally supplied as descaled, oiled or primer painted if requested.
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