Electrode manufacture for the remelting processes

Mitchell, A.

doi:10.1080/03019233.2020.1855690

Cited by 5 publications

(2 citation statements)

References 33 publications

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“…The cracks inflict major defects on the integrity of the VAR process and the final VAR ingot. It is interesting to note that Mitchell has drawn attention to the several shortcomings of electrodes in addition to their bifilm problems [5].…”

Section: The Vim Process and Its Limitationsmentioning

confidence: 99%

A Future for Vacuum Arc Remelting and Electroslag Remelting—A Critical Perspective

Campbell

2023

Metals

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In the secondary metals refining processes, vacuum arc remelting (VAR) and electroslag remelting (ESR), the consumable electrode is commonly produced by vacuum induction melting (VIM) which employs the regrettably primitive casting technique of simply pouring into the open top of the mold. Despite the vacuum, the resulting oxidizing conditions and the immensely powerful turbulence accompanying the top-pouring of the electrode is now known to create a substantial density of serious cracks. The cracks in the cast electrode are bifilms (double oxide films), which in turn are proposed to be responsible for the major faults of the VAR ingot, including undetectable, horizontal macroscopic cracks, white spots (clean and dirty varieties) and in-fallen crown. The remedial action to solve all these issues at a stroke is the provision of a counter-gravity cast electrode, cast in air or vacuum, or provision of any similar electrode substantially free from bifilm defects. The ESR process is also described, explaining the reasons for its significantly reduced sensitivity to the top-poured VIM electrode, but indicating that with an improved electrode, this already nearly reliable process has the potential for perfect reliability. The target of this critical overview is an assessment of the potential of these secondary refining processes to produce, for the first time, effectively defect-free metals, metals we can trust.

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Section: The Vim Process and Its Limitationsmentioning

confidence: 99%

A Future for Vacuum Arc Remelting and Electroslag Remelting—A Critical Perspective

Campbell

2023

Metals

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“…At the electrode tip, with the rapid increase in temperature, parts of inclusions decomposed into oxygen and deoxidants, and then removed through slag-steel reactions at the metal-slag interface of the tip, droplet, and steel-pool. [8,9] Noticeably, there were also newly formed inclusions caused by the entrainment of slag and the reoxidation during remelting, [10][11][12] which would reduce the cleanliness of the steel. Burja [13] studied the remelting of the H11 tool steel in the slag composed of CaF 2 , CaO, and Al 2 O 3 as well as very low contents of MgO and SiO 2 and found that the number density and the area fraction of nonmetallic inclusions in the steel decreased and that inclusions of MnS, SiO 2 , and MgO were strongly reduced.…”

Section: Introductionmentioning

confidence: 99%

Evolution of Nonmetallic Inclusions during the Electroslag Remelting Process

Wen

Ren

Zhang

et al. 2021

steel research int.

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The evolution of inclusions during the electroslag remelting (ESR) process, especially the inclusions in droplets is investigated by an industrial trial which remelts a plain carbon steel billet in the slag of CaF2–Al2O3–CaO–MgO. Results show that oxide inclusions change from SiO2–MnO to Al2O3–MnO during the ESR process. The transfer of aluminum from the slag to the steel increases the aluminum content in the steel and causes the reaction between (MnO), (SiO2) in inclusions with the [Al] in the steel to generate (Al2O3) inclusions. Thermodynamic results show that inclusion evolution is mainly influenced by the temperature and the total Al content in the steel. With the increase in temperature at the electrode tip, the MnO content in inclusions increases rapidly. Meanwhile, as the aluminum transfers from the slag to the steel, the Al2O3 inclusion increases clearly with the corresponding decrease in MnO and SiO2 inclusions. In addition, from the electrode to the ingot, the number density of inclusions decreases from 208.82 to 33.49 # mm−2, whereas the average size increases from 3.79 to 5.76 μm. Both the chemical modification and the physical absorption of slag mainly occur at the liquid film and droplet stage.

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Study on the Molten Pool Behavior, Solidification Structure, and Inclusion Distribution in an Industrial Vacuum Arc Remelted Nickel-Based Superalloy

Zhao

Yang

et al. 2023

Metall Mater Trans B

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Electrode manufacture for the remelting processes

Cited by 5 publications

References 33 publications

A Future for Vacuum Arc Remelting and Electroslag Remelting—A Critical Perspective

A Future for Vacuum Arc Remelting and Electroslag Remelting—A Critical Perspective

Evolution of Nonmetallic Inclusions during the Electroslag Remelting Process

Study on the Molten Pool Behavior, Solidification Structure, and Inclusion Distribution in an Industrial Vacuum Arc Remelted Nickel-Based Superalloy

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