A high-efficiency production process of high aluminum alloy structural round steel

Abstract

The invention relates to a production method of round steel, in particular to an efficient production process of high aluminum-alloy-content structure round steel. Al accounts for 0.70-1.20% in the round steel by weight. The preparation method comprises the converter smelting process, the LF external refining process, the VD furnace vacuum refining process, the square bloom continuous casting process and the rolling process. The high aluminum-alloy-content structure round steel produced through the method is low in cost, high in purity and good in castability, the adsorption rate of aluminum can be higher than 95%, calcium treatment is not needed, sequence casting of 12-15 times can be achieved, the production efficiency is greatly improved, the surface quality of the round steel is high, and the technical problems of high aluminum-alloy-content structure round steel produced in the prior art that the continuous castability is poor, nodulation occurs easily, the adsorption rate of aluminum is low, the yield is unstable, the purity is low, the surface quality of the round steel is low and the quality is unstable are solved.

Description

technical field [0001] The invention relates to a steel production method, in particular to a high-efficiency production process for round steel with high aluminum alloy structure. Background technique [0002] The aluminum content of high aluminum alloy structural steel is extremely high, as high as 0.70-1.20%. It usually belongs to the category of aluminum-containing nitrided steel. After nitriding treatment, an aluminum nitride layer is formed in the nitrided layer of the steel. According to the dispersion of aluminum nitride Hardening can improve the surface hardness and strength of steel, so as to obtain hard, wear-resistant and corrosion-resistant properties. It is widely used in the aviation industry, conventional weapons and machinery manufacturing industries, such as tube blank engine gas steel sleeves, screw rods and sleeves of injection molding machines. Parts with special requirements such as barrels. The domestic and foreign annual demand of the injection moldi...

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Problems solved by technology

[0003] Years of production practice at the site shows that when the aluminum content of conventional steel reaches above 0.025%, the nozzle is easy to be blocked during continuous casting, while the aluminum content of high aluminum alloy structural steel is about 40 times that of conventional cold heading steel, which is currently the most One of the steel types that are difficult to continuously cast, because aluminum is extremely easy to oxidize, has a low melting point (660°C), and a small specific gravity (2.68g / cm 3 ) and other characteristics, resulting in the difficulty of adding aluminum to high aluminum alloy structural steel during smelting, and the yield is very unstable; at the same time, during the production process of high aluminum alloy steel, silicon oxide in slag is easy to reduce, aluminum in molten steel is easy to oxidize, silicon 1. The aluminum composition fluctuates greatly, the composition control is more difficult, and the molten steel is prone to secondary oxidation, and some oxides fail to float up and stay in the molten steel, which will cause blockage of the nozzle and cause flocculation, which will affect the quality of continuous pouring and steel cause great harm

[0004] Since the 21st century, the domestic production of high aluminum alloy structural steel usually adopts the electric furnace→die casting process, and some manufacturers even adopt the process technology of electroslag remelting, the labor productivity and finished product rate are relatively low, and the product quality is relatively poor

Recently, relevant domestic manufacturers have begun to gradually adopt electric furnace→LF refining→RH vacuum refining→continuous casting instead of electric furnace→die casting. In the stage of mass production, there are still some technical problems that are difficult to break through: ① Nodules are prone to occur in the continuous casting process, and the number of continuous casting furnaces is about 5 furnaces; ② The yield of aluminum is unstable, usually only 75% or so; ③The purity of the wire rod is not high, and the content and type of non-metallic inclusions, gas content, etc. appear to exceed the standard; ④The composition of silicon and aluminum fluctuates greatly, and it is difficult to control the composition; The quality is extremely unstable, therefore, these technical problems have greatly troubled the manufacturers of high aluminum alloy structural steel

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