ABS EQ51 Steel Plate
ABS EQ51 is an ultra-high strength marine steel plate certified by the American Bureau of Shipping (ABS). It is manufactured via quenching and tempering (Q+T) or thermo-mechanical controlled rolling (TMCP), complying with the ABS Rules for Steel Vessels and marine steel standard ASTM A131/A131M.
Grade Designation Definition
E: Mandatory Charpy V-notch impact test at -40°C to guarantee low-temperature brittle fracture resistance;
Q: Quenched & Tempered delivery condition for ultra-high strength marine steel;
51: Nominal minimum yield strength of 500 MPa (73 ksi).
Main available thickness range: 6 mm–300 mm, maximum custom width up to 4850 mm. Cut-to-length processing is available according to the dimensions of structural components. Certification for Z-direction lamellar tearing resistance (Z15/Z25/Z35) can be provided for tubular joints and heavy-gauge high-load welded joints.
DNV E500 (NV E500) Steel Plate
DNV E500 is a high-strength offshore structural steel approved by Det Norske Veritas (DNV), conforming to offshore steel structure specification DNV-OS-B101.
Grade Designation Definition
E: Requires -40°C low-temperature impact property, consistent with ABS Grade E series steel;
500: Clearly specified minimum yield strength of 500 MPa for straightforward engineering calculation.
This grade is the direct equivalent of ABS EQ51 within the DNV certification system, with identical production process options (TMCP / Q+T / normalizing). It serves as the preferred structural material for new construction and refurbishment of offshore platforms requiring DNV classification certification in Europe, Norway and Southeast Asia.
ABS EQ51 and DNV E500 High Strength Shipbuilding Steel Plate Specification
| Item | Specification |
|---|---|
| Product Name | High Strength Shipbuilding Steel Plate |
| Available Grades | ABS EQ51, DNV E500 |
| Classification Standards | ABS, DNV |
| Steel Category | High Strength Marine Structural Steel |
| Manufacturing Process | TMCP (Thermo-Mechanical Controlled Processing) or Quenched & Tempered |
| Thickness | 6–300 mm |
| Width | 1500–4850 mm |
| Length | 3000–18000 mm |
| Delivery Condition | TMCP / Q+T |
| Surface Finish | Natural Mill Surface, Shot Blasted, Shop Primer (Optional) |
| Inspection | Chemical Analysis, Tensile Test, Charpy Impact Test, Ultrasonic Testing (Optional), Dimensional Inspection |
| Certification | Mill Test Certificate (EN 10204 3.1), ABS or DNV Classification Approval (as required) |
| Processing Service | CNC Cutting, Flame Cutting, Plasma Cutting, Beveling |
ABS EQ51 and DNV E500 High Strength Steel Plate Chemical Composition
| Element | ABS EQ51 Max Content | DNV E500 Max Content |
|---|---|---|
| C | 0.20% | 0.20% |
| Si | 0.55% | 0.55% |
| Mn | 1.70% | 1.70% |
| P | 0.030% | 0.030% |
| S | 0.030% | 0.030% |
| N | 0.020% | 0.020% |
| Al (Min.) | 0.018% | 0.018% |
| Nb | 0.06% | 0.06% |
| V | 0.12% | 0.12% |
| Ti | 0.05% | 0.05% |
| Cr | 1.50% | 1.50% |
| Mo | 0.70% | 0.70% |
| Ni | 3.50% | 3.50% |
| Cu | 0.55% | 0.55% |
ABS EQ51 and DNV E500 High Strength Steel Plate Mechanical Property
| Mechanical Index | ABS EQ51 Standard Value | DNV E500 Standard Value |
|---|---|---|
| Minimum Yield Strength (ReH) | 500 MPa | 500 MPa |
| Tensile Strength (Rm) | 610–770 MPa | 610–770 MPa |
| Minimum Elongation (A₅) | 16% | 16% |
| Delivery State | Q+T / TMCP / N | Q+T / TMCP / N |
| Maximum Available Thickness | 300mm | 250mm |
ABS EQ51 and DNV E500 Shipbuilding Steel Plate Weldability Characteristics
ABS EQ51 and DNV E500 share identical welding performance thanks to their matched alloy composition and carbon equivalent.
Overall Weldability
Low carbon equivalent reduces hardening tendency in the heat-affected zone (HAZ). Preheating temperatures are recommended as follows to avoid hydrogen-induced cold cracking:
- Plate thickness ≤ 50 mm: 80°C
- 50 mm ＜ Thickness ≤ 150 mm: 100–120°C
- Thickness ＞ 150 mm: 130–150°C
Applicable Welding Processes
Compatible with SMAW (Shielded Metal Arc Welding), FCAW (Flux-Cored Arc Welding with CO₂ shielding), SAW (Submerged Arc Welding) and GMAW (Gas Metal Arc Welding). To achieve matched mechanical properties for welded joints, matching high-strength low-temperature welding consumables shall be adopted (550 MPa yield strength grade with certified Charpy impact toughness at -40°C).
Post-Weld Heat Treatment (PWHT)
PWHT can be performed optionally for general structural members. Mandatory PWHT (tempering at 580–620°C) is required for tubular joints and load-bearing nodal connections of drilling platforms to relieve welding residual stress.
ABS EQ51 and DNV E500 Plate Corrosion Resistance and Fatigue Performance
Marine Corrosion Resistance
Both ABS EQ51 and DNV E500 steel plates are manufactured with stringent control over detrimental impurities such as sulfur (S) and phosphorus (P), with trace copper (Cu) alloying addition to retard atmospheric corrosion under salt fog conditions.
- Base Material Performance: No remarkable performance difference exists between the two grades regarding salt spray corrosion in the marine splash zone and electrochemical corrosion in the tidal zone.
- Limitation Note: Neither ABS EQ51 nor DNV E500 qualifies as weathering steel or corrosion-resistant alloy steel. For long-term service in marine environments, a full marine anti-corrosion coating system (epoxy primer + intermediate coat + topcoat) is mandatory, or cathodic protection shall be implemented for subsea structural components.
- Z-Direction Performance Option: Steel plates certified to Z15/Z25/Z35 specifications effectively prevent lamellar tearing at welded joints induced by the combined effect of cyclic marine stress and corrosion, which is a mandatory technical requirement for tubular joint structural steel applied to FPSO (Floating Production Storage and Offloading Units).
Fatigue Performance
ABS EQ51 and DNV E500 deliver identical fatigue limits: under cyclic loading of 2×10⁶ cycles, the fatigue strength limit of both grades reaches approximately 260 MPa. They are applicable to marine crane pedestals, longitudinal hull girders and hoisting structures of drilling platforms subjected to long-term cyclic wave loads. Surface grinding treatment at weld toes can further extend fatigue life by 20%–30%. Provided equivalent surface finishing and welding quality, no distinguishable performance gap can be found between the two steel grades.
ABS EQ51 and DNV E500 High Strength Plate Typical Application Scenarios
ABS EQ51 Main Application
- Container ship hatch coaming, polar vessel hull and deck structure;
- ABS-classified jack-up offshore drilling platforms, MODU mobile offshore drilling units, platform cantilever beam and leg rack structure;
- Marine heavy lifting cranes, offshore wind power installation ships for American and Middle East marine projects;
- Offshore auxiliary vessels, floating dock key load-bearing structural components requiring ABS certification filing.
DNV E500 Main Application
- North Sea offshore oil & gas platforms, Norwegian coastal marine engineering facilities (mandatory DNV certification);
- DNV-classed FPSO, FPU floating production units, subsea module support frame;
- European shipyard-built heavy-lift vessels, offshore wind foundation steel structure;
- Marine projects in Southeast Asia and Australia with DNV classification society supervision requirements.
One-Stop Supply from GNEE Steel
With 18 years of professional marine high-strength steel export experience, GNEE Steel has passed ISO9001 quality system, CE product certification, ABS/DNV nine major classification society mill factory certification, with 7 domestic warehouses, exported to more than 60 countries worldwide, serving top shipyards and offshore EPC contractors globally. We provide full-cycle technical and processing services for ABS EQ51 and DNV E500 plates:
Custom Physical & NDT Testing Service
Standard test: Room-temperature tensile, -40℃ Charpy impact, chemical composition spectral analysis;
Optional enhanced inspection: Z15/Z25/Z35 Z-direction tensile test, full-plate UT ultrasonic flaw detection (level I/II), CTOD crack tip opening displacement test, SGS third-party inspection witness;
Test reports attached to delivery documents for direct classification society filing.
Deep Processing Value-Added Service
CNC flame/plasma cutting, plate bending, edge milling, shot blasting rust removal, marine anti-corrosion primer pre-coating, fixed-size blanking according to customer drawing requirements, reducing on-site processing workload for shipyards.
Professional Technical After-Sales Support
Marine steel welding engineer team provides free welding procedure parameter guidance, thick plate preheating & PWHT process suggestions, material grade replacement technical demonstration documents.
Send your project drawing, classification society requirement, thickness dimension demand to GNEE technical team now, we will provide free technical comparison sheet of ABS EQ51 vs DNV E500 + accurate quotation + stock availability report within 2 working hours, support L/C letter of credit settlement for overseas project procurement.
Send your project drawing, classification society requirement, thickness dimension
FAQ
Is ABS EQ51 equivalent to DNV E500?
Yes, ABS EQ51 is equivalent to DNV E500. Both are ultra-high-strength structural and shipbuilding steel grades with matching core mechanical requirements.
Can DNV E500 replace ABS EQ51?
Yes, DNV E500 (NV E500) can generally replace ABS EQ51 (AB/EQ51) because they are equivalent ultra-high-strength hull structural steel grades defined by different classification societies. Both specify a minimum yield strength of 500 MPa and identical impact test temperature requirements (-40°C for 'E'/'EQ' grades).
What is the difference between ABS and DNV classification?
ABS (American Bureau of Shipping) and DNV (Det Norske Veritas) differ primarily in their regional origins, technical focus, and engineering methodologies. ABS is US-based with a strong focus on practical compliance and traditional offshore oil and gas sectors, while DNV is European-based (Norwegian-German) and emphasizes risk-based design, digital solutions, and environmental sustainability.
What is the yield strength of EQ51 steel?
The minimum yield strength of EQ51 steel (such as ABS Grade EQ51) is 500 MPa (megapascals), which is equal to 73 ksi (kilopounds per square inch).
