Macrosegregation in Rotated Remelted Ingots

Sindo Kou, David R Poirier, Merton C. Flemings

Research output: Contribution to journalArticle

64 Citations (Scopus)

Abstract

A computer model is presented for predicting macrosegregation in rotated electroslag or vacuum arc remelted ingots. Sample calculations of segregation are carried out for ingots of the model alloy Sn-12 pet Pb in which the liquid density increases during solidification and for two hypothetical alloys; in one, the liquid density decreases during solidification, and in the other, liquid density first increases and then decreases during solidification. In alloys such as Sn-Pb in which liquid density increases during solidification, segregation is positive at the ingot centerline and if solidification is sufficiently slow, "freckles" form near the centerline. Positive segregation and freckles are found at the outer periphery of the ingot when liquid density decreases during solidification. Positive segregation and freckles are found at midradius when liquid density first increases and then decreases during solidification, and when the solidus isotherm changes shape abruptly at midradius (with density increasing during solidification). Ingot rotation, by introducing a radial component to the force field, alters interdendritic flow behavior and therefore macrosegregation. Modest rotation speeds eliminate "freckles" and reduce macrosegregation in all modeling studies conducted. Greater rotational speeds can accentuate the segregation. Experiments were conducted on simulated remelted ingots of Sn-Pb alloy. The ingots were 8 cm diam, rotated at speeds up to 119 rpm and solidified at rates from 5.3 × 10-3 to 1.36 × 10-2 cm/s. Segregation behavior obtained agrees qualitatively and quantitatively with theory.

Original languageEnglish (US)
Pages (from-to)711-719
Number of pages9
JournalMetallurgical Transactions B
Volume9
Issue number4
DOIs
StatePublished - Dec 1978

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ingots
Ingots
Density of liquids
solidification
Solidification
liquids
solidus
field theory (physics)
Isotherms
isotherms
arcs
Vacuum
vacuum

ASJC Scopus subject areas

  • Condensed Matter Physics
  • Metals and Alloys
  • Materials Chemistry
  • Mechanics of Materials
  • Engineering(all)

Cite this

Macrosegregation in Rotated Remelted Ingots. / Kou, Sindo; Poirier, David R; Flemings, Merton C.

In: Metallurgical Transactions B, Vol. 9, No. 4, 12.1978, p. 711-719.

Research output: Contribution to journalArticle

Kou, Sindo ; Poirier, David R ; Flemings, Merton C. / Macrosegregation in Rotated Remelted Ingots. In: Metallurgical Transactions B. 1978 ; Vol. 9, No. 4. pp. 711-719.
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