A kind of 300mpa level hot-rolled smooth round refractory steel bar and its manufacturing method

Abstract

The invention provides a 300MPa level hot-rolled smooth round refractory steel bar and its manufacturing method, its weight percentage and chemical composition are: C: 0.16%-0.22%, Si: 0.20%-0.50%, Mn: 0.30%-0.60% , P: ≤0.03%, S: ≤0.03%, Cr: ≤0.35%, Mo: 0.20%~0.40%, the balance is Fe and unavoidable residual elements; the specific manufacturing methods are: molten steel smelting, continuous casting, continuous Billets are heated and steel bars are rolled. The method produces high-strength steel bars with refractory properties whose yield strength at 600°C is not lower than 2 / 3 of the yield strength at room temperature through composition optimization design and steelmaking, refining, continuous casting and steel rolling process optimization.

Description

technical field [0001] The invention belongs to the technical field of steel preparation, and in particular relates to a 300MPa grade hot-rolled smooth round refractory steel bar and a manufacturing method thereof. Background technique [0002] At present, the development of super high-rise buildings in my country began in 1990. The period from 1990 to 2007 is the initial period of super high-rise buildings. The period from 2008 to 2012 is the period of rapid development of super high-rise buildings. The period from 2013 to 2018 is the period of prosperity of super high-rise buildings. Based on the height, the super high-rise buildings are divided into the following four sections: 250-300m, 300-400m, 400-500m and above 500m. Before 2012, a total of 94 super high-rise buildings were built in my country, and the number of super high-rise buildings with a height of 250-300m was the largest, accounting for about 59% of the total number of buildings; 20% of the total. From 2013 ...

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Problems solved by technology

When the temperature of ordinary construction steel rises above 350°C, the yield strength decreases to 2 / 3 or even lower than that at room temperature; when the temperature reaches 600°C, the yield strength drops significantly, only 1 / 3 of the yield strength at room temperature When the temperature rises to about 700°C, the yield strength decreases by about 50MPa, which is far from meeting the fire resistance of buildings.

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