A production method of thin steel plate for bridge structure with low yield ratio

Abstract

The invention discloses a production method of a thin steel plate for a bridge structure with low yield-tensile ratio. The thickness of the steel plate is 8mm to 16mm; chemical components of steel areprepared from the following ingredients in percentage by weight: 0.10 percent to 0.15 percent of C, less than or equal to 0.50 percent of Si, 1.20 percent to 1.50 percent of Mn, less than or equal to0.015 percent of P, less than or equal to 0.005 percent of S, 0.02 percent to 0.05 percent of Alt, 0.008 percent to 0.025 percent of Ti, less than or equal to 0.020 percent of Nb, 0.25 percent to 0.50 percent of Cr and the balance of Fe and inevitable impurity elements. The production method is characterized in that the steel plate with the thickness of 8mm to 16mm is produced through hot rollingand low-temperature tempering processes, gold phase tissues of the steel plate are prepared from ferrite, pearlite and bainite, and the grain size can reach 8 grade to 9 grade. A bridge plate produced by adopting the method has the advantages of good strength and toughness, the strength grade is Q420q, minus 40 DEG C impact power is more than or equal to 120J, the yield-tensile ratio is less thanor equal to 0.85, and the unevenness of the steel plate can be controlled to ensure that the unevenness is in the range of 3mm / m. The production method of the thin steel plate for the bridge structure with the low yield-tensile ratio disclosed by the invention has the advantages of simple process, low cost, easiness for batch production and stable quality of products, and moreover, use requirements on steel used in high-grade roads and railway bridge structures can be met preferably.

Description

Technical field[0001]The invention belongs to the technical field of low-alloy structural steel production, and particularly relates to a method for producing thin steel plates for bridge structures with a low yield ratio.Background technique[0002]Steel plates for bridge structures are mainly used to manufacture steel box girder, steel truss girder, steel pipe piles, bridge decks, side plates, guard plates and other bridge components. In order to meet the current development of bridge construction in the direction of large-span, high-speed, heavy-duty, and high safety, the performance requirements for the strength and toughness and yield ratio of bridge structural steel are increasingly strict. However, the existing methods for manufacturing steel plates for bridge structures, especially thin plates, are still insufficient in terms of strength and toughness, yield ratio, plate shape, and cost. For example, Chinese patent CN103233169B adopts controlled rolling and controlled cooling ...

AI Technical Summary

Problems solved by technology

However, the existing manufacturing methods of steel plates, especially thin plates, for bridge structures are still insufficient in terms of strength, toughness, yield ratio, plate shape, and cost.

For example, the Chinese patent CN103233169B adopts the controlled rolling and controlled cooling process, the final rolling temperature is low, and the grain size is controlled above 9.5 grades. Although the steel plate has good strength and toughness, the yield strength is relatively high, which can reach 0.90, and the unevenness of the steel plate The strength is only controlled at the level of 3~7mm / m; Chinese patent CN103352167B adopts TMCP+ high temperature tempering process, while ensuring the high strength and toughness of the steel plate, the yield ratio can be controlled below 0.80, but it adds more Ni, Mo, Alloys such as Cu have a relatively high alloy cost, and the thickness of the bridge plate involved in this invention is more than 20mm; Chinese patent CN102766806B adopts a normalizing process, which can obtain an ultra-wide and thin structural steel plate for bridges with good plate shape and performance meeting the standard requirements, but Its strength is only Q345 level

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