Pouring slag for continuously casting cast steel plate (CSP) sheet billet high-carbon steel

Abstract

The invention discloses pouring slag for continuously casting cast steel plate (CSP) sheet billet high-carbon steel. During the continuous casting of the CSP sheet billet high-carbon steel, phenomena of binding cold steel, clotting pouring slag and slagging badly do not occur basically when silicon iron is used; the pouring slag has low alkalinity and proper viscosity; after the silicon iron is oxidized quickly, the silicon iron and other components of the pouring slag form acidic slag with alkalinity of 0.5 to 0.7 quickly; and under an acidic slag system, a network limiting body, namely silicon dioxide has high content, so that the viscosity of liquid slag formed by the pouring slag which uses a large number of fusing agent materials such as sodium fluoride, flousper powder, white alkali, cryolite and the like is not ultralow, the liquid slag forms uniform slag membranes between a primary solidification billet shell and the wall of a crystallizer and has long viscous time, and stable, continuous and good lubricating effect is provided during pouring of the CSP high-carbon steel.

Description

technical field [0001] The invention belongs to the technical field of steelmaking auxiliary materials, and in particular relates to a casting slag for continuous casting of CSP thin slab high-carbon steel. technical background [0002] CSP thin slab continuous casting is characterized by its high efficiency and short process, and represents the most advanced strip steel production technology. And other steel mills have introduced multiple sets of CSP continuous casting production lines. [0003] In CSP thin slab continuous casting, casting failure is a relatively common type of vicious accident, which has a huge impact on the continuous casting production line: it directly causes unplanned shutdown of casting, seriously affects the production rhythm, and brings great waste of manpower and material resources and economy to the steel plant. benefit loss. Therefore, solving the failure of casting is an important problem that all CSP continuous casting manufacturers need to s...

AI Technical Summary

Problems solved by technology

In general, the general-purpose pouring slag has a faster slag formation speed, and the formed liquid slag has a moderate alkalinity of about 0.8, which can meet the pouring requirements of most models and most steel types, including CSP with high pouring temperature. It is not a big problem when using low carbon and medium carbon, but CSP high carbon steel continuous casting is special, its casting speed is high, the amount of liquid slag required per unit time is large, and the liquidus temperature of high carbon steel is relatively low 1. When the general general pouring slag is used, due to the low temperature of molten steel, the slag is slow to melt, and it is easy to fail to break out when the demand is large and the supply of liquid slag is small;

[0008] 2. The characteristics of high-carbon steel (with a carbon content of 0.26-1%) lead to the failure of CSP continuous casting

First of all, the liquidus temperature of high-carbon steel is usually much lower than that of medium-carbon steel and low-carbon steel. Insufficient heating and calorific value can easily cause molten steel to freeze steel, which will make it difficult to judge on-site operation and cause casting failure; Compared with the former, the casting slag should have lower basicity, melting point and proper viscosity

The lower basicity and melting point are to ensure the good lubricating properties of the casting slag, and the proper viscosity means that the viscosity cannot be too high or too low, because for high carbon steel, when the casting slag viscosity is too low It is easy to roll slag and breakout, and when the viscosity of pouring slag is too high, it may cause a steel breakout accident due to poor lubrication

This once again shows that general-purpose casting slag cannot meet the requirements of CSP thin slab high carbon steel continuous casting

[0009] The domestic publication number is CN1257764's patent "pre-melted heating slag" which cannot meet the needs of CSP thin slab continuous casting. In order to make the final slag close to the physical and chemical properties of the general medium-carbon steel mold slag, a higher basicity (1.1-1.3) is used to solve the problems of carbon steel cracks in the slab. This patented technology has been used in slabs for many years The practice of continuous casting of carbon steel in the slab has found that it has an excellent effect on controlling carbon cracks in the slab and improving the surface quality of the slab

However, the slag forming speed provided by the patent is still too slow for CSP continuous casting, and the heat transfer ability is strong and the lubrication effect is poor for high carbon steel, so it is not suitable for CSP High carbon steel continuous casting slag