ASTM A131 DH36 Shipbuilding Steel Coil
ASTM A131 DH36 Shipbuilding Steel Coil | High Strength & -20°C Toughness
Complete material data for ASTM A131 DH36 shipbuilding steel coil: chemical composition, mechanical properties, physical properties, equivalent grades, and applications in marine and offshore structures.
Hot rolling, controlled rolling, normalizing, thermo-mechanical control process (TMCP), welding, cutting, forming, machining
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ASTM A131 DH36 Shipbuilding Steel Coil Introduction
ASTM A131 DH36 is a high-strength hull structural steel with excellent low-temperature toughness, designated for shipbuilding and marine engineering under the ASTM A131/A131M standard. The 'D' indicates impact testing at -20°C, and the grade delivers a minimum yield strength of 355 MPa (51 ksi). This steel grade combines good weldability with reliable strength and ductility, making it suitable for critical structural components in ships, offshore platforms, and arctic environment vessels. It is typically supplied as hot-rolled coil, plate, or sections in normalized or controlled-rolled condition.
ASTM A131 DH36 Shipbuilding Steel Coil Chemical Composition
The chemical composition of ASTM A131 DH36 is designed to achieve high strength while maintaining good weldability and low-temperature toughness. Values are ladle analysis limits according to ASTM A131/A131M. Grain-refining elements (Nb, V, Ti, Al) are often added, controlled within specified maximums.
| Element | Standard Value (max or range) | Remarks |
|---|---|---|
| Carbon, C | 0.18 max | ladle analysis |
| Manganese, Mn | 0.90 – 1.60 | ladle analysis |
| Phosphorus, P | 0.035 max | ladle analysis |
| Sulfur, S | 0.035 max | ladle analysis |
| Silicon, Si | 0.10 – 0.50 | ladle analysis |
| Nickel, Ni | 0.40 max | residual |
| Chromium, Cr | 0.25 max | residual |
| Molybdenum, Mo | 0.08 max | residual |
| Copper, Cu | 0.35 max | residual |
| Niobium, Nb (Columbium) | 0.05 max | grain refiner (if added) |
| Vanadium, V | 0.10 max | grain refiner (if added) |
| Titanium, Ti | 0.02 max | grain refiner (if added) |
| Aluminum, Al total | 0.020 min (typically) | grain refiner; acid-soluble Al≥0.015% required |
| Nitrogen, N | 0.012 max (typical) | if not controlled by Ti/Al |
| Sum Nb+V+Ti | 0.12 max | if combination of grain refiners is used |
ASTM A131 DH36 Shipbuilding Steel Coil Thermal and Electrical Physical Properties
The following physical property data are typical for DH36 carbon-manganese structural steel at room temperature unless otherwise stated. These values are not specified in the standard but are derived from published data for similar compositions. They aid in design calculations for ship structures.
| Property | Typical Value | Unit | Test Condition / Remarks |
|---|---|---|---|
| Density, ρ | 7.85 | g/cm³ | at 20°C |
| Modulus of Elasticity, E | 200 – 210 | GPa | at room temperature |
| Shear Modulus, G | 80 – 82 | GPa | calculated from E and ν |
| Poisson's Ratio, ν | 0.29 – 0.31 | — | elastic range |
| Thermal Expansion Coefficient, α | 11.7 – 12.1 (average) | 10⁻⁶ / K | between 20°C and 100°C |
| Thermal Conductivity, λ | 51 – 54 | W/(m·K) | at 20°C |
| Specific Heat Capacity, c | 460 – 500 | J/(kg·K) | at 20°C |
| Electrical Resistivity, ρ_e | 0.19 – 0.22 | µΩ·m | at 20°C |
ASTM A131 DH36 Shipbuilding Steel Coil Mechanical Properties
Mechanical properties for ASTM A131 DH36 are determined in accordance with ASTM A370. Requirements apply to plates and coils supplied in the as-rolled, normalized, or TMCP condition. Impact tests are carried out on Charpy V-notch specimens at -20°C.
| Property | Standard Requirement | Unit | Test Condition / Remarks |
|---|---|---|---|
| Yield Strength, ReH (min) | 355 (51) | MPa (ksi) | transverse or longitudinal, as per specification |
| Tensile Strength, Rm | 490 – 620 (71 – 90) | MPa (ksi) | transverse or longitudinal |
| Elongation, A200 (min) | 21 | % | gauge length 200 mm (8 in) |
| Elongation, A50 (min) | 24 | % | gauge length 50 mm (2 in) |
| Bend Test (180°) | d=2a (t ≤ 25 mm) | — | no cracks; a=thickness |
| Bend Test (180°) | d=3a (t > 25 mm) | — | no cracks; a=thickness |
| Impact Energy, KV (longitudinal) | 27 avg / 20 single min | J | -20°C, Charpy V-notch, t ≤ 50 mm |
| Impact Energy, KV (transverse) | 20 avg / 14 single min | J | -20°C, Charpy V-notch, t ≤ 50 mm |
ASTM A131 DH36 Shipbuilding Steel Coil Fully Equivalent Material Standards and Substitutable Grades
| Country / Region | Standard / Society | Grade Designation | Remarks |
|---|---|---|---|
| USA (international) | ASTM A131/A131M | DH36 | Base standard |
| American Bureau of Shipping | ABS Rules | DH36 | Meets ABS Grade DH36 |
| Lloyd's Register | LR Rules | DH36 | Meets LR Grade DH36 |
| DNV (ex DNV GL) | DNV Rules | DH36 | Meets DNV Grade DH36 |
| Bureau Veritas | BV Rules | DH36 | Meets BV Grade DH36 |
| China Classification Society | CCS Rules | DH36 | Meets CCS Grade DH36 |
| ClassNK (Nippon Kaiji Kyokai) | NK Rules | DH36 | Meets NK Grade DH36 |
| Registro Italiano Navale | RINA Rules | DH36 | Meets RINA Grade DH36 |
| Korean Register | KR Rules | DH36 | Meets KR Grade DH36 |
| Germanischer Lloyd (now DNV) | GL Rules | DH36 | Historical, now part of DNV DH36 |
ASTM A131 DH36 Shipbuilding Steel Coil Application Introduction
ASTM A131 DH36 is primarily used in shipbuilding and marine construction where a combination of high strength and resistance to brittle fracture at low temperatures is required. The -20°C impact qualification makes it suitable for ships operating in cold climates. Typical applications include:
Product Applications: Ship hull plates and profiles, Deck plates and bulkhead structures, Stiffeners, keels, frames and girders, Offshore platform legs, braces and nodes, Caissons and conductors, Lifting and rigging structures
Processed into products: Main hull shell plates (bottom, side, strength deck), Transverse and longitudinal frames, Watertight bulkhead panels, Hatch coaming and side coaming, Deck stringer plates, Offshore wind tower flanges and connection rings, Padeyes and lifting lugs, Bracket and stiffener assemblies
Application industries: Shipbuilding (merchant ships, bulk carriers, container vessels, tankers), Offshore oil and gas structures (jack-up rigs, fixed platforms, FPSO hulls), Naval and defense (naval vessels, submarines secondary structures), Bridge construction (especially in low-temperature regions), Renewable energy (offshore wind turbine foundations, transition pieces), Heavy machinery and pressure vessels (when impact properties at sub-zero ambient temperatures are needed)
ASTM A131 DH36 Shipbuilding Steel Coil Similar / Closely Related Substitute Materials
| Country / Region | Standard / Society | Grade Designation | Remarks |
|---|---|---|---|
| USA (international) | ASTM A131/A131M | AH36 | Same strength, impact test at 0°C (A-grade toughness) |
| USA (international) | ASTM A131/A131M | EH36 | Same strength, impact test at -40°C (E-grade toughness) |
| USA (international) | ASTM A131/A131M | FH36 | Same strength, impact test at -60°C (F-grade toughness) |
| Europe | EN 10025-4 | S355ML | Thermo-mechanical ship steel, impact at -50°C (~EH36) |
| Europe | EN 10025-3 | S355NL | Normalized, impact at -50°C |
| China | GB/T 712 | DH36 | Same chemical/physical concept, sometimes tighter residual limits |
Notes:
Additional notes: DH36 can be supplied in normalized (N) or thermo-mechanical rolled (M) condition; the impact testing temperature is -20°C unless otherwise agreed.
- For thicknesses above 50 mm, mechanical property values may be slightly modified and are subject to agreement.
- Carbon equivalent (CEV) is usually controlled to max 0.38–0.40% for good weldability – verify with mill certificate.
- Z-direction through-thickness testing (Z-15, Z-25, Z-35) can be supplied when superior lamellar tearing resistance is required.
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