ESR Flux

Electro Slag Remelting (ESR) is a process of remelting and refining steel and other alloys for high-quality applications. ESR Flux material is an important component of this process, as it helps to purify the molten metal and control the solidification structure.

ESR Flux material is a mixture of various oxides, such as calcium oxide CaO , aluminum oxide Al2O3, and calcium fluoride CaF2 , that forms a molten slag layer on top of the metal pool during ESR. The slag layer acts as a medium for the electric current to pass through and heat up the metal electrode,

ESR Flux material also plays a key role in removing impurities and inclusions from the metal droplets that fall through the slag layer. The slag reacts with the impurities, such as sulfur, phosphorus, oxygen, and nitrogen, and traps them in the slag phase. The slag also filters out the non-metallic inclusions, such as oxides and sulfides, that may affect the mechanical properties and performance of the final product.

ESR Flux material influences the microstructure and crystallography of the solidified metal ingot. The slag affects the temperature gradient, cooling rate, and solute distribution in the metal pool, which in turn affect the nucleation and growth of grains and phases. The slag also modifies the surface tension and viscosity of the metal, which affect the shape and size of the metal droplets. The slag can also introduce alloying elements or modifiers into the metal, such as rare earth elements or titanium, to improve the characteristics of the final product.

ESR Flux material can be classified into different grades according to their composition, properties, and applications. For example, pre-melted Electro flux products are high-quality fluxes that have low moisture content and low content of heavy metals. They offer consistent composition and reproducible remelting results. Electro flux products of ELH (Extra Low Hydrogen) quality have even lower moisture content and are suitable for hydrogen-sensitive steel grades.

Application

ESR flux is used for remelting and refining steel and other alloys for high-quality applications in aircraft, thermal power stations, nuclear power plants, military technology and others1. Some examples of steel grades that can be produced with ESR flux are:

Stainless steels, such as CrNi60WTi, which can be used for the construction of nuclear power plants,

Tool steels, such as H13, D2, M2, S7, which can be used for making molds, dies, cutting tools and other wear-resistant parts.

High-speed steels, such as T1, M42, M35, which can be used for making drills, taps, milling cutters and other high-performance tools.

Super alloys, such as Inconel 718, Incoloy 825, Hastelloy C276, which can be used for making turbine blades, heat exchangers, corrosion-resistant components and other high-temperature applications.

These are just some examples of steel grades that can be produced with ESR flux. There are many more types and grades of steels and alloys that can benefit from the ESR process. The choice of ESR flux depends on the composition and properties of the metal alloy and the desired characteristics of the final product. ESR fluxes can be customized according to customers’ special steel/alloy grades.