High-strength high-flexibility low-yield-ratio fire resistant steel and production method thereof

Abstract

The invention provides high-strength fire resistant steel with the room-temperature yield strength being more than 460 MPa, the yield ratio being smaller than 0.80, the high-temperature yield strength at 600 DEG C being more than two thirds of the room-temperature yield strength (i.e. more than 307 MPa) and favorable impact flexibility, which comprises the following components by weight percent: 0.05 to 0.14 percent of C, 0.15 to 0.50 percent of Si, 0.5 to 1.2 percent of Mn, equal to or less than 0.025 percent of P, equal to or less than 0.015 percent of S, 0.10 to 0.40 percent of Cu, 0.10 to0.50 percent of Ni, 0.015 to 0.050 percent of Nb, 0.005 to 0.040 percent of Ti, 0.010 to 0.050 percent of V, 0.10 to 0.50 percent of Cr, 0.20 to 0.50 percent of Mo, 0.015 to 0.05 percent of Al, Fe and foreign matters. The invention also provides a production method of the fire resistant steel, which comprises the following steps: liquid steel is obtained through vacuum melting, and the liquid steel is cast to form a billet; after the billet is heated to 1150 to 1250 DEG C and is maintained for 1.5 to 2.5 hours, the billet is controlled to be rolled to the thickness of a finished product plate, the final rolling temperature is controlled about 820 to 950 DEG C, and the steel plate is air cooled or is air cooled after being fast water cooled to 450 to 650 DEC C after the rolling.

Description

technical field [0001] The invention belongs to the field of low-alloy steel manufacturing, and relates to a high-temperature steel alloy with a room temperature yield strength greater than 460 MPa, a yield strength ratio less than 0.80, a high temperature yield strength of 600°C greater than 2 / 3 of the room temperature yield strength (ie ≥ 307 MPa), and good impact toughness. Strength refractory steel and method for its production. Background technique [0002] Ordinary construction steel, such as SN400 and SN490 steel in JIS standard, Q235 and Q345 in Chinese national standard, etc., the yield strength drops rapidly to less than 2 / 3 of its room temperature yield strength at a high temperature above 350 °C, and almost no at 600 °C. It has bearing capacity and cannot meet the design requirements of modern steel structure high-rise buildings. In order to improve the fire-resistant ability of steel structures, Japanese researchers proposed the concept of fire-resistant steel ...

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Problems solved by technology

The refractory steel provided by this patent has a lower strength level and a higher content of alloying elements

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