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Analysis of ship steel plate characteristics

Ship steel plate is mainly used to manufacture the hull and deck of ocean-going, coastal and inland shipping ships and offshore engineering platforms. The working environment of ship steel plate is harsh, which not only requires to withstand chemical corrosion of seawater, electrochemical corrosion and corrosion of Marine organisms and microorganisms, but also requires to withstand larger wind and waves impact and alternating load, and more convenient welding processing. The technical requirements of the classification society of different countries for ship steel plate are different, but there is little difference, mainly concentrated in the following points:

(1) High strength, can reduce the thickness and mass of the ship body wall, adapt to the requirements of large hull, lightweight, high parameter;
(2) high toughness, including low temperature toughness, crack stop toughness, strength toughness, etc., can have a low ductile brittle transition temperature under low temperature conditions, can meet the cold, hot bending and water and fire bending plate forming operation, can prevent brittle fracture;
(3) Good welding performance, good crack resistance, no preheating or low temperature preheating, can be large line energy welding, can meet the requirements of low-cost automatic welding;
(4) Excellent fatigue resistance, higher ship steel plate purity, in the process of low C increasing Mn microalloying, to maintain the content of sulfur, phosphorus and other harmful elements is lower, element segregation is smaller, less non-metallic inclusions;
(5) Excellent corrosion resistance;
(6) Precise size, uniform thickness, larger length and width, can reduce the length of hull weld, increase hull safety.
(7) Good surface quality, no damage, no crack;

Ship steel plate is divided into three categories according to the strength level: general strength, high strength and ultra-high strength steel for ships and marine engineering structures. The requirements for upper yield strength are >235MPa, >315MPa, >420MPa. The general strength structural steel of CCS code standard is divided into four quality grades A, B, D and E (i.e. CCSA, CCSB, CCSD, CCSE), respectively requiring +20℃, -0℃, -20℃, - The impact test performance at 40℃ is not less than the corresponding specified value, the yield strength is required to be > 235 MPa, and the tensile strength is required to be 400-520 MPa.