Abstract

Developing a technology for introducing alloy addition to liquid steel during the course of continuous casting process seems to be an interesting approach to enhancing the steelmaking process, especially as the effective introduction of micro-additives or non-metallic inclusion modifiers to the liquid steel is the key to the production of the highest-quality steel. This paper presents the results of investigation describing the process of liquid steel chemical homogenisation in the two-strand slab tundish. The alloy was fed to liquid steel by pulse-step method. Five tundish equipment variants with different flow control devices and alloy addition feeding positions were considered. The paper includes fields of liquid steel flow, alloy concentration vs. time curves, dimensionless mixing time, minimum time values and alloy concentration deviations at tundish outlets. The results pointed much more effectively with liquid steel mixing nickel than aluminium. For aluminium obtaining a 95% chemical homogenisation level requires three-fold more time. Moreover, it is definitely beneficial for chemical homogenisation to initiate the alloying process simultaneously in two sites. This procedure generates, among others, the least alloy deviation of concentration at tundish outlets.

Highlights

  • This paper presents the results of computer simulations of feeding the slight alloy addition to liquid steel by pulsestep method during casting of slabs through two-strand, trough-shaped tundish

  • On the basis of computer simulations, steel flow fields were developed that reflect the hydrodynamic conditions for the two considered tundish equipment

  • The global hydrodynamic view shows some recirculation zones progressed from pouring zone to tundish outlets

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Summary

Introduction

The continuous steel casting (CSC) process is based on the flow of liquid steel between the ladle, the tundish, the mould and the secondary cooling zone. Before the liquid steel begins to solidify, it is poured from the ladle into the tundish, where it stays for a certain time. The primary function of the tundish is to protect the liquid steel against secondary oxidation and to maintain the required temperature of the cast steel grade. The tundish may support liquid steel refining processes through non-metallic inclusions flotation or Ca treatment [1]. The basic and additional functions can be assisted by modifying the hydrodynamic conditions using flow control devices (FCDs). FCDs are mounted in the internal working volume of the tundish. FCDs contain dams, weirs, dams with holes, gas-permeable barriers, subflux turbulence controllers and electromagnetic stirrers [4,5,6,7,8,9,10,11,12,13]

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