Description

A131 Shipbuilding Steel Plate (specifically referring to the most commonly used A131 GrA) is a general-strength structural shipbuilding steel plate under the ASTM A131/A131M standard. Its core characteristics are: yield strength ≥245 MPa, tensile strength 440–570 MPa, no low-temperature impact strength requirements, and good weldability and formability. It is considered an “entry-level” Marine Steel Plate and is widely used in non-low-temperature/non-high-load hull sections.

Features of A131 Shipbuilding Steel Plate:

1. Standard: ASTM A131/A131M (American Society for Testing and Materials), corresponding to “Class A” ship plates from classification societies (such as ABS, LR, BV, CCS, etc.).

2. Strength Grade: General Strength, GrA yield strength ≥245 MPa, tensile strength 440–570 MPa; no low-temperature toughness requirements (distinct from GrB/GrD/GrE’s 0℃, -20℃, and -40℃ impact requirements).

3. Chemical Composition: Low carbon (C≤0.20%), controlled P≤0.040%, S≤0.040%, containing Mn (0.60–1.20%) and Si (0.15–0.50%), no mandatory microalloying (e.g., Nb/V/Ti).

4. Delivery Condition: Hot-rolled (AR) or normalized (N), typical thickness 6–150 mm (some up to 200 mm), width 1500–4000 mm.

5. Processing Performance: Passes 180° bending (bending mandrel d=3a), good weldability, suitable for non-critical cryogenic areas (approximately 70% of structural area) in tankers, bulk carriers, and other vessels.

Note: The A131 Shipbuilding Steel Plate series also includes high-strength grades (such as AH36, DH36, etc., where “H” = high strength, and “36” = yield strength ≈ 355 MPa), but unless otherwise specified, “A131 Shipbuilding Steel Plate” usually refers to GrA.

Applications of A131 Shipbuilding Steel Plate:

ASTM A131 Shipbuilding Steel Plate is mainly used in the manufacture of hull structures (such as hulls, decks, bulkheads, ribs, etc.) for ocean-going, coastal, and inland waterway vessels. It is also used in load-bearing welded structures such as offshore engineering platforms, offshore wind power foundations, and port machinery. According to strength, it is divided into ordinary grades (A/B/D/E) and high-strength grades (AH/DH/EH/FH32~40). Grade A (such as A131GrA) is used for general non-critical parts, while high-strength grades are used for main load-bearing structures.

1. Standard Strength Grades (A, B, D, E): A131 Shipbuilding Steel Plate is used in non-critical or low-stress areas of ships (such as superstructures and compartment bulkheads). Grade A has no low-temperature impact requirements, while Grades B, D, and E respectively possess toughness from 0°C to –40°C.

2. High Strength Grades (AH32/DH32/EH32…AH40/FH40): A131 Shipbuilding Steel Plate is used in high-load and low-temperature environments such as the main hull, decks, and cargo hatches. It is suitable for tankers, container ships, bulk carriers, LNG carriers, and vessels operating in polar regions.

3. Extended Applications: A131 Shipbuilding Steel Plate is used in marine engineering structures requiring good weldability, corrosion resistance, and toughness, including offshore drilling platforms, floating storage and off-road vehicles (FPSOs), cross-sea bridge components, and dock facilities.

Standards of Shipbuilding Steel Plate:

ASTM A131 Steel Plate Chemical Composition (max.)
Grade	C	Mn	Si	P	S	Others
Grade A	0.21	2.5xC	0.5	0.035	0.035
Grade B	0.21	0.6	0.35	0.035	0.035
Grade D	0.21	0.6	0.01-0.35	0.035	0.035
Grade E	0.18	0.7	0.01-0.35	0.035	0.035
AH32/DH32/EH32	0.18	0.90-1.60	0.10-0.50	0.035	0.035	Cb 0.02-0.05, V 0.05-0.10, Ti 0.02, Cu 0.35, Cr 0.20, Ni 0.40, Mo 0.08, Als min. 0.015
AH36/DH36/EH36
AH40/DH40/EH40
FH32/FH36/FH40	0.16	0.90-1.60	0.10-0.50	0.025	0.025

ASTM A131 Steel Plate Mechanical Properties
Grade	Yield Strength	Tensile Strength	Elongation in 8 in.	Elongation in 2 in.
Grade	min. MPa)	MPa	min. %	min. %
Grade A, B, D, and E	235	400-520	21	24
AH32 DH32 EH32 FH32	315	440-590	19	22
AH36 DH36 EH36 FH36	355	490-620	19	22
AH40 DH40 EH40 FH40	390	510-650	19	22

ASTM A131 Steel Plate Charpy V-Notch Impact Test Temperature
Grade	Temperature ⁰F [⁰C]
Grade A	68 [20]
Grade B AH32 AH36 AH40	32 [0]
Grade D DH32 DH36 DH40	-4 [-20]
Grade E EH32 EH36 EH40	-40 [-40]
FH32 FH36 FH40	-76 [-60]

Standard	Shipbuilding and Offshore Structure Steel Grades
ASTM A131	Grade A	Grade B	Grade D	Grade E
	AH32	DH32	EH32	FH32
	AH36	DH36	EH36	FH36
	AH40	DH40	EH40	FH40
EN 10225	S355G2+N	S355G3+N	S355G5+M	S355G6+M
	S355G7+M	S355G7+N	S355G8+M	S355G8+N
	S355G9+N	S355G9+M	S355G10+N	S355G10+M
	S420G1+Q	S420G1+M	S420G2+Q	S420G2+M
	S460G1+Q	S460G1+M	S460G2+Q	S460G2+M
API SPEC 2H	API 2H-42	API 2H-50

Steel Grade	C	Si	Mn	P	S	Als
A	≤0.21	≤0.50	≥2.5c	≤0.035	≤0.035
B	≤0.21	≤0.35	0.8~1.2	≤0.035	≤0.035
D	≤0.21	≤0.35	0.6~1.2	≤0.035	≤0.035	≥0.015
E	≤0.18	≤0.35	0.7~1.2	≤0.035	≤0.035	≥0.015
AH32	≤0.18	≤0.50	0.9~1.6	≤0.035	≤0.035	≥0.015
DH32	≤0.18	≤0.50	0.9~1.6	≤0.035	≤0.035	≥0.015
EH32	≤0.18	≤0.50	0.9~1.6	≤0.035	≤0.035	≥0.015
FH32	≤0.18	≤0.50	0.9~1.6	≤0.035	≤0.035	≥0.015
AH36	≤0.18	≤0.50	0.9~1.6	≤0.035	≤0.035	≥0.015
DH36	≤0.18	≤0.50	0.9~1.6	≤0.035	≤0.035	≥0.015
EH36	≤0.18	≤0.50	0.9~1.6	≤0.035	≤0.035	≥0.015
FH36	≤0.18	≤0.50	0.9~1.6	≤0.035	≤0.035	≥0.015
AH40	≤0.18	≤0.50	0.9~1.6	≤0.035	≤0.035	≥0.015
DH40	≤0.18	≤0.50	0.9~1.6	≤0.035	≤0.035	≥0.015
EH40	≤0.18	≤0.50	0.9~1.6	≤0.035	≤0.035	≥0.015
FH40	≤0.18	≤0.50	0.9~1.6	≤0.035	≤0.035	≥0.015

Standards and Classifications

Standard	Shipbuilding and Offshore Structure Steel Plate Grades
ASTM A131	Grade A	Grade B	Grade D	Grade E
	AH32	DH32	EH32	FH32
	AH36	DH36	EH36	FH36
	AH40	DH40	EH40	FH40
EN 10225	S355G2+N	S355G3+N	S355G5+M	S355G6+M
	S355G7+M	S355G7+N	S355G8+M	S355G8+N
	S355G9+N	S355G9+M	S355G10+N	S355G10+M
	S420G1+Q	S420G1+M	S420G2+Q	S420G2+M
	S460G1+Q	S460G1+M	S460G2+Q	S460G2+M
API SPEC 2H	API 2H-42	API 2H-50