What is ABS EQ70 Steel Plate?
ABS EQ70 is an ultra-high-strength marine steel approved by ABS (American Bureau of Shipping). ABS adopts a unified grade coding system for high-strength steel with yield strength exceeding 690 MPa:
- Q denotes the high-strength series; the prefix letter indicates the impact test temperature: AQ70 (0°C), DQ70 (-20°C), EQ70 (-40°C), FQ70 (-60°C);
- Number 70 corresponds to yield strength of 70 kgf/mm², approximately 690 MPa when converted to metric units, matching the strength grade of DNV E690.
We supply ABS EQ70 in two delivery conditions: conventional structural steel plates and lamellar tearing resistant (Z-direction property) steel plates (Z15/Z25/Z35). For thick plates applied to critical welded structures, stricter control is imposed on sulfur and phosphorus impurity contents. This steel grade is widely utilized in US-standard offshore projects, FPSO (Floating Production Storage and Offloading) modules and jack-up platform leg fabrication.
What is DNV E690 Steel Plate?
DNV E690 is a high-strength hull structural steel certified by DNV (the merged organization of Det Norske Veritas and Germanischer Lloyd). The suffix of the grade follows DNV's classification rules for temperature grades of marine steel:
- Letter E: Mandatory Charpy V-notch impact test at -40°C;
- Number 690: Specified minimum yield strength of 690 MPa.
This steel grade is primarily manufactured via quenched-and-tempered (QT) process coupled with grain-refined microalloying design to balance ultra-high strength and low-temperature toughness. It is developed specifically for Arctic-going vessels, load-bearing structures of offshore platforms and components of heavy-duty offshore cranes. All finished steel plates are subject to DNV mill inspection, and official classification society certification documents will be issued for shipbuilding delivery.
If you are preparing bids for offshore platform projects, Arctic vessel construction or offshore crane projects and feel uncertain about steel grade selection, kindly forward your project drawings, classification society specification requirements and plate thickness list to our engineering team. Our specialists will deliver a customized free steel grade selection proposal and cost-optimized quotation within 4 hours.
ABS EQ70 DNV E690 High Strength Marine Steel Plate Specification
| Item | Specification |
|---|---|
| Product Name | High Strength Marine Steel Plate |
| Available Grades | ABS EQ70, DNV E690 |
| Classification Standards | ABS Rules, DNV Rules |
| Steel Category | Quenched and Tempered High Strength Shipbuilding Steel |
| Thickness | 6–250 mm (Customized available) |
| Width | 1500–4000 mm |
| Length | 3000–18000 mm |
| Delivery State | Quenched and Tempered |
| Heat Treatment | Quenching + Tempering |
| Testing | Chemical Analysis, Tensile Test, Charpy Impact Test, Hardness Test, Ultrasonic Testing (Optional) |
| Surface Treatment | Shot Blasting, Primer Coating (Optional) |
| Cutting Service | CNC Cutting, Flame Cutting, Plasma Cutting |
| Applications | Container Ships, Bulk Carriers, Offshore Platforms, Marine Structures, Heavy-Duty Vessels |
ABS EQ70 vs DNV E690 Steel Plate Chemical Composition
| Element | DNV E690 General Plate | ABS EQ70 Conventional Plate | ABS EQ70 Z-direction Plate |
|---|---|---|---|
| C | ≤0.20 | ≤0.20 | ≤0.18 |
| Si | 0.10–0.55 | 0.10–0.55 | 0.10–0.50 |
| Mn | ≤1.70 | ≤1.70 | ≤1.65 |
| P | ≤0.030 | ≤0.030 | ≤0.020 |
| S | ≤0.030 | ≤0.030 | ≤0.010 |
| Als (Acid-soluble Al) | 0.015–0.080 | 0.015–0.080 | 0.020–0.080 |
| Nb | 0.02–0.05 | 0.02–0.05 | 0.02–0.05 |
| V | 0.04–0.10 | 0.04–0.10 | 0.04–0.10 |
| Ti | ≤0.02 | ≤0.02 | ≤0.02 |
| B | ≤0.005 | ≤0.005 | ≤0.005 |
Key difference: ABS EQ70 Z-direction structural plate significantly limits P and S content to suppress lamellar tearing during thick plate welding; DNV E690 has unified impurity index for conventional and Z-type plates without differentiated strict limits.
ABS EQ70 vs DNV E690 Steel Plate Mechanical Property
| Performance Index | DNV E690 | ABS EQ70 | Test Standard |
|---|---|---|---|
| Yield Strength (Re) | ≥690 MPa | ≥690 MPa | DNV Rule / ABS Rule |
| Tensile Strength (Rm) | 770–940 MPa | 770–940 MPa | Tensile test |
| Elongation (A) | ≥14% | ≥14% | Room temperature tensile |
| Charpy Impact (-40℃, Longitudinal) | ≥69 J | ≥62 J | Charpy V-notch |
| Charpy Impact (-40℃, Transverse) | ≥46 J | ≥41 J | Charpy V-notch |
| Z15 Reduction of Area | ≥15% | ≥15% | Z-direction tensile |
| Z25 Reduction of Area | ≥25% | ≥25% | Z-direction tensile |
| Z35 Reduction of Area | ≥35% | ≥35% | Z-direction tensile |
Core distinction: DNV E690 sets higher minimum impact energy acceptance value at -40℃, stricter toughness assessment, more suitable for ultra-low temperature Arctic working conditions.
Comparative Analysis of Low-Temperature Toughness: ABS EQ70 vs DNV E690 Plate
Consistency of Test Temperature
Both steel grades adopt -40°C as the certified Charpy impact temperature for Grade E / EQ, enabling reliable service in winter marine environments of North China Sea, North Atlantic Ocean and marginal Arctic waters. Moreover, both grades are available for upgrade to Grade F (-60°C) specification.
01
Margin of Impact Energy
DNV E690 features approximately 10% higher minimum longitudinal and transverse impact energy thresholds compared with ABS EQ70. Under identical plate thickness and heat-affected zone (HAZ) conditions after welding, E690 delivers superior resistance to brittle fracture under low-temperature impact loading.
02
Brittle Transition Temperature
The ductile-brittle transition temperature of DNV E690 is roughly 3–5°C lower than that of ABS EQ70, contributing to enhanced crack resistance under cyclic low-temperature loads acting on the ice belt structures of ship hulls.
03
Degradation Characteristic of Thick-Plate Mechanical Properties
Once plate thickness exceeds 100 mm, ABS EQ70 suffers faster deterioration of low-temperature toughness than DNV E690. Accordingly, DNV E690 holds prominent advantages for extra-heavy load-bearing steel plates with thickness over 100 mm.
04
ABS EQ70 vs DNV E690 High Strength Plate Weldability
Similarities in Welding Characteristics
Both grades are quenched-and-tempered (QT) ultra-high-strength steels featuring high carbon equivalent and cold cracking susceptibility index (Pcm). For thick plates, preheating before welding, interpass temperature control and post-weld heat treatment (PWHT) are mandatory requirements:
- Recommended preheating temperature: 120–180°C for plate thickness exceeding 25 mm;
- Interpass temperature shall be controlled within 150–200°C;
- Post-weld stress relief annealing: Soaking at 550–620°C, with a soaking duration of 1–2 hours per 25 mm of plate thickness.
Common welding processes: SMAW (Shielded Metal Arc Welding), GMAW (Gas Metal Arc Welding), FCAW (Flux-Cored Arc Welding), as well as SAW (Submerged Arc Welding) for longitudinal butt splicing of hull plates.
Differences in Welding Performance
1. Toughness Stability of Heat-Affected Zone (HAZ)
DNV E690 steel adopts mature grain-refined microalloying technology, leading to limited toughness deterioration in the welding heat-affected zone and a higher pass rate for post-weld Charpy impact tests.
2. Z-Direction Welding Adaptability
ABS EQ70 steel with low sulfur (S) and low phosphorus (P) composition delivers prominent advantages for full penetration welding of T-joints, which can effectively prevent lamellar tearing at the weld root.
3. Certified Welding Procedure Specification (WPS)
Projects under DNV classification must adopt DNV-approved WPS for E690 steel; vessels classified by ABS shall use ABS-certified welding procedures for EQ70 steel. Cross-grade application of WPS requires re-conduction of welding procedure qualification.
Typical Application Scenarios: ABS EQ70 vs DNV E690 Marine Steel Plate
Main Applications of ABS EQ70
- Load-bearing support structures for ABS-classed FPSO (Floating Production Storage and Offloading units)
- Cantilever beams and jacking mechanisms of American-standard jack-up offshore platforms
- Offshore modules exported to North America and South America
- Thick-plate welded structures requiring lamellar tearing resistance (customizable Z-grade: Z15/Z25/Z35)
Main Applications of DNV E690
- Ice belt outer hull plating and ice-reinforced structural members of Arctic icebreakers
- Main leg plates for DNV-classed offshore drilling platforms and jack-up rigs
- Primary load-bearing girders and boom structural plates of heavy-lift crane vessels
- Critical structural steel for offshore wind installation vessels owned by European shipowners
Material Selection Guideline: ABS EQ70 vs DNV E690
When to select ABS EQ70
✅ The project requires ABS classification society certification;
✅ Extensive thick-plate full penetration welded structures demanding Z-direction tear resistance;
✅ Project delivery targeted at offshore markets such as the United States, Brazil and Mexico;
✅ Cost control is required while basic low-temperature toughness requirements are satisfied.
When to select DNV E690
✅ The vessel or offshore platform requires formal certification from DNV GL;
✅ Long-term service in ambient temperatures below -30°C or Arctic shipping routes;
✅ Extra-thick high-strength load-bearing structural members with plate thickness over 100 mm;
✅ High margin requirement for base metal low-temperature Charpy impact toughness.
Substitution Principle
For mechanical equipment free of classification society certification, DNV E690 and ABS EQ70 can be mutually substituted subject to matching strength properties. For shipbuilding projects involving cross-class certification, formal approval from the relevant classification society shall be obtained prior to any material substitution.
Supply Service from GNEE Steel
As a professional marine high-strength steel supplier with 18 years of export experience, GNEE Steel provides one-stop supporting service for DNV E690 and ABS EQ70 steel plates to solve the pain points of marine engineering procurement:
Diversified Product Customization
Supply conventional hot rolled plate, Z-direction anti-tear plate (Z15/Z25/Z35), ultra-thick plate (6–300mm), fixed-size cutting plate; provide TMCP and QT two delivery state steel according to customer process requirements.
Deep Processing Service
Plate flame cutting, plasma cutting, CNC blanking, edge chamfering, shot blasting + marine anti-rust primer coating processing to realize factory direct delivery of finished structural parts.
Spot & Customized Rolling Delivery
Large inventory of conventional specification E690 and EQ70 steel for urgent order delivery within 7 working days; customized special thickness, width, length steel plate rolling with stable delivery cycle of 30–45 days.
New customers enjoy a 3% discount for first order of marine high-strength steel plates, free CNC cutting sample service for verification before bulk order, contact our overseas sales manager right now to lock in spot inventory and favorable price.
FAQ
Can ABS EQ70 and DNV E690 be used interchangeably on ships?
Yes, ABS EQ70 and DNV E690 are technically equivalent extra-high strength structural steel grades, but they cannot be swapped without proper class approval. Both share a minimum yield strength of 690 MPa and identical low-temperature impact testing standards at –40°C (indicated by 'E' in DNV and 'EQ' in ABS).
What is the difference between EQ70 F grade and E grade?
The difference between EQ70 (Grade E) and F grade (FQ70) marine structural steel lies strictly in their Charpy V-notch impact test temperatures, with Grade E tested at -40°C and Grade F tested at -60°C. Both share the same minimum yield strength of 690 MPa (100 ksi) and are quenched and tempered high-strength steels used for offshore platforms and shipbuilding.
Does DNV E690 support Z-direction lamellar tearing resistant customization?
Yes, DNV E690 (an extra high-strength extra-high-yield structural steel used in shipbuilding and offshore platforms) fully supports Z-direction lamellar tearing-resistant customization.
Are both DNV E690 steel and ABS EQ70 steel suitable for outdoor cold region construction in winter?
Yes, both DNV E690 steel and ABS EQ70 steel are highly suitable for outdoor cold region construction in winter, as both carry an "E" grade designation meaning their Charpy V-notch impact toughness is officially certified down to -40°C and both feature a high minimum yield strength of 690 MPa.
