A kind of processing method of high-strength steel bar for construction

Abstract

The invention discloses a method for machining a high-strength steel bar for a building. The method comprises the following steps of 1, compounding components of the steel bar, wherein the steel bar comprises 0.25%-0.35% of C, 0.30%-0.40% of Si, 0.9%-1.2% of Mn, 0.4%-0.8% of Cr, 5%-7% of Ni, 0.5%-0.6% of Co, less than or equal to 0.03% of P, less than or equal to 0.03% of S and the balance Fe; 2,mixing and melting the components into molten steel, mixing IrO2-NiO composite powder into the molten steel, stirring a mixture completely till the mixture is uniform, and conducting casting, so thata steel billet is obtained; 3, after the steel billet is preheated and subjected to heat homogenization, sequentially conducting rough rolling, medium rolling and finish rolling, so that the finish-rolling steel bar is obtained; 4, putting the steel bar into a vacuum heat treatment furnace for heating and tempering; 5, conducting plasma carburization on the surface of the steel bar; and 6, removing a thin layer which is not corrosion-resistant from the surface of the steel bar, so that the high-strength high-corrosion-resistance steel bar is obtained. According to the method, the IrO2-NiO composite powder is added to the molten steel before casting; in the casting process, the molten steel can rely on activity point location heterogeneous nucleation of the IrO2-NiO composite powder easily;the steel billet obtained after casting is fine in crystalline grain; the IrO2-NiO composite powder cannot be mixed into crystal lattices through solid solution easily; and the effect that a second phase is reinforced is achieved.

Description

technical field [0001] The invention relates to the technical field of building materials, in particular to a method for processing high-strength steel bars for building. Background technique [0002] The meaning of high-strength steel bar refers to the threaded steel bar whose yield strength reaches or exceeds 400MPa in its mechanical properties. Rebar is the product with the largest number of single varieties of steel in my country. Compared with ordinary 335MPa grade rebar, high-strength rebar has the characteristics of high strength / price ratio and excellent comprehensive performance. [0003] At present, high-strength steel bars have been widely used abroad. Although the United States, Japan, Russia and other countries have retained 335MPa steel bars, they are actively using high-strength steel bars. Among them, the United States stipulates that the highest yield strength steel bars are 550MPa, Japan is 490MPa, and Russia has reached 600MPa, Britain and Germany have al...

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Problems solved by technology

[0004] Generally speaking, with the increase of strength, the plasticity, toughness and impact resistance of steel bars all decrease, but in construction, steel bars are required to have high strength and good plasticity at the same time, which restricts the further improvement of steel bar strength; The rust on the surface of the steel bar causes local scale-like corrosion, and the shell can fall off. This kind of steel bar cannot meet the requirements of the national standard. Therefore, the rust prevention of the steel bar surface is also a very important issue for high-strength steel bars. Most of the anti-rust measures on the surface of the steel bar are surface bluing, adding Cr, Ni elements, etc., but the bluing is to form a thin and dense film on the surface of the steel bar. After adding alloying elements Cr and Ni, the composition of the steel bar will usually be changed to affect its overall performance, and the production cost will increase accordingly, so it is not suitable for a wide range of applications

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