Method for optimizing steel structure by adding nano particles into steel liquid

Abstract

The invention discloses a method for optimizing a steel structure by adding nano particles into steel liquid, which belongs to the field of ferrous metallurgy. The method comprises the following steps of: mixing and dispersing nano-powder and pure iron powder, wherein the mass percentage of the nano-powder is 1-40 percent, the mass percentage of the pure iron powder is 60-99 percent, and the average particle size of the nano-powder is 10-5,000 nm; under inert gas, sintering the mixture into a nano-powder stick by a hot-pressing technology, wherein a core material of the nano-powder stick is a steel stick, the outer layer of the nano-powder stick is provided with the mixture, the hot-pressing sintering pressure is 5-40 MPa, the sintering temperature is 1,000-1,400 DEG C, and the heat preservation time is 5-15 minutes; and inserting the nano-powder stick into the steel liquid of a steel ladle or a tundish, wherein the insertion depth of the nano-powder stick is 1 / 2-2 / 3 of the total depth of the steel liquid, and the nano-powder stick is driven by a mechanical hydraulic device to vibrate up and down or left and right. By the method, the nano particles can be effectively and uniformly dispersed and distributed in the steel liquid.

Description

technical field [0001] The invention belongs to the field of iron and steel metallurgy, and more specifically relates to a method for adding nanoparticles to molten steel to optimize steel structure. Background technique [0002] There are usually a large number of nano-second phase particles in steel. According to Yong Qilong's definition in the book "Second Phase in Iron and Steel Materials", the second phase in steel refers to the phase that is distributed in the matrix phase in a discontinuous state and cannot surround other phases in it. These nano-second phase particles have complex effects on the mechanical properties of steel due to their different types, sizes, shapes, distributions and volume fractions. [0003] The control and utilization of the second phase particles in steel has always been one of the hot issues concerned by metallurgists. The traditional idea is that the second phase particles in steel are often the cause of surface and internal defects of st...

AI Technical Summary

Problems solved by technology

This application adopts the method of deep deoxidation of aluminum in the smelting process, so that the deep deoxidation and deep desulfurization of molten steel are easy to realize, but its disadvantages are: on the one hand, the specific surface area of ​​nano-scale MgO and CaO powder is large, easy to agglomerate, The bulk density is small, so if you directly spray pure MgO and CaO powder (one or two) into molten steel without dispersion, it is very easy to agglomerate and cannot be dispersed evenly

However, since the preparation of additives is simply isostatic pressing, without sintering and other methods to make it into a completely dense state, its density is lower than that of molten steel, so it will float up soon and cannot be dispersed in molten steel.

[0012] To sum up, at present, there are mainly two ways to add nano powders into molten steel: one is to use carrier gas for injection, the disadvantage is that the carrier gas will make nano inclusions adhere to it, Therefore, it floats up to the slag-steel interface, is absorbed by the slag, and cannot play the role of refining the structure; the other is to use external force to instantly send nano-powder or massive nano-powder into the depth of molten steel (shot peening, Feeding wire, punching bag method, direct input method), its disadvantage is that because the density of nano powder or massive nano powder is lower than that of molten steel, it will quickly float to the interface of slag and steel, so that it cannot be dispersed in molten steel. Lost the effect of adding nano powder

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