Experimental investigation of recovery and efficiency of calcium addition through cored wire in steel melt at Visakhapatnam Steel Plant

Abstract

Samples from calcium-treated liquid steel at Visakhapatnam Steel Plant (VSP), Visakhapatnam are studied under scanning electron microscope to understand the inclusion evolution under various operating parameters. The compositions of inclusions are plotted in ternary Ca-Al-S diagram to evaluate the efficiency of inclusion modification and stable casting operation. Process parameters such as amount of calcium addition, bath superheat, and the speed of wire injection are studied for calcium treatment of steel. Both CaFe and CaSi addition are studied, and calcium recovery for CaFe addition is always found to be less than CaSi addition for the same operating conditions. For CaSi addition, the recommended ranges in terms of bath superheat, wire speed, and the amount of calcium addition are identified for the operating conditions studied for VSP, Visakhapatnam.

Effect of Types of Calcium‐Containing Cored Wires on the Inclusion Modification by Calcium Treatment

“…[19] The calcium treatment is usually carried out by the injection of calcium-containing cored wires, which have several types in the industrial production, including the Ca wire, the AlCa wire, the SiCa wire, and so on. [20][21][22] Many investigations on the modification of inclusions by calcium treatment have been conducted. It was found by Geldenhuis [23] that the transformation order of Al 2 O 3 inclusions after calcium treatment was Al 2 O 3 !…”

“…[ 19 ] The calcium treatment is usually carried out by the injection of calcium‐containing cored wires, which have several types in the industrial production, including the Ca wire, the AlCa wire, the SiCa wire, and so on. [ 20–22 ]…”

“…Besides the theoretical research, the precise calcium treatment also depended on the industrial practice‐related parameters, such as melting position of calcium core wire [ 34 ] and model of cored wire, [ 35 ] and it was found to decrease with the increase of the feeding speed of calcium containing wires in the industrial production. [ 21 ] In addition, different calcium containing wires would be used for calcium treatment in the industrial production, which should also have an influence on the calcium yield. It was found that calcium yield of CaFe wire addition is always lower than SiCa wire addition in industrial practice.…”

“…It was found that calcium yield of CaFe wire addition is always lower than SiCa wire addition in industrial practice. [ 36 ] However, the detailed influencing degree and mechanism were not so clear. In the current work, laboratory experiments on the calcium treatment using different calcium containing wires were carried out to investigate the effect of the type of calcium‐containing cored wires on the calcium yield and the modification of inclusions by calcium treatment.…”

Modification of oxide inclusions in calcium-treated Al-killed high sulphur steels

“…Inclusions in steels are very harmful as they not only deteriorate the mechanical properties such as fatigue and fracture strength of the final product, but also disrupt the continuous casting by nozzle clogging [2][3][4] . Hence, modification of inclusions to transform them to liquid inclusions reduces nozzle clogging problems in steel industry [5][6][7][8][9] . The main objective of inclusion modification is to transform solid inclusions to liquid inclusions by changing the chemical and phase composition in aluminium killed steel [10][11][12] .…”