Explanation

The structural steel used to manufacture the hull structure of ocean going, coastal and inland navigation ships is mainly plate, and also includes some section steel and tube. hull steel requires high strength, high toughness, good weld performance and high seawater corrosion resistance. Since the whole hull is a large weld structure during ship manufacturing, in order to reduce the weld workload, shorten the construction period and improve the overall stiffness of the hull structure, steel for large ships mostly uses wide and thick plates and requires high heat input welding welding capability (weld heat input is greater than 50kJcm, up to 500kJcm). Its carbon equivalent should not be greater than 0.45. The structural steel for ships (GB712-2011) is mainly made of high-quality low-carbon structural steel, and its grades are internationally accepted. First, English letters are used to indicate the quality grade. At present, a large number of F grade steel with impact toughness of 60 ° C has been produced and used; The number after the letter indicates the yield strength grade (but the unit of value is kgfmm2, and lkgfmm2 is about 9.8MRi). Currently, 315~390MPa grade is mainly used in production; hull steel of higher strength level is represented by quality grade letter plus yield strength value (MPa). The steel used for ships is mostly alloy structural steel (with performance steel designation or code). The yield strength grade can reach above lOOOMPa.

Classification