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Pre-melted slags for the ESR-Process


AKF is a pre-melted mixture based on alumina, lime and fluorspar for the electroslag remelting process. Based on the phase diagram C-A-F, which is typical for ESR slags, we offer numerous standardized compositions due to the different steel grades and correspondingly varying requirements for the ESR slag. In addition, we are prepared to realize individual slag compositions upon customer request and to offer small quantities required for experimental purposes.


Main ingredients: Al2O3, CaO, CaF2

Bulk density: 1.3 to 1.7 kg / dm



For special steel grades, the processes of primary and secondary metallurgy are not sufficient. In such cases, tertiary treatment by remelting and controlled crystallization is necessary. These processes include the electroslag remelting (ESR) process, in which remelting of the steel takes place under a protective, metallurgically active slag layer. The heat required to melt the steel is supplied by the electrical resistance of the slag in the energized state. As the molten steel droplets sink through the slag, interfacial reactions such as desulfurization, diffusion deoxidation and deposition of already formed nonmetallic inclusions are promoted due to the large surface area. A largely defect-free microstructure with significantly improved technological properties is produced, while block segregation and non-metallic inclusions are minimized. AKF is normally used in the so-called cold start, with a specific consumption of about 20 kg/ton of steel.



  • Reduction of non-metallic inclusions (sulfides and oxides) in the steel.

  • Improvement of technological properties of the steel

  • Minimization of ingot segregation

  • Adjustment of electrical conductivity due to variable composition

  • Pre-melting results in the following advantages:

    • easy, complete liquefaction of the slag

    • lower tendency to absorb moisture (lower risk of hydrogen pick-up)

    • process reliability due to constant and uniform composition

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