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Ship structures are determined by the ship's mission and intended service. These determine a ship's size, complexity and the function of the structural components.There are now five different qualities of steel employed in merchant ship construction. These are graded A, B, C, D and E.
GRADE A STEEL
This mild steel is used for ship structures measuring less than 20 mm, such as bulkheads.
GRADE B STEEL
This slightly stronger steel is used for structures measuring 20 to 25 mm.
GRADE D STEEL
Grade D steel is strong enough to resist cracks and is used for structures that measure more than 25 mm thick.
GRADE E STEEL
This type of steel is heat treated for the ultimate strength and is used for structures measuring 50 mm or more, making it the ideal material for high-stress parts of the ship, such as the keel.
Grade and Chemical Composition (%)of different Grade of Shipbuilding Steel
| Property | Grade A | Grade B | Grade D | Grade E |
| % of Carbon | 0.21 max | 0.21 max | 0.21 max | 0.18 max |
| % of Manganese | 2.5 times %C min | 0.8 times %C min | 0.6 times %C min | 0.7 times %C min |
| % of Silicon | 0.5 max | 0.35 max | 0.1– 0.35 | 0.1– 0.35 |
| % of Phosphorous | 0.035 max | 0.035 max | 0.035 max | 0.035 max |
| % of Sulphur | 0.035 max | 0.035 max | 0.035 max | 0.035 max |
| % of Aluminum | – | – | 0.015 min | – |
| Ultimate Tensile Strength (N/mm2) | 400-520 | |||
| Yield Strength (N/mm2) | 235 | |||
| % Elongation | 22 | |||
| Temperature at which Impact test is done (deg Cel) | NA | 0 | -20 | -40 |
Shipbuilding Steel Plate Mechanical Properties:
| Grade | Thickness (mm) | Yieldpoint(Mpa)≥ | Tensile Strength (Mpa) | Elongation（%）≥ | V-impact test | cold bend test | |||
| Temperature（℃） | Average AKV A kv /J | b=2a 180° | b=5a 120° | ||||||
| lengthways | crosswise | ||||||||
| ≥ | |||||||||
| A | ≤50 | 235 | 400~490 | 22 | — | — | — | d=2a | — |
| B | 0 | 27 | 20 | — | d=3a | ||||
| D | -10 | ||||||||
| E | -40 | ||||||||
For shipbuilding specifically, there is another type of steel called Arctic D. This special grade is formulated to hold strong even in extremely low temperatures and is often used for icebreakers.
GB T 5312 Carbon and carbon-manganese steel seamless steel tubes and pipes are mainly for ship use, also known as shipbuilding steel pipes. Under GB T 5312, there are mainly 5 steel grades: grade 320, 360, 410, 460 and 490. Each grade covers three levels: I, II, III.
Angle steel, commonly known as angle iron, is a long strip of steel whose sides are perpendicular to each other. There are equal angle steels and unequal angle steels. The two sides of equal angle steel are equal in width. The unequal angle steel is also known as L shape profile steel.
Flat bar steel can be produced according to the user's needs, with fixed thickness, width and length. It can reduce the cutting process for users, reduce the consumption of labor and materials, and also reduce the processing loss of raw materials.
Bulb flat steel for shipbuilding
The bulb flat steel is a kind of medium section material which is mainly used in the field of shipbuilding and bridge building, and the shipbuilding bulb flat steel is an auxiliary medium section material for shipbuilding.
The steel for shipbuilding and oil platform---FH40, is the high tensile strength steel.The shipbuilding steel FH40 is the Hull structural steel.We can provide FH40 shipbuilding steel plate price.
The steel for shipbuilding and oil platform---EH40, is the high tensile strength steel.The shipbuilding steel EH40 is the Hull structural steel.We can provide EH40 shipbuilding steel plate price.
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BBN SHIP STEEL FACTORY
