AH40 High Strength Hull Shipbuilding Steel Plate for Marine & Offshore Projects

  IACS Certified 390 MPa Yield Strength Steel with 0°C Impact Toughness  

Overview

The designation AH40 originates from the International Association of Classification Societies (IACS) system. It is not merely a Chinese steel grade, but a universal specification implemented by classification societies and steel mills worldwide. It is an internationally recognized material specification that ensures global consistency in material performance, certification, and acceptance standards for shipbuilding and offshore engineering.

This steel grade is specifically designed for ship hull structures requiring excellent weldability and high strength. Its core performance is characterized by a minimum yield strength of 390 MPa and reliable impact toughness at 0°C, making it an ideal choice for constructing vessels navigating temperate and warm climate waters, especially for high-stress areas.

Definition and Naming Logic

The designation AH40 originates from the International Association of Classification Societies (IACS) Unified Requirements.

Its logical structure is: 1 letter + 1 letter + 2 digits

First letter (A): Quality grade symbol, representing its impact toughness test temperature at 0°C.
Second letter (H): Strength grade symbol, denoting it as High Strength steel.
Digits (40): Minimum yield strength identifier, in units of 40kgf/mm²（390 MPa）.

Code Interpretation

Therefore, when treating AH40 as a code, the correct and complete deciphering is:

"A high-strength shipbuilding structural steel requiring impact testing at 0°C, with a minimum yield strength of 390 MPa."

Value Proposition

Just like the karat standard for gold, the AH40 specification provides the simplest and most reliable common benchmark for complex international procurement. As professional Chinese suppliers, we create our core value by delivering this globally-endorsed quality with optimal cost efficiency and reliable service.

We are a Chinese supplier offering AH40 in spot supply and mill-direct ordering services, with full export service capabilities.

We have served global shipyards and are familiar with classification society inspection processes.

Start Your AH40 Procurement

We provide two procurement options for AH40 steel plates, so you can choose the most cost-effective solution for your project. Backed by competitive prices, strict quality control, and on-time delivery, we make sourcing simple and reliable.

✓ Immediate availability & pricing

✓ Formal quotation in 8 hours

Supply-Available AH40 Ship Plates and Approved Classification Societies 

AH40 steel plates are certified and approved by all major international classification societies, ensuring global acceptance for marine construction projects. The following ranking is in alphabetical order of the classification society abbreviations.

ABS

American Bureau of Shipping

United States

✓ Available
Certified
BV

Bureau Veritas

France

✓ Available
Certified
CCS

China Classification Society

China

✓ Available
Certified
CRS

Croatian Register of Shipping

Croatia

Certified
DNV

Det Norske Veritas  (DNV & GL)

Norway

✓ Available
Certified
IRS

Indian Register of Shipping

India

Certified
KR

Korean Register of Shipping

South Korea

✓ Available
Certified
LR

Lloyd's Register

United Kingdom

✓ Available
Certified
NK

ClassNK

Japan

✓ Available
Certified
PRS

Polish Register of Shipping

Poland

Certified
RINA

Registro Italiano Navale

Italy

✓ Available
Certified
RS

Russian Maritime Register of Shipping

Russia

✓ Available
Certified

Note: In practical applications and certification documents, AH40 is typically prefixed with the specific classification society abbreviation to indicate compliance with that society's specific rules and approval requirements. For example, CCS AH40 (China Classification Society), ABS AH40 (American Bureau of Shipping), BV AH40 (Bureau Veritas), and DNV AH40 (Det Norske Veritas). The exception is the Russian Maritime Register of Shipping (RS), where the steel grade is designated as PC AH40.

Key Advantages of AH40 Steel Grade

Steel Grade
High Strength Performance
Standard Temperature Toughness
Marine Durability
Excellent Fabrication Properties
AH40 Marine Steel 390 MPa minimum yield strength provides optimal balance of high strength and cost-effectiveness for demanding marine applications and high-stress areas. Maintains stable impact toughness at 0°C for reliable standard climate performance in high-strength structures. Specifically designed for high-strength areas of large vessels operating in temperate waters and demanding marine environments. Superior weldability and formability for efficient shipyard fabrication of high-strength components.

Chemical Composition & Mechanical Properties of AH40 Steel

Chemical Composition (Typical, %)

C Si Mn P S Cu Cr Ni Nb V Ti Mo N Al
≤0.18 ≤0.50 0.90 – 1.60 ≤0.035 ≤0.035 ≤0.35 ≤0.20 ≤0.40 0.02 – 0.05 0.05 – 0.10 ≤0.02 ≤0.08 - ≥0.015

i Chemical Element Explanations

C (Carbon): ≤0.18% - Influences strength and hardness.
Si (Silicon): ≤0.50% - Increases strength, deoxidizer.
Mn (Manganese): 0.90-1.60% - Enhances strength and toughness, desulfurizer.
P (Phosphorus): ≤0.035% - Harmful element, reduces toughness.
S (Sulfur): ≤0.035% - Harmful element, causes hot shortness.
Cu (Copper): ≤0.35% - Improves corrosion resistance.
Cr (Chromium): ≤0.20% - Improves corrosion resistance and hardness.
Ni (Nickel): ≤0.40% - Enhances toughness and low-temperature properties.
Nb (Niobium): 0.02-0.05% - Refines grain structure, improves strength.
V (Vanadium): 0.05-0.10% - Refines grain structure, improves toughness.
Ti (Titanium): ≤0.02% - Refines grain, fixes carbon and nitrogen.
Mo (Molybdenum): ≤0.08% - Improves high-temperature strength and corrosion resistance.
N (Nitrogen): - (Controlled by production process)
Al (Aluminum): ≥0.015% - Deoxidizer, refines grain structure.

* Typical values according to classification society specifications. Actual limits may vary by approval.

Mechanical Properties of AH40 Steel

Thickness (mm) Yield Strength (MPa) Tensile Strength (MPa) Elongation (%) Impact Test Temperature Longitudinal Impact (KV2)/J Transverse Impact (KV2)/J
≤50 mm ≥390 MPa 510 – 660 MPa ≥20% 0°C 41 27
>50~70 mm ≥390 MPa 510 – 660 MPa ≥20% 0°C 48 31
>70~150 mm ≥390 MPa 510 – 660 MPa ≥20% 0°C 55 37

A-Grade Hull Steel: Strength Grade Comparison for Marine Applications

The following table compares different strength grades within the A-Grade hull steel series (all grades impact tested at 0°C), illustrating available options for increasing load-bearing capacity while maintaining the same 0°C impact toughness.

Comparison of A-Grade Marine Steel Plates for Shipbuilding Applications
Steel Grade Impact Test Temperature Yield Strength (Minimum) Typical Application Environment
AH32 0°C ≥ 315 MPa Primary structures for coastal vessels and non-exposed structures of ocean-going ships in temperate zones.
AH36 0°C ≥ 355 MPa Primary structures for vessels in warm to temperate waters; higher strength requirement applications.
AH40 0°C ≥ 390 MPa Key high-stress areas on large vessels in non-polar regions (e.g., hatch corners, strength decks).

40-Class Hull Steel: Quality Grade Comparison for Different Temperature Requirements

This table compares different quality grades within the 40 Class high-strength hull steel series. All grades share the same minimum yield strength (≥390 MPa) but are designed for different service temperatures and marine environments.

Comparison of 40-Class Steel Quality Grades for Different Marine Service Temperatures
Quality Grade Steel Grade Yield Strength (Minimum) Impact Test Temperature Key Selection Insight
 Standard Temperature AH40 ≥ 390 MPa 0°C Cost-effective high strength for standard temperature marine applications.
Low-Temperature DH40 ≥ 390 MPa -20°C Same strength as AH40 but with -20°C toughness for cold climate operations.
Enhanced Low-Temperature EH40 ≥ 390 MPa -40°C Primary high-strength steel for global ocean-going vessels requiring Arctic service capability.

Choose Your Optimal Marine Steel Grade

Compare key specifications across similar grades. Varying parameters are highlighted for quick decision-making.

AH32

STANDARD
Impact Test
0°C ≥31J
Tensile Strength 440-570 MPa
Yield Strength (Min) ≥315 MPa
Key Feature Cost-Effective

AH36

HIGHER STRENGTH
Impact Test
0°C ≥34J
Tensile Strength 490-630 MPa
Yield Strength (Min) ≥355 MPa
Key Feature Higher Strength

AH40

CURRENT
Impact Test
0°C ≥41J
Tensile Strength 510-660 MPa
Yield Strength (Min) ≥390 MPa
Key Feature Maximum Strength

DH32

LOW TEMP
Impact Test
-20°C ≥31J
Tensile Strength 440-570 MPa
Yield Strength (Min) ≥315 MPa
Key Feature Cold Climate

EH32

ARCTIC
Impact Test
-40°C ≥31J
Tensile Strength 440-570 MPa
Yield Strength (Min) ≥315 MPa
Key Feature Arctic Service

FH32

SUPER LOW
Impact Test
-60°C ≥31J
Tensile Strength 440-570 MPa
Yield Strength (Min) ≥315 MPa
Key Feature Extreme Cold

Typical Applications of AH40 Marine Steel Plate

High Strength Hull Structures
AH40 steel plates are a primary choice for constructing the high-stress areas of main hull structures in large ocean-going vessels. Their 390 MPa minimum yield strength allows for significant weight reduction and increased cargo capacity while ensuring structural integrity under demanding loads.
Strength Decks & Bulkheads
For strength decks and watertight bulkheads requiring higher load capacity, AH40 provides an excellent balance of high strength and good weldability. This makes it ideal for critical structural elements in modern ship design, optimizing plate thickness and overall weight.
Critical Structural Components
Key load-bearing elements such as hatch coamings, longitudinal stiffeners, and bilge keels are fabricated from AH40. Its guaranteed 390 MPa yield strength and enhanced toughness ensure reliability in the most demanding areas of a vessel's structure.
Large Vessel Optimization
The use of AH40 high-strength steel is critical for the economic viability of large container ships, bulk carriers, and tankers. Its higher allowable stress enables the use of thinner plates, resulting in significant weight savings, improved fuel efficiency, and increased deadweight tonnage.
Offshore & Port Equipment
Heavy lift cranes, ship-to-shore container gantries, and components for offshore platforms benefit from the high strength of AH40. Its superior mechanical properties allow for the design of lighter, more efficient equipment capable of handling extreme loads.

Available Sizes & Supply Conditions for AH40 Steel Plate

Dimensions

Thickness: 6 – 150 mm

Width: Up to 5,300 mm

Length: Up to 18,000 mm

Supply Conditions

Delivery Condition: Normalized (N) / Thermo-Mechanical Control Processed (TMCP) / Quenched and Tempered (QT) for thicker grades
Standards: ASTM A131, EN 10025-3, JIS G3106, GB/T 712

Quality Control & Certification for AH40 Marine Steel

Inspection & Quality Control

• Chemical composition analysis and verification
• Tensile and elongation testing for mechanical properties
• Charpy V-notch impact testing at 0°C for toughness verification (higher energy requirements than AH32)
• Ultrasonic testing (UT) for internal quality assessment
• Third-party inspection available (SGS, Bureau Veritas, TÜV, DNV, etc.)

Certification & Documentation

Each shipment includes comprehensive documentation:

✓ EN 10204 3.1 mill test certificate with full test results
✓ Classification society approval certificate (ABS, LR, BV, DNV, etc.)
✓ Heat number traceability for full material history
✓ Optional EN 10204 3.2 certificate available upon request

Why Choose CEHE Steel for Your Marine Steel Needs?

Discover how our expertise, resources, and commitment make us the preferred partner for marine steel solutions worldwide.

Powerful Resource Network and End-to-End Supply Assurance

Through alliances with 7 top-tier Chinese steel mills, we turn your custom steel requirements into reality—backed by classification society-certified inventory that stands ready to resolve rush orders and critical stockouts at a moment's notice.

Resource & Dimensions
Thickness: 6-150mm, Width: up to 5300mm, Length: up to 18000mm
Strategic Inventory
We have reserved a certain amount of CCS, ABS, BV, RINA in stock for you to quickly solve the urgent needs of ship body repair 
Global Logistics
Professional packaging with real-time tracking worldwide.
Supply Chain Control
We provide custom steel plate service with the fastest delivery cycle of up to 15 days.

Comprehensive Quality System and Transparent Traceability

We implement a quality control and traceability system that exceeds standard requirements, ensuring every steel plate we supply is reliable, compliant, and fully documented.

Full Certification
Meets ABS, DNV, GL, LR, BV, CCS, NK, RINA, KR standards.
Stringent Inspection
Third-party inspection support (SGS, BV) with rigorous internal QC.
Complete Traceability
Unique heat number tracking from mill to project.
Quality Standards
EN 10204 3.1/3.2 certificates with every shipment.

Technical Expertise and Comprehensive Project Support

We position ourselves not just as material suppliers but as technical partners, offering complete service from material selection through to final delivery and beyond.

Expert Consultation
Free technical guidance on material selection, welding, fabrication.
Project Follow-up
Immediate response, risk assessment, contract review, production tracking.
Value-Added Services
Export documentation, logistics arrangement, inspection coordination.
Continuous Support
From order confirmation to post-installation.

Proven Experience and Global Trust Since 2009

Since our founding in 2009, we have built deep expertise in marine steel applications and validated our capabilities through successful projects worldwide.

Industry Experience
Focused exclusively on marine steel since 2009
Global Performance
Successfully supplied major shipbuilding and offshore projects worldwide.
Trusted Partner
Long-term relationships with marine plate distributors and manufacturers.
Project Validation
Validated capabilities through successful global projects.

Frequently Asked Questions

AH40 is primarily used for high-strength hull structures, strength decks, hatch coamings, and other critical components of large vessels operating in temperate and warm waters. It is ideal for applications requiring superior load-bearing capacity with 390 MPa yield strength, enabling weight reduction and design optimization in modern shipbuilding.

The main difference is yield strength. Both AH40 and AH36 are impact tested at 0°C, but AH40 has a higher minimum yield strength of 390 MPa, compared to AH36's 355 MPa. AH40 offers even greater load-bearing capacity for the most demanding high-stress areas, allowing for further weight savings in vessel design.

AH40 is impact tested at 0°C (32°F) in accordance with classification society requirements for standard temperature marine service conditions, but with higher absorbed energy requirements (min. 41J longitudinal) compared to lower strength grades.

We provide EN 10204 3.1 mill test certificates along with classification society approval certificates for each shipment, including specific documentation for 0°C impact testing and 390 MPa yield strength verification.

Yes, we can supply AH40 plates with certifications from major classification societies including ABS, BV, DNV, LR, CCS, NK, KR, and RINA. We can work with your designated classification society to meet specific project requirements for high-strength applications.

Yes, we can arrange third-party inspections from organizations like SGS, Bureau Veritas, TUV, or Lloyd's Register upon customer request, including verification of 0°C impact test results and 390 MPa yield strength testing.

The price of AH40 steel plate fluctuates based on raw material costs, thickness, dimensions, purchase volume, and market conditions. For the most accurate and competitive real-time quotation, please contact our sales team with your specific requirements (grade, size, quantity, destination port, and any special certifications needed). We provide competitive pricing and respond within 24 hours.

Information You May Find Relevant

Pricing Range for AH40

Pricing is typically based on a benchmark price, with additional premiums applied for variations in thickness and supplementary processing requirements. AH40 typically commands a premium over AH36 due to its higher strength and alloying requirements.

Width range: 2000-2500mm for all specifications below

Thickness Thickness Premium Normalizing/TMCP Surcharge Total vs. Base
14-30mm (Base) — — Base price "b" (b > a for AH32)
12mm +60 — b + 60
10mm +180 — b + 180
8mm +400 — b + 400
32-40mm +60 — b + 60
42-50mm +120 +250 b + 370
50-52mm +180 +250 b + 430

* All price adjustments are in RMB. Actual pricing may vary based on market conditions, order volume, and specific requirements.

Request Technical & Commercial Support

Get Professional Support for Your AH40 Project

We supply classification-approved AH40 high-strength shipbuilding steel plate with 0°C impact toughness, 390 MPa yield strength, full traceability, flexible inspection options, and coordinated logistics support.

📋 Certification & Quality

• Adhere to classification society specifications and corresponding manufacturing standards

• Mill's EN 10204 3.1 certificate included in quality documentation

• Third-party onsite certification available upon request for customized plates

⚙️ Custom Solutions

• Custom thickness, width, length; widths ≤1600mm can be supplied via split delivery from double-width rolling

• 100% customizable: carbon equivalent, simulated post-weld, Z-direction properties, etc.

• Fastest delivery for hot-rolled custom plates: 10 days

Response Time: We typically respond to all inquiries within 24 hours

📩 Get AH40 Steel Plate Quotation

📝 Maximum 10 rows can be entered in this table. If you need more rows, please enter detailed requirements in the text box below, or send them to us via email.

Material Thickness (mm) Width (mm) Length (mm) Quantity Weight (ton) Action

You will receive a confirmation email after submission, and we will respond within 24 hours.