A 400mpa grade fine-grained hot-rolled steel bar and its production process

Abstract

A 400 MPa-grade fine-grain hot rolled steel bar and a manufacturing process therefor, which relate to the field of hot-rolled steel bar production. The steel bar comprises the following components in mass percentage: 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% of Nb, 0.0001-0.008% of Al, 0.01-0.02% of O, and 0.003-0.01% of N, the rest being Fe and inevitable impurities. The described steel bar further comprises manganese silicate inclusions, titanium oxide manganese sulfide multiphase inclusions, manganese sulfide inclusions and other inevitable inclusions. The manufacturing process comprises: molten steel smelting, continuous casting, continuous cast billet heating and steel bar rolling. According to the described method, by combining the optimization of the components and inclusions with smelting, continuous casting and rolling improvement as well as an inclusion induced fine grain strengthening mechanism, the strength of the steel bar is improved, the amount of precious alloy elements added is reduced, and the low-cost and high-quality production of a hot-rolled steel bar is achieved.

Description

technical field [0001] The invention belongs to the technical field of hot-rolled steel bar production, and in particular relates to a 400MPa fine-grained 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 backward production capacity, and meet the needs of construction, transportation, engineering and other fields, my country began to implement the new national standard for hot-rolled ribbed steel bars GB / T 1499.2-2018. The new standard puts forward new requirements for the production process, metallographic structure and strength level of steel bars. At present, increasing the strength of steel bars is...

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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