Steel plate for wind power tower in low temperature and manufacturing method thereof

Abstract

The invention discloses a steel plate for a wind power tower in a low temperature and a manufacturing method thereof. The chemical constituent of the steel plate comprises, by weight, 0.14%-0.17% of C, 0.25%-0.40% of Si, 1.35%-1.50% of Mn, not more than 0.020% of P, not more than 0.005% of S, 0.020%-0.045% of Al, 0.02%-0.04% of Nb, 0.005%-0.015% of Ti, and the balance being iron and ineluctable impurities. The heating temperature of the slab is 1150-1250 DEG C. Time is 0.5-1.1 min / mm. The rough rolling temperature is 970-1060 DEG C. The screwdown ratio of a single pass in each pass is not less than 8%. The screwdown ratio of the single pass in back 4-5 passes is not less than 10%. During finish rolling, the initial rolling temperature is between 870 DEG C and 930 DEG C and the final rolling temperature is between 830 DEG C and 860 DEG C. The screwdown ratio of the single pass in frontal 3 passes is not less than 12%. The cumulative screwdown ratio is not less than 60%. Hot straightening is carried out after finish rolling, stowing and slow cooling is carried out after hot straightening. The temperature is between 300 and 400 DEG. Time is between 16 and 24 h. The yield strength of the steel plate in the invention is not less than] 390 MPa. The tensile strength of the steel plate is not less than 520 MPa. The elongation rate is not less than 25%. The yield ratio is lower than 0.78. The Charpy impact energy at the vertical -40 DEG C V-shaped gap is not less than 120 J. The Charpy impact energy at the vertical -50 DEG C V-shaped gap is not less than 60 J.

Description

technical field [0001] The invention belongs to the field of low-carbon micro-alloy steel, and in particular relates to a hot-rolled steel plate for wind power towers with excellent low-temperature toughness and a production method thereof. Background technique [0002] Wind energy is an inexhaustible, clean and non-polluting renewable energy source. The development of wind power generation is of great significance to adjusting energy structure, reducing environmental pollution, and solving energy crisis. China is rich in wind energy resources. The national wind energy reserves that can be developed and utilized at a height of 10m exceed 1 billion kW, ranking third in the world after the United States and Russia. In my country, wind energy resource-rich areas are mainly distributed in Inner Mongolia, northeast, northwest, north China and southeast coastal areas. Among them, Inner Mongolia, Northeast China and Northwest China belong to the alpine regions, with an altitude of...

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Problems solved by technology

[0005] The steel plates for building wind power towers disclosed in the above patent documents do not mention the impact performance when the temperature is lower than -40°C, and some require controlled cooling, and some do not need controlled cooling, but the addition of V elements will lead to higher production costs.

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