Low-yield-ratio longitudinal variable-thickness bridge steel and manufacturing method thereof

• Main Authors: LI XINLING, ZHANG TAO, LI JINGNIAN, ZHANG ZHE, YANG YING, JI WENBO, WANG YUBO, HAYASHIDA KO, CONG JINGONG
• Format: Patent
• Language: Chinese; English
• Published: 19.09.2023
• 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; MECHANICAL METAL-WORKING WITHOUT ESSENTIALLY REMOVINGMATERIAL; METALLURGY; METALLURGY OF IRON; MODIFYING THE PHYSICAL STRUCTURE OF FERROUS METALS; PERFORMING OPERATIONS; PUNCHING METAL; ROLLING OF METAL; TRANSPORTING; TREATMENT OF ALLOYS OR NON-FERROUS METALS

The invention provides low-yield-ratio longitudinal variable-thickness steel for a bridge and a manufacturing method of the low-yield-ratio longitudinal variable-thickness steel, the variable thickness of a steel plate is smaller than or equal to 50 mm, and the steel is prepared from, by weight, 0.10%-0.138% of C, 0.20%-0.39% of Si, 1.10%-1.40% of Mn, smaller than or equal to 0.010% of P, smaller than or equal to 0.003% of S, 0.04%-0.07% of Nb, 0.005%-0.015% of Ti, 0.01%-0.04% of Al, 0.28%-0.38% of CEV and the balance iron and inevitable impurities. The manufacturing method comprises the steps of smelting, continuous casting, rolling, heating, rolling and straightening. The yield ratio of the steel plate produced by the method is less than or equal to 0.75, and the performance of the same plate is uniform: the same plate is thin, the thickness end strength difference is less than or equal to 10MPa, the percentage elongation after fracture is less than or equal to 3%, the yield ratio difference is less than or