ASTM A131 Grade A/B Marine Steel plate

Marine steel plate refers to structural steel used in ship building. It is considered a marine grade and must be able to resist corrosive effects that are common in a water environment. To achieve this, special alloying elements are added to these grades in order to defend agaist corrosion.While most carbon steel is not suited for marine environments, there are several marine grade carbon steels that have been approved by the different societies for shipbuilding applications.

Structural steel for ship hulls is divided into strength classes according to its minimum yield strength: general strength structural steel and high strength structural steel.  Maine steel plate refers to hot rolled steel plate produced in accordance with the requirements of the classication society for the construction of ship hull structures. The general strength steel s of the China Classification Society are divided into four quality grades: A B D and E.

There are 9 main classification societies in worldwide
A.B.S    American Bureau of Shipping
B.V.     Bureau Veritas
C.C.S.   China Classification Society
D.N.V   Det Norske Veritas
G.L.    Germanischer Lloyd
K.R.    Korean Register of Shipping
L.R.    Lloyd’s Register of Shipping
N.K.    Nippon Kaiji Kyokai
R.I.N.A  Registro Italiano Navale

ASTM A131 is A structural grade of steel plate utilized almost exclusively in the shipbuilding industry. This grade is defined as ordinary strength with specified minimum yield of 34KSI(235Mpa). Applications include barges, marine equipment and ship construction. These grades are also certified by the American Bureau of Shipping(ABS)

This specification covers structural steel plates,shapes,bars and rivets intended primarily for use in ship construction.
Ordinary strength- Grade A B D CS and E with a specified minimum yield point of 34 ksi(235MPa)

Shipbuilding is central to America’s identity and American ingenuity shines in its submarines, yachts, cruise ships, and aircraft carriers. Great ships start with high-quality marine grade steel plate and Gnee is proud to supply the American shipbuilding industry with marine and offshore steel that’s corrosion-resistant and tough, demonstrating decreased brittleness, even in cold temperatures, and increased strength to resist force trauma and vibration. All of our marine grade plate meets the standards set by ABS (American Bureau of Shipbuilding), ASTM, and API (American Petroleum Institute). We’re a trusted supplier of marine & offshore steel plate across world and service shipbuilders

Chemical Requirement for Ordinary-Strength Structural Steel

Element	Grade A	Grade B	Grade D	Grade E	Grade CS
	Deoxidation and Thickness(t) in mm
	t>2.0 in(50mm)	t>2.0 in(50mm)	t>1.0 in(50mm)
C	0.21	0.21	0.21	0.18	0.16
Mn min	2.5XC	0.60	0.60	0.70	1.00
Si	0.50	0.35	0.10-0.35	0.10-0.35	0.10-0.35
P	0.035	0.035	0.035	0.035	0.035
S	0.035	0.035	0.035	0.035	0.035
Ni	-	-	-		-
Cr	-	-	-	-	-
Mo	-	-	-	-	-
Cu	-	-	-	-	-
C+Mn/6	0.40	0.40	0.40	0.40	0.40

Tensile Requirement for Ordinary-Strength and Higher-Strength Structural Steel

Grade	Tensile Strength ksi(Mpa)	Yield Strength min ksi(Mpa)	Elongation in 8 in (200mm) %	Elongation in 2 in (50mm) min %
Ordinary strength A B D CS E	58-75(400-520)	34(235)	21	24