Corrosion resistant steel with superfine bainite surface layers for ships and manufacturing method thereof

• Main Authors: SU HANG, WANG RUIZHEN, CHAI FENG, LI LI, WANG ZHUO, SHEN JUNCHANG, PAN TAO, LIANG FENGRUI, LUO XIAOBING, YANG CAIFU, XUE DONGMEI, CHEN XUEHUI, HOU YAQING
• Format: Patent
• Language: English
• Published: 25.03.2015
• Subjects: ALLOYS; CHEMISTRY; FERROUS OR NON-FERROUS ALLOYS; GENERAL DEVICES FOR HEAT TREATMENT OF FERROUS OR NON-FERROUSMETALS OR ALLOYS; MAKING METAL MALLEABLE BY DECARBURISATION, TEMPERING OR OTHERTREATMENTS; METALLURGY; METALLURGY OF IRON; MODIFYING THE PHYSICAL STRUCTURE OF FERROUS METALS; PROCESSING OF PIG-IRON, e.g. REFINING, MANUFACTURE OFWROUGHT-IRON OR STEEL; TREATMENT IN MOLTEN STATE OF FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS

The invention provides corrosion resistant steel with superfine bainite surface layers for ships and a manufacturing method thereof, and belongs to the technical field of corrosion resistant steel for ships. The steel for cargo oil tanks contains 0.01-0.3% of C, 0.02-2% of Si, 0.1-2.0% of Mn, not larger than 0.01% of S, not larger than 0.02% of P, 0.05-2.0% of Ni, 0.05-2.0% of Cu, 0.0005-0.02% of Sr and 0.0005-0.02% of Ba, as well as 0.0005-0.02% of Ti, 0.003-0.3% of Nb and the balance of Fe and inevitable impurities. The manufacturing method of the corrosion resistant steel comprises the following steps: by adopting low-S-P raw materials, carrying out deoxygenation and desulfuration by adopting a barium alloy containing 10-50% of Si, 5-20% of Al, 5-20% of Ba, 1-10% of Ca, 1-10% of Sr and the balance of Fe, wherein the rolling start temperature of rough rolling of the corrosion resistant steel is 1000-1150 DEG C, the steel plate is quickly cooled to 600-500 DEG C at a speed larger than 10 DEG C/s after being rolled, when the temperature on the surface of the steel plate returns to 700-770 DEG C, second-stage non-recrystallization zone rolling is carried out, and the accumulated deformation is 50-60%. The corrosion resistant steel has the advantages that the corrosion resistance of the steel in a dry-wet alternate oil and gas environment and a strongly acidic chloridion environment can be significantly improved.