The boats make a huge impact in our world, not just transport goods, also people can use it to pass the river, ocean and more. It makes our world have more and more possible. But what is steel for boats? Maybe many people do not know about it. There are two types of steel for boats. They are high-quality carbon steel and low alloy steel. About the high-quality carbon steel, you may be heard about 1045 steel, 1050 steel and more. But about the low alloy steel, it is bigger than carbon steel in the parts of steel. There are a lot of types for it. Such as the 4140 steel, 4130 steel and etc. The steel for the boat which is used to make the hull structure for sea and riverboats. High strength, toughness, welding and great low-temperature and corrosion resistance are the most important point for hull steel.
Steel Types for Boat
Commonly used hull structural steel includes general strength steel (A, B, D, E) steel plates specified in GB712, high strength steel (AH32, DH32, EH32, AH36, DH36, EH36) steel plates; high-quality carbon for ships specified in GB5312 Plain steel (CIO, C20) steel pipes; Class A and B steel ball flat steel for shipbuilding as specified in GB9945.
General strength hull structural steel is divided into 4 grades: A, B, D, E. The yield strength (bigger than 235N / mm ^ 2) and tensile strength (400 ~ 520N / mm ^ 2) of these 4 grades are the same. But the ballistic work is different at different temperatures.
According to the min yield strength to make the high-strength hull structural steel divided into different levels. And every level also has A, D, E, F four-level according to different impact toughness. A, D, E, and F respectively represent the impact toughness that can be achieved under the conditions of 0 °, -20 °, -40 °, and -60 °, respectively.
The yield strength of A32, D32, E32, F32 is bigger than 315N / mm ^ 2, and the tensile strength is 440 ～ 570N / mm ^ 2.
The yield strength of A36, D36, E36, F36 is not less than 355N / mm ^ 2, and the tensile strength is 490 ～ 620N / mm ^ 2.
The yield strength of A40, D40, E40, and F40 is higher than 390 N / mm ^ 2, and the tensile strength is 510 to 660 N / mm ^ 2.
Due to the badness working environment of the boat, the hull of the boat is subject to chemical corrosion, electrochemical corrosion of seawater, and corrosion of marine organisms and microorganisms. The hull must absorb large wind and wave impacts and alternating loads. And the shape of the boat makes its processing method complicated. Therefore, strict requirements are imposed on the steel used for the hull structure.
First, good toughness is the most critical requirement. In addition, higher strength, good corrosion resistance, welding performance, processability and surface quality are required. In order to maintain quality and ensure sufficient toughness, the Mn / C of the chemical composition is required to be above 2.5, and the carbon equivalent is also strictly required, and it is produced by a steel mill approved by the ship inspection department.
The structural grades of hull structural steel according to its minimum yield point are general strength structural steel and high strength structural steel. Structural steel for hulls is divided into general strength and high strength steel. General strength steel is divided into four grades A, B, D and E according to quality.
The general strength structural steels of CCS specifications are divided into: A, B, C, D four quality grades (ie CCSA, CCSB, CCSC, CCSD), and the high-strength structural steels of CCS specifications are three Intensity level, four quality levels.
In general, using steel as material to make the boat is a good move. But the disadvantage also with it. When you wanna buy one for you, you need to think about it more carefully.