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ASTM A131 AH40 Shipbuilding Steel Plate | Grade A Higher-Strength Hull Steel, 390 MPa Min Yield, Charpy Tested at 0 °C
ASTM A131 / A131M | Grade A — Charpy V-Notch Tested at 0 °C | Yield 390 MPa Min, Tensile 510–650 MPa, Elongation 22% Min | The Highest Strength Level of the Grade A Family | For Shipyard Crane & Heavy Lifting Projects
390 MPa Min Yield, 510–650 MPa TensileGrade 40 of the ASTM A131 higher-strength family — a minimum yield point of 390 MPa (40 kgf/mm²) with tensile strength held within 510–650 MPa.
Grade A — 0 °C ToughnessThe A designation requires the Charpy V-notch impact test at 0 °C: 27 J transverse and 41 J longitudinal on plate up to 50 mm thick.
Specified for Shipyard Crane WorkUsed for building crane projects under high-strength situations in shipyards — booms, pedestals and gantry girders where a 32 or 36 strength plate will not carry the section.
01Product Overview
ASTM A131 Grade AH40 is a grade A higher-strength hull structural steel plate with a minimum yield point of 390 MPa and a tensile strength within 510–650 MPa. The 40 in the grade name is the specified minimum yield point expressed in kgf/mm², and the A fixes the Charpy V-notch test temperature at 0 °C — the entry level of the four quality levels on the A131 ladder.
Under the steel specification ASTM A131 / A131M, marine steel plate and sheet of grade AH40 are mainly used for building cranes project under high strength situation in many shipyards. Because the A level only has to prove toughness at 0 °C, the alloying budget goes into strength: AH40 is the highest strength level of the grade A family, above AH36 (355 MPa) and AH32 (315 MPa). That is what makes it the natural call-up for crane and lifting structures where the section is limited by strength rather than by low-temperature service.
390 MPaYield Strength (Min)ASTM A131 AH40
510–650 MPaTensile StrengthASTM A131 AH40
0 °CImpact Test TemperatureGrade A designation
22 %Elongation (Min)A131 AH40
02Technical Specifications
ASTM A131 Grade AH40 plate supplied to your drawing, with cutting, shaping and full marine certification handled on the same order.
Produced to order — thickness, width and length confirmed against your drawing and the rolling schedule
Surface Condition
Smooth surface, uniform texture, no cracks, no rust spots
Delivery Condition
Confirmed per order and stated on the MTC As RolledNormalizedTMCPOther as agreed
Custom Production
Available — custom sizes, cutting and shaping to your drawings
MOQ
1 Ton / Negotiable
Delivery Time
Stock availability and rolling schedule confirmed on enquiry
Certification
MTC / EN 10204 3.1 / Classification society certificate (ABS, CCS, DNV, LR)
Payment Terms
T/T, L/C, Western Union, Trade Assurance
Note: ASTM A131 / A131M does not fix a single size range or delivery condition for AH40 — the applicable thickness, rolling schedule and heat treatment are agreed between buyer and mill for each order and stated on the MTC. Send us your required thickness, width, length, quantity and classification society and we will confirm stock status and the exact delivery condition against the item before you order.
03Grade Designation
Each segment of the grade name carries a defined meaning in ASTM A131 / A131M — and grade A is what separates AH40 from the DH, EH and FH grades.
Designation Segment
Meaning in ASTM A131 / A131M
A
Grade A — the quality / toughness level tested at 0 °C (the four levels are A = 0 °C, D = −20 °C, E = −40 °C, F = −60 °C)
Specified minimum yield point in kgf/mm² — 40 kgf/mm² ≈ 390 MPa, the highest strength number offered at the grade A level
Note: The A tells you the Charpy V-notch test temperature (0 °C) and the 40 is the yield point expressed in kgf/mm² (40 kgf/mm² ≈ 390 MPa), which is exactly the minimum yield value given in the mechanical table — a useful cross-check when you read a mill certificate. The designation breakdown above is standard background for this grade family.
04Equivalent & Classification Society Grades
For global shipbuilding and crane project bidding, ASTM A131 AH40 has matching grade-A equivalents under the major classification societies, so the same grade level can be procured across standards.
Standard System
Equivalent Grade
Note
ABS Standard
ABS AH40
American Bureau of Shipping approval for hull structures
CCS Standard
CCS AH40
China Classification Society approval
DNV Standard
DNV AH40
Det Norske Veritas approval
LR Standard
LR AH40
Lloyd’s Register approval
Other IACS societies
BVKRNKRINA
AH40 approvals of the remaining IACS members are available on request
Note: Equivalent grade-A grades differ slightly in chemical composition and production process. Verify welding parameters and inspection standards against your actual ship classification requirements before substituting one for another.
05Chemical Composition
Chemical composition for A131 AH40 ship steel — heat analysis, % max unless a range is given.
Grade
C
Si
Mn
P
S
Al (acid) min
Nb
V
Ti
Cu
Cr
Ni
Mo
N
A131 AH40
0.18
0.10–0.50
0.90–1.60
0.035
0.035
>0.015
0.02–0.05
0.05–0.10
0.02
0.35
0.20
0.40
0.08
—
Note: AH40 caps carbon at 0.18% and phosphorus and sulphur at 0.035% each, keeps silicon in the 0.10–0.50% range, carries nickel at 0.40% and specifies aluminium as a minimum of 0.015% as the grain refiner. Niobium (0.02–0.05%) and vanadium (0.05–0.10%) are the micro-alloying ranges that develop the 390 MPa yield without sacrificing weldability, while the capped P and S keep the weld heat-affected zone tough at 0 °C. The data sheet for this grade does not set a nitrogen limit, so the N cell is left blank here — where a project or a classification society sets a nitrogen cap, it is stated on the mill certificate. Contents of any other intentionally added element are determined and reported.
06Welding Performance Parameters
Two indices are used to evaluate welding crack sensitivity and carbon equivalent for production and welding process guidance.
Note: Lower Pcm and Ceq mean better weldability and lower preheat demand. Both are calculated from the actual heat analysis of each plate, so we quote the values together with the MTC rather than as fixed numbers. Because AH40 sits at the 40 strength level — the highest of the grade A family — its carbon equivalent normally runs above the grade 32 and grade 36 plates, so preheat and interpass control matter more on heavy crane sections. Confirm preheat and interpass requirements against your welding procedure specification before fabrication.
07Mechanical Properties
Mechanical property for A131 AH40 shipbuilding structural steel, given by plate thickness bracket together with the Charpy V-notch impact values.
Grade
Thickness
Yield Strength Min
Tensile Strength
Elongation Min
Impact Test Temperature
Energy 1 (Transverse)
Energy 2 (Longitudinal)
A131 AH40
t ≤ 50 mm
390 MPa
510–650 MPa
22 %
0 °C
27 J
41 J
A131 AH40
50 < t ≤ 70 mm
390 MPa
510–650 MPa
22 %
0 °C
—
—
A131 AH40
70 < t ≤ 100 mm
390 MPa
510–650 MPa
22 %
0 °C
—
—
Note:Energy 1 is the transverse impact test and Energy 2 is the longitudinal impact test. Strength and elongation are the same across all three thickness brackets — 390 MPa minimum yield, 510–650 MPa tensile and 22% minimum elongation. The data sheet gives the Charpy V-notch energies for the t ≤ 50 mm bracket (27 J transverse, 41 J longitudinal at 0 °C) and marks the 50–70 mm and 70–100 mm brackets as not applicable in that source table, so those two cells are left blank here rather than filled with a value that source does not support. Tell us the thickness and the classification society and we will confirm the applicable energy from the mill certificate for your specific plate.
08Applications & Typical Components
Under ASTM A131 / A131M, marine steel plate and sheet of grade AH40 are mainly used for building cranes project under high strength situation in many shipyards.
1
Shipyard Cranes
Crane projects built in shipyards under high-strength situations — boom and jib plate, pedestals, slewing columns and gantry girders.
2
Lifting & Handling Equipment
Deck crane bases, lifting beams and spreaders, winch and hoist foundations where the section is strength-limited.
3
High-Strength Hull Structures
Hull structures, decks and ship sections engineered at the 40 strength level instead of 32 or 36, to save plate weight.
Application Field
Typical Application & Components
Shipyard Crane Projects
Crane boom and jib plates, pedestals and slewing columns, gantry and portal crane girders
Lifting & Handling Equipment
Deck crane bases, lifting beams and spreaders, winch and hoist foundations
High-Strength Hull Structures
Hull structural plate, decks and sections at the 40 strength level, built to classification society rules
Note: The same 40 strength level runs across the A131 quality ladder — AH40 is tested at 0 °C, DH40 at −20 °C, EH40 at −40 °C and FH40 at −60 °C. Grade A only earns its strength margin above freezing: if the structure works below 0 °C, or sits in a low-temperature service class, the D, E or F level of the 40 family is the correct call-up. Send us the design temperature and the required strength and we will confirm which grade your project actually needs.
09Processing & Fabrication Services
Every order can be cut, formed, blast cleaned, coated and independently inspected, so material arrives at the yard ready to fit.
1
Cutting
Custom sizes and shapes cut to your drawings, plate and profile.
2
Bending & Forming
Plate bending and shaping for crane sections and structural components.
3
Shot Blasting & Painting
Coated, or shot blasting and painting applied before shipment.
4
Inspection & Certified Delivery
MTC and EN 10204 3.1 with every shipment; UT, Z-direction test and third-party inspection (SGS) arranged on request.
We supply high-quality ASTM A131 AH40 shipbuilding steel plates with strict marine standard inspection and full traceability. We provide one-stop customized processing services including cutting, bending and forming, plus coated or shot blasting and painting to your surface specification. All products are equipped with official MTC test reports and marine certification documents, and UT, Z-direction and third-party (SGS) testing can be arranged on request. BBN Group is one of the leading manufacturers, suppliers and exporters of ASTM A131 Grade AH40 plates — welcome to contact us for professional quotations and technical support!
10Frequently Asked Questions
Short answers to the questions we are asked most often about ASTM A131 AH40. For anything not covered here, send us your drawings and specification.
Q1What does AH40 mean in ASTM A131?
A is the quality / toughness level — grade A requires the Charpy V-notch impact test at 0 °C. H means higher-strength hull structural steel. 40 is the specified minimum yield point in kgf/mm² (40 kgf/mm² ≈ 390 MPa) and is the highest strength number offered at the grade A level. AH40 therefore combines a 390 MPa minimum yield with a 0 °C impact requirement.
Q2What is the difference between AH40, AH36 and AH32?
All three are grade A, so all three are Charpy tested at 0 °C — they differ only in strength: AH32 = 315 MPa, AH36 = 355 MPa and AH40 = 390 MPa minimum yield. Choose AH40 when the section is strength-limited and the structure never works below freezing; if the member sees sub-zero service you need the D, E or F level of the same 40 strength family instead of a higher number at grade A.
Q3What is ASTM A131 AH40 mainly used for?
Under ASTM A131 / A131M, marine plate and sheet of grade AH40 are mainly used for building cranes project under high strength situation in many shipyards — crane booms and jibs, pedestals, gantry and portal crane girders, plus deck crane bases, lifting beams and other lifting and handling equipment where the 390 MPa yield lets the section stay thinner.
Q4What impact toughness does A131 AH40 guarantee?
Grade A fixes the test temperature at 0 °C, tested as a Charpy V-notch specimen: 27 J transverse and 41 J longitudinal for plate up to 50 mm thick. Energy 1 is the transverse test and Energy 2 is the longitudinal test. For the 50–70 mm and 70–100 mm brackets the source data sheet marks the energy as not applicable, so we confirm the applicable requirement from the mill certificate for your specific plate rather than printing a number the source does not give.
Q5What sizes and delivery conditions can you supply?
Plate is produced to order — thickness, width and length are confirmed against your drawing and the rolling schedule, and ASTM A131 / A131M does not lock AH40 to one delivery condition, so as rolled, normalized, TMCP or another agreed condition is stated on the MTC per order. MOQ is 1 ton, payment is by T/T, L/C, Western Union or Trade Assurance, and every shipment carries an MTC / EN 10204 3.1 certificate.
Q6Can A131 AH40 be substituted by ABS AH40 / CCS AH40 / DNV AH40 / LR AH40?
These are the grade-A equivalents of the same strength and toughness level and are commonly accepted for cross-standard procurement and bidding. There are slight differences in chemical composition and production process, so verify welding parameters and inspection standards against your actual ship classification requirements before material replacement. Tell us which classification society your project is surveyed under and we will supply the plate with the matching certificate.
Get Your ASTM A131 AH40 Shipbuilding Steel Plate Quotation
Send us your plate dimensions (thickness / width / length), quantity, delivery condition and classification society requirement. We will reply with the latest stock status, competitive wholesale price and complete marine certification documents within 24 hours.
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