10-80-mm high-strength low-crack sensitive steel SX780CF for large-scale hydroelectric project and preparation method thereof

Abstract

The invention discloses 10-80-mm high-strength low-crack sensitive steel SX780CF for the large-scale hydroelectric project and a preparation method thereof. The high-strength low-crack sensitive steel SX780CF comprises the following chemical components in percentage by mass (unit, wt%): 0.05-0.09% of C, 0.1-0.2% of Si, 1.0-1.3% of Mn, less than or equal to 0.010% of P, less than or equal to 0.005% of S, 0.6-0.9% of Ni, 0.15-0.25% of Cu, 0.2-0.4% of Cr, 0.4-0.6% of Mo, less than or equal to 0.1% of V+Nb+Ti, 0.015-0.045% of Als and the balance Fe and residual elements, wherein Ceq of the high-strength low-crack sensitive steel SX780CF is less than or equal to 0.52, and Pcm of the high-strength low-crack sensitive steel SX780CF is less than or equal to 0.25. By virtue of reasonable component design and a series of processing measures, a 10-80-mm-thick high-strength low-crack sensitive SX780CF steel plate, which is low in cost, is high in production efficiency, is high in yield and is good in surface quality, for the large-scale hydroelectric project is successfully developed; and according to an oblique Y type groove cold crack resistant test, the 10-80-mm high-strength low-crack sensitive SX780CF steel plate has good weldability.

Description

technical field [0001] The invention belongs to the field of plate production, and in particular relates to a high-strength and low-crack-sensitivity steel SX780CF for 10-80mm large-scale hydropower projects and a preparation method thereof. Background technique [0002] The steel used in hydropower is used in a special environment, and the requirements for the strength, toughness, welding performance, and corrosion resistance of the steel plate are very strict. SX780CF is a high-strength and low-crack-sensitive steel used in large-scale hydropower projects. It is mainly used for penstocks and volutes in hydropower stations. The pressure pipes and volutes are used to transport water from reservoirs, pressure forebays or surge chambers to turbines. Water pipes are generally in a pressurized state, which is characterized by the concentration of most or all of the water head of the hydropower station. Therefore, the steel for penstocks and volute casings needs to have high stre...

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Problems solved by technology

[0005] (1) The yield strength of the steel plate is only 550-600MPa and 660-700MPa respectively, and the mechanical properties of the steel plate can no longer meet the current high-strength requirements of steel for hydropower;

[0006] (2) During the preparation of the above-mentioned steel plates, the steel billet ignored the oxidation loss caused by the oxidation reaction of iron at high temperature during the heating process, resulting in surface decarburization, reduced mechanical properties and formed surface defects after rolling, which not only reduced the yield of steel products, Affect the surface quality of steel and affect the operation rate

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