Offshore and marine-quality steel plate contains chemical elements that resist corrosion

Offshore and marine-quality steel plate contains chemical elements that resist corrosion, decrease brittleness – especially in cold temperatures – and increase strength and toughness to resist vibration and force traumas.

 

Offshore and marine-quality steel plate contains chemical elements that resist corrosion, decrease brittleness – especially in cold temperatures – and increase strength and toughness to resist vibration and force traumas.

 

Shipbuilding steel plate is hot rolled steel plate which is produced as per Bureau of Shipping Standard and is used for manufacturing hull structure. According to minimum yield strength, it is classified as general strength and high strength hull structural steel. As per CCS standard, general strength structural steel has four grades: CCSA, CCSB, CCSD, CCSE; high strength structural steel has three strength grades, each strength grade has four quality grades.

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Bureau of shipping: CCS、ABS、GL、LR、 DNV 、BV、RINA、NK、KR

 

Thickness: 3.0-80mm

 

Width: 1500-4800mm

 

Length: 6-12 meters

 

Pack:bundled by steel strip

 

Low strength grade

 

A32	A36	A40
D32	D36	D40
E32	E36	E40
F32	F36	F40

 

High strength grade

 

AH32	AH36	AH40
DH32	DH36	DH40
EH32	EH36	EH40

 

Super high strength

 

NVA420	NVA460	NVA500
NVD420	NVD460	NVD500
NVE420	NVE460	NVE500

 

AH36, DH36, EH36 Steel Plate for Shipbuilding

 

Shipbuilding steel plate refers to the carbon and alloy steel plate used in offshore and marine constructions, common grades are A, B, D, E, AH32/36/40, DH32/36/40, and EH32/36/40 which ranged from different strength. The plates usually used to manufacture ship hulls, bulkheads, upper decks and hatch covers for tankers, bulk carriers, container ships and LNG carriers.

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AH36, DH36, EH36 Steel – Common Use High Strength Steel in Offshore & Marine.

 

For the high strength shipbuilding plates like AH36, DH36, EH36 steel plate, they have been widely used in high stress areas of ships, comparing with general strength steel, they are offering the same strength with the smaller thickness.

 

Shipbuilding steel material in carbon and alloy steel, compatible with high strength, low temperature and high heat input soldering.

 

Grades: A, B, D, E, AH32/36/40, DH32/36/40, EH32/36/40

 

According to its yield strength, shipbuilding plate of can be divided into below grades:Grade A steel is the impact force subjected to normal temperature (20 ° C).

 

Grade B steel impact force at 0 °C.

 

Grade D steel impact force at -20 °C.

 

Grade E steel impact force at -40 °C.

 

High-strength shipbuilding steel plate can be further divided into: AH32, DH32, EH32; AH36, DH36, EH36 and AH40, DH40, EH40.

 

The general grades A, B, D, and E are distinguished according to the impact temperature of the steel. The impact values of all grades of steel are the same.

 

High-intensity hull structure steel preheating requirements: For all AH, DH, EH plate thickness greater than 30mm angle, butt joints, shall be preheating to 120 ~ 150 °C before welding.

 

For thickness of the plate ≤ 30mm, the ambient temperature is below 5 ° C, preheated to 75 ° C; Ambient temperature below 0 ° C, preheated to 75 ~ 100 ° C.

 

Chemical and Mechanical Requirements

 

Elements	C	Mn	Al	Si	P	S
AH32	≤0.18	0.7~1.60	≥0.015	0.10~0.50	≤0.04	≤0.04
DH32	≤0.18	0.90~1.60	≥0.015	0.10~0.50	≤0.04	≤0.04
EH32	≤0.18	0.90~1.60	≥0.015	0.10~0.50	≤0.04	≤0.04
AH36	≤0.18	0.7~1.60	≥0.015	0.10~0.50	≤0.04	≤0.04
DH36	≤0.18	0.90~1.60	≥0.015	0.10~0.50	≤0.04	≤0.04
EH36	≤0.18	0.90~1.60	≥0.015	0.10~0.50	≤0.04	≤0.04

 

C (carbon) is an indispensable strengthening element in steel, but the increase in C content reduces the low-temperature impact toughness of steel and deteriorates the weld-ability of steel. Therefore, it is necessary to control the C content in the steel.

 

According to the experience of producing aluminium-containing steel, in order to ensure the aluminium content in the steel and the fluidity of the molten steel, the method of pre-deoxidation is strictly to control the carbon content of the end point and the alloying of the large-pack alloy to control the oxidation of the molten steel. The way of adding aluminium.

 

Processing for Different Grades

 

Grade A and B

 

The general strength of grade A and B shipbuilding steel plates can meet the requirements of process and mechanical properties through ordinary rolling, so the production process is relatively simple.

 

Grade D, E (DH32, DH36, EH 32, EH 36)

 

Grade D and E series (Including AH32/36, DH32, DH36, EH32, EH36) shipbuilding steel plates require good low temperature toughness and good welding performance. The production high-strength shipbuilding steel plate needs to be normalized by means of controlled rolling and controlled cooling or heat treatment processes with more complete equipment.

 

Alloy Elements Added to Improve Toughness

 

In order to ensure the performance of high-strength ship plates, micro-alloying technology is adopted. By adding Nb, V, Ti and other alloying elements to the steel, combined with the controlled rolling process, the grain is refined and the toughness is improved.

 

Mechanical Properties
Steel Grade	Thickness/mm	Yield point / MPa	Tensile strength / MPa	Elongation/ %	Temperature/℃	Average impact absorption workAkv/J​
						Vertical	Horizontal
A	≤50	≥235	400~490	≥22	–	–	–
B	≤50	≥235	400~490	≥22	0	≥27	≥20
D	≤50	≥235	400~490	≥22	-10	≥27	≥20
E	≤50	≥235	400~490	≥22	-40	≥27	≥20
AH32	≤50	≥315	440~590	≥22	0	≥31	≥22
DH32	≤50	≥315	440~590	≥22	-20	≥31	≥22
EH32	≤50	≥315	440~590	≥22	-40	≥31	≥22
AH36	≤50	≥355	490~620	≥22	0	≥34	≥24
DH36	≤50	≥355	490~620	≥22	-20	≥34	≥24
EH36	≤50	≥355	490~620	≥22	-40	≥34	≥24