400-MPa-grade fine-grain hot rolled steel bar and manufacturing process thereof

Abstract

The invention discloses a 400-MPa-grade fine-grain hot rolled steel bar and a manufacturing process thereof, and belongs to the field of hot-rolled steel bar production. The steel bar comprises the following components in percentage by mass: 0.20-0.25% of C, 0.3-0.8% of Si, 1.2-1.6% of Mn, 0.01-0.04% of P, 0.01-0.04% of S, 0.005-0.03% of Ti, 0.001-0.08 % of Cr, 0.0001-0.008% of V, 0.0001-0.008% ofNb, 0.0001-0.008% of Al, 0.01-0.02% of O, 0.003-0.01% of N, and the balance Fe and inevitable impurities; and the steel bar further comprises manganese silicate inclusions, titanium oxide manganese sulfide multiphase inclusions, manganese sulfide inclusions, and other inevitable inclusions. The manufacturing process comprises the following steps of smelting molten steel, heating a continuous casting billet, and rolling a steel bar. According to the process, by combining optimization of the components and the inclusions with smelting continuous casting and rolling improvement as well as the inclusion induced fine grain strengthening mechanism, the strength of the steel bar is improved, the addition of precious alloy elements is reduced, and low-cost and high-quality production of the hot-rolled steel bar is achieved.

Description

technical field [0001] The invention belongs to the technical field of hot-rolled steel bar production, and particularly relates to a 400MPa-grade fine-grain hot-rolled steel bar and a production process thereof. Background technique [0002] With the rapid development of my country's industrialization and urbanization, the demand for high-quality construction steel in the fields of infrastructure construction and construction has increased significantly. In order to further improve the quality of construction steel, promote energy conservation and emission reduction, eliminate outdated production capacity, and meet the needs of construction, transportation, engineering and other fields, my country began to implement a new national standard for hot-rolled ribbed steel bars GB / T 1499.2-2018. The new standard puts forward new requirements for rebar production process, metallographic structure and strength level. At present, improving the strength of steel bars is mainly achi...

AI Technical Summary

Problems solved by technology

This method solves the problems of adding a large amount of precious alloy elements or the difficulty of controlled rolling production in the current production of steel bars, and realizes the refinement of steel bar grain size and the improvement of strength under the conditions of reducing alloy costs and simplifying the rolling process.

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