Wide and thick steel plates for normalizing rolled fine grain pressure welded steel pipes

Abstract

The invention discloses a wide and thick steel plate for a normalized and rolled fine-grain pressure-welded steel tube and a preparation method thereof. The wide and thick steel plate comprises the following chemical components in percentage by weight: 0.08-0.16% of C, 0.20-0.60% of Si, 1.20-1.70% of Mn, less than or equal to 0.020% of S, less than or equal to 0.025% of P, less than or equal to 0.050% of Nb, less than or equal to 0.050% of V, less than or equal to 0.050% of Ti, more than or equal to 0.020% of Als, and the balance of Fe and trace impurities. The preparation method comprises the following steps: heating a plate blank to 1150-1250 DEG C, wherein the heating time is more than or equal to 200min and the soaking time is more than or equal to 50min; normalizing and rolling, wherein in a rough rolling stage, the initial rolling temperature is 1150-1200 DEG C, the final rolling temperature is 1100-1160 DEG C and reduction rates in the last three processes in the rough rolling stage are ensured to be more than or equal to 20%, and in a finish rolling stage, the initial rolling temperature is 850-920 DEG C, the thickness of an intermediate blank is 3-6 times of that of a finished product and the final rolling temperature is 800-850 DEG C; and after the final moulding rolling, weakly cooling the steel plate on line to 600-700 DEG C through a multi-functional batch-type accelerated cooling system, and then cooling the steel plate to room temperature in air.

Description

technical field [0001] The invention relates to the technical field of production of wide and thick plates, in particular, the invention relates to a wide and thick steel plate for normalizing rolled fine-grain pressure welded steel pipes and a preparation method thereof. Background technique [0002] Steel for fine-grain pressure welded steel pipes is widely used in petrochemical industry, oil and gas transportation, pressure pipeline, pressure vessel manufacturing and other fields. Due to the complex and harsh service environment and wide range of applications, there are high requirements for steel plate transverse and longitudinal strength uniformity, low temperature toughness, grain size, microstructure uniformity, mechanical property stability and welding formability, so the products generally adopt off-line normalizing Heat treatment is used to refine the grain, stabilize the structure and mechanical properties, and reduce the band structure level. However, the off-lin...

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Problems solved by technology

[0003] At present, domestic patents related to normalizing rolling technology include "A Method for Producing Medium and Heavy Plates of Pipeline Steel with Excellent Toughness by Normalizing Rolling" with the publication number CN101921955A, "A Micro-alloyed Bridge Steel Plate" with the publication number CN102766808A and its normalizing rolling process", etc., the above-mentioned patents use low-temperature heating, low-temperature high-pressure rolling and other technologies to produce pipeline steel, bridge steel, etc., but the microstructure uniformity, band Little attention has been paid to the control effect of important indicators such as microstructure, stability and uniformity of mechanical properties, and how to further improve and improve the microstructure and mechanical properties of normalized rolled steel plates.

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