High strength steel for thick wall water pipe and manufacturing method thereof

Abstract

The invention provides a high strength steel for a thick wall water pipe. The steel comprises the following components: 0.040%-0.070% of C, 0.10%-0.40% of Si, 1.50%-1.65% of Mn, 0.050%-0.080% of Nb, 0.030%-0.050% of V, 0.20%-0.30% of Cr, 0.005%-0.025% of Ti, 0.015%-0.050% of Als, less than or equal to 0.020% of P, less than or equal to 0.008% of S, less than or equal to 0.008% of N, less than or equal to 0.002% of O, and the balance Fe and inevitable impurities. The manufacturing method of the steel includes: conducting continuous casting to make a continuous casting plate blank, subjecting the continuous casting plate blank directly to hot charging furnace heating at 500-850DEG C, heating the continuous casting plate blank by a reheating furnace to 1150-1230DEG C, discharging it, then carrying out two-stage controlled rolling by roughing rolling and finish rolling units, controlling the initial rolling temperature of rough rolling at 1180-1100DEG C and the final rolling temperature of rough rolling at 1010-960DEG C, keeping the initial rolling temperature of finish rolling at 980-920DEG C and the final rolling temperature of finish rolling at 780-850DEG C, and maintaining the compression ratio of finishing rolling greater than 60%; then subjecting a steel strip to rapid cooling by means of laminar cooling at a speed of 10-20DEG C / s; and performing reeling at 500-580DEG C.

Description

technical field [0001] The invention belongs to the technical field of high-strength low-alloy steel manufacturing, and in particular relates to a high-strength, thick-walled steel for water conveying spiral welded pipes and a manufacturing method thereof. Background technique [0002] With the gradual shortage of water resources in our country, the economic development and people's production and life of various cities are seriously affected. For this reason, governments at all levels have begun to build large-scale long-distance drinking water projects, of which pipelines account for a large part. The materials of large-diameter water pipelines usually include ductile steel pipes, cast iron pipes, prestressed steel cylinder concrete pipes, and glass fiber reinforced plastic sand pipes. In practical applications, steel pipes perform best. Although bursts and leaks do occur, they are much less than gray cast iron pipes and concrete pressure pipes. [0003] Compared with ot...

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Problems solved by technology

[0021] In order to overcome the shortcomings of the above-mentioned prior art, the purpose of the present invention is to solve the technical problems of adding more precious alloy elements (Mo, Ni, etc.) and high production costs in the prior art, and provide a low-cost production of high-strength thick-walled water delivery Steel for pipes and manufacturing method thereof, especially steel for high-strength thick-walled large-diameter water-transporting spiral welded pipes and manufacturing method thereof

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