Crystallizer covering slag for continuous casting of auto sheet

Abstract

The invention provides crystallizer covering slag for continuous casting of an auto sheet. The covering slag comprises, by weight, 23%-40% of CaO, 8%-20% of BaO, 10%-20% of SiO2, 20%-35% of Al2O3, 2.5%-5.5% of Li2O, 3%-6% of F<->, 1%-2% of MgO and 1%-2% of C. The physical performance of the crystallizer covering slag can meet the requirements of the melting point of 1,000-1,150 DEG C, 1,300-DEG C viscosity of 0.3-0.5 Pa.s and 1,400-DEG C surface tension of 0.4-0.5 N / m, and has the advantages of being high in viscosity, large in surface tension, low in reactivity, good in lubricity and high in absorbing included slag. When the crystallizer covering slag is applied to the producing and casting process of auto sheet steel, the slag-inclusion occurrence rate of a continuous casting sheet billet of the auto sheet steel can be decreased and even eliminated, and the drawing speed can be increased to increase the production rate.

Description

technical field [0001] The invention belongs to the technical field of metallurgy, and in particular relates to auxiliary materials used in continuous casting processes, and more particularly relates to mold powder for continuous casting of automobile plates. Background technique [0002] Continuous casting mold slag is a kind of auxiliary functional material for steelmaking covering the surface of molten steel in the mold of continuous casting machine. The process controls the last process element of the surface quality of the slab. Automobile steel is a high-end product among steel products and an important symbol of a country's steel industry technology level. Due to the tight production rhythm of automobile steel, the amount of aluminum oxide inclusions in molten steel is often high. During casting, the amount of argon blowing at the nozzle is often increased to prevent the nozzle from being covered by Al. 2 o 3 The problem of inclusion clogging, and also want to incr...

AI Technical Summary

Problems solved by technology

Chinese patent CN102019382B discloses "low-sodium high-viscosity tin plate mold powder" and CN103128240A discloses "a low-carbon steel continuous casting mold powder", both by reducing Na in the mold powder 2 O content increases the surface tension of mold flux, but in these two patents SiO 2 The content is very high, respectively 44.1~46.1% and 40~44%, which is not suitable for the continuous casting production of automobile steel with high Al and Ti content

Patent CN104707959A discloses "a continuous casting mold flux for automobile panels", the matrix composition of which is Na 2 O≤0.25%, MgO0.5~4.5%, Fe 2 o 3 0.3~1.0%, Al 2 o 3 5~25%, Li 2 O0.5~6.5%, BaO0~16%, F - 5~9%, SiO 2 20~40%, C1~2%. On the whole, the mold flux of this invention has higher viscosity and surface tension, which is beneficial to reduce the incidence of slag inclusions in continuous casting slabs of automobile plates, but the SiO 2 The content is relatively high, which is 20~40%, so the low reactivity of the mold flux is still high. When continuous casting of automotive steel with high Al or Ti content, the mold flux needs to be further optimized

In addition, ultra-low carbon steel is a type of steel with poor thermal conductivity. In order to strengthen the cooling of the slab, mold slag is not expected to crystallize. F - The compounding amount is generally low, about 3 to 5%, and the F in the mold flux of this invention - The content is slightly high, 5~9%, and it is possible to form fluorine-containing crystals such as lance spar. It is not conducive to the lubrication of the billet when the electromagnetic hysteresis is used to implement high casting speed.

Images