Application: Offshore mooring chains have 5 grades: R3, R3S, R4, R4S, R5, among which the Grade R3 and R3S mooring chains are mainly used for marine continental shelf development facilities, while the R4 class chains are mainly used for deep-sea development facilities. Offshore mooring chains have the features of high strength, good toughness, seawater corrosion resistance, fatigue resistance, wear resistance.