ESR metal benefits

The reliability of modern steel structures and machinery is largely determined by the properties of the materials used. The main ones are steel and alloys, made predominantly by pyrometallurgy methods that involves solidification of a melt to produce semi-finished or ready product. While any multicomponent alloy (including steel) is solidifying the inevitable segregation of their components along an ingot height and cross section occurs. This is the general rule: the bigger cross-section and volume of solidified metal we have, the worse quality of an ingot we will receive. The cross section of a continuously cast billet is usually less than of a forging ingot, that is positive, concerning of the thesis above, however, a high speed of a billet withdrawing (because of tight limits of the steel castability that is poured from unheated ladle) leads to reduction of the renewal of metal volumes, which are adjacent to the solidification front and to restriction in hot topping. So, the appearance of both the segregation and shrinkage defects is possible.

The essence of the electroslag process is remelting of a metal of a consumable electrode due to heat releasing by the electric current passing through the slag bath. As a result, the heat has been generated at the contact line between electrodes and the slag. The tip of the consumable electrode melts forming droplets. These droplets fall down by gravity, pass through the slag layer and form a metal bath. The process is organised in a water-cooled copper mould, where metal ingot is forms, and the bath itself is constantly updated by the feeding of the metal from the electrode.

Due to the gradual and slow (compared to other casting processes) applying metal to the mould, the ESR ingot is formed in a high temperature gradient and constant renewal of the solidifying melt, which creates conditions for the growth of dense dendritic structure. High chemical macroscopically ESR metal due primarily to its dendritic structure. In addition, passing the metal through the slag layer is cleaned from sulfur and non-metallic inclusions.

Because of this, the metal electroslag remelting, has significant advantages in providing key indicators of quality with the ability to control the solidification up to the organization to unidirectional crystallization of the most advanced modern processes of ESR (ESR DC, ESR LM). The rate of formation of the ESR ingot during solidification rate determined by the cross section of the ingot and the rate of melting of the electrode (or the supply of liquid metal) resulting in an effective makeup shrinkage and shrinkage porosity ingot stripped. High density metal ESR combined with macro and mikrochistotoy, the uniformity of the chemical composition and the specific structure of dendritic growth provide a high level of mechanical properties, distinguishing feature is a unique combination of high strength and ductility. Due to dense dendritic structure metal ESR shows a unique combination of mechanical and service (high wear resistance, higher temperature resistance, etc.) properties.

Recently, the decisive argument in favor of the use of electroslag remelting in engineering has become a significantly higher yield. For large ingots expensive alloy steels (since the mass of the ingot 50 tons) ESR is more advantageous due to the minimum head and bottom trim, high-quality surface.

In summary it can be argued that the process of the ESR provides:

  • high speed curing in water-cooled mould.
  • constant updating of the liquid metal bath.
  • consistent slow formation of a dense ingot, wherein:
  • no shrinkage defects;
  • dendritic structure is uniform over the cross section and the height of the ingot;
  • ensure the high ductility and toughness of the metal at the same time.

a significantly higher metal yield in comparison with the ingot mould to diffuse.