Conticasting technology for feeding rare-earth wires into tundish

Abstract

A technology for feeding the rare-earth wire into conticasting tundish features that the molten steel flows from ladle into tundish and then into the crystallizer under the control of stopper, and the rare-earth wire comes into molen steel near the stopper in the tundish and is molten. Its advantages are uniform distribution of rare earth is molten steel, high effect on modifying sulfide, high rate of finished products and impact toughness, for conticast plate, and simple operation.

Description

1. Technical field [0001] The invention relates to a process for adding rare earth into liquid steel during continuous casting to improve steel properties, in particular to a process for feeding rare earth wires into a continuous casting tundish. 2. Background technology [0002] In addition to calcium and magnesium, the method of adding rare earth elements to steel has high requirements. This is mainly due to: 1) rare earth elements have a low ignition point, are easy to oxidize, and are easy to burn at high temperatures. In the process of steelmaking and pouring, they are easy to burn and lose in the air before entering the molten steel; Strong, when in contact with molten slag, it is easy to interact with the oxide components in the slag, and itself is oxidized and enters the slag. 3) The products formed by the action of rare earth elements added to molten steel and sulfur in steel, or rare earth elements dissolved in molten steel, will regenerate when they come into con...

AI Technical Summary

Problems solved by technology

(3) Post-addition process: rare earths mainly play the role of metamorphic inclusions in steel, and the recovery rate of rare earths is high, but the generated products cannot be removed basically, and the distribution of rare earths and sulfur in steel is uneven. The primary reason is the time of adding rare earths Too late, the rare earth metals do not have time to fully diffuse; at the same time, the rare earth inclusions formed do not have the dynamic conditions to float up, so a large number of rare earth inclusions exist in the steel

The analysis and test data show that the late addition process, although the rare earth in the steel can improve some properties and deteriorate the inclusions, but due to the defects in the distribution of the rare earth and sulfur, the inclusions cannot be removed, especially the microalloying effect of the rare earth is not fully developed. effect, which affects the application of this process in high-quality steel and pure steel

[0005] The process of feeding rare earth wires to the continuous casting crystallizer has the advantages of high recovery rate of rare earths, easy and stable and accurate control of the amount of rare earths added, but this method has the following disadvantages: (1) The time for adding rare earths is late, and the rare earths do not have time to fully diffuse in the crystallizer , and there is no kinetic condition that can make the inclusions float, so most of the rare earth reaction products remain in the steel and cannot be removed; (2) The uneven distribution of rare earth and sulfur on the billet section affects the process at high The application in high-quality steel and pure steel; (3) This method has a limit value requirement for the minimum thickness of the continuous casting slab, and the application on the middle slab will produce defects and cause the steel plate to be scrapped

For example, the converter plant of Nanjing Iron and Steel Group Co., Ltd. has been adding rare earth to the continuous casting slab by feeding rare earth wire to the crystallizer to improve the performance of the hot-rolled steel plate. However, in the continuous casting slab production, there are always a considerable amount of hot-rolled steel plate It was scrapped due to moiré and small spalled pits on the surface; there are still a large number of slag defects in the 1 / 4 range of the inner arc side of the medium plate continuous casting slab produced by this method

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