High-ductility steel for hot-bending bends and production method for hot rolled plates thereof

Abstract

The invention provides a high toughness steel for hot bending bent steel and a production method of hot rolling flat plate thereof. The chemical compositions of the steel (weight percentage) comprise: C of 0.04 percent to 0.12 percent, Si of 10 percent to 0.30 percent, Mn of 1.50 percent to 1.65 percent, Nb of 0.04 percent to 0.08 percent, Ti of 0.008 percent to 0.025 percent, Ni of 0.15 percent to 0.36 percent, Mo of 0.15 percent to 0.30 percent, remaining iron and unavoidable impurities. The production method of the hot rolling flat plate comprises smelting, refining outside the hearth and continuous casting. Steel rolling is adopted a controlled rolling controlled cooling technics. The heating temperature of plate blank is ranged from 1160 DEG C to 1220 DEG C. Rough rolling temperature is ranged from 1010 DEG C to 1150 DEG C. Precision rolling temperature is ranged from 800 DEG C to 950 DEG C. Controlled cooling speed after rolled is ranged from 15 DEG C /s to 30 DEG C /s. Terminal cooling temperature is ranged from 450 DEG C to 600 DEG C. The invention has reasonable ingredient design. The production cost of the invention can be reduced about 15 percent compared to the prior art. The hot rolling steel plate of the invention can get composite organization with bainite as main part and has good low temperature toughness. The ballistic power is larger than 220 J in 20 DEG C below zero and the shearing area of DWTT at 15 DEG C below zero reaches up to 90 percent. The yield strength of the product reaches up to 520MPa and the tension resistance reaches up to 570MPa. The hot rolling steel toughness of the invention is not reduced after treatment and has better obdurability.

Description

technical field [0001] The invention belongs to the field of low-carbon micro-alloy steel, and in particular relates to a production method for manufacturing high-pressure, large-diameter oil and gas pipeline hot-simmered bent pipe steel and its hot-rolled flat plate. Background technique [0002] Elbow is one of the important pipe fitting products on the pipeline. It mainly plays two roles on the pipeline. One is to change the direction of the pipeline according to the needs; The tensile and compressive stress and torque attached to the straight pipe due to the change of external environment temperature. The bent pipe is one of the most demanding structural parts in the pipeline. In the pipelines that have been built and operated, the pipeline accidents related to the bent pipe account for a relatively high proportion of the entire pipeline accidents. It can be seen that the comprehensive quality of the bent pipe is high or low. It is one of the bottlenecks restricting the...

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Problems solved by technology

Due to the lower carbon content and more other alloy elements, the patented

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