A recently developed criterion for A-segregation in steel ingots and castings, based on a dimensionless Rayleigh number, is applied to case studies of two steel ingots. In both cases, experimentally obtained locations of A-segregation are correlated against Rayleigh numbers predicted through casting simulations. It is found that the value of 17±8 previously reported as the critical value for the Rayleigh criterion agrees well with the results of these case studies, but that 6 is an appropriate critical value if a conservative lower bound is sought. Limitations and sources of sensitivity in the application of the criterion are highlighted.
FlemingsM: ‘Solidi_cation processing’, 1974, New York, McGraw-Hill.
2.
TaylorH, FlemingsM and WulffJ: ‘Foundry engineering’; 1959, New York, Wiley.
3.
MarburgE: ‘Accelerated solidification in ingots: its inuence on ingot soundness’, J. Met., 1953, 157–172.
4.
MaidornC and BlindB: ‘Solidification and segregation in heavy forging ingots’, Nucl. Eng. Des., 1985, 84, 285–296.
5.
DruceS: ‘Investigation of the homogeneity of chemical composition and mechanical properties in a large A508 class 3 steel pressure vessel forging’, Vol. AERE - R9581, 1979.
6.
BethmontM, FrundJ.-M, HoussinB and SoulatP: ‘The toughness of irradiated pressure water reactor (PWR) vessel shell rings and the effect of segregation zones’, in‘Effects of radiation on materials: 17th International Symposium’, (ed. GellesD et al.), ASTM STP 1270, 320–330; 1996, ASTM.
7.
SoulatP, HoussinB, BocquetP and BethmontM: ‘Analysis of radiation embrittlement results from a French forging examined in the second phase of an IAEA-coordinated research program’, in‘Radiation embrittlement of nuclear reactor pressure vessel steels: an international review’, (ed. SteeleL et al.), ASTM STP 1170, 249–265; 1993, ASTM.
8.
TorabiM, KotasP and BeckermannC: ‘Rayleigh number criterion for formation of A-Segregates in steel castings and ingots’, Metall. Mater. Trans. A, 2013, 44A, 4266–4281.
9.
BeckermannC, GuJ and BoettingerW: ‘Development of a freckle predictor via Rayleigh number method for single-crystal nickel-base superalloy castings’, Metall. Mater. Trans. A, 2000, 31A, 2545–2557.
10.
RamirezJ and BeckermannC: ‘Evaluation of a Rayleigh-number-based freckle criterion for Pb-Sn alloys and Ni-Base superalloys’, Metall. Mater. Trans. A, 2003, 34A, 1525–1536.
11.
WorsterM: ‘Instabilities of the liquid and mushy regions during solidification of alloys’, J. Fluid Mech., 1992, 237, 649–669.
12.
SuzukiK and MiyamotoT: ‘Inuence of alloying elements on the formation of ‘A’ segregates in steel ingot’,Trans. ISIJ, 1980, 20, 377–383.
13.
YamadaH, SakuraiT and TakenouchiT: ‘Critical conditions for the formation of ‘A’ segregation in forging ingots’, ISIJ, 1989, 75, 97–104.
14.
PollockT and MurphyW: ‘The breakdown of single-crystal solidification in high refractory nickel-base alloys’, Metall. Mater. Trans. A, 1996, 27A, 1081–1094.
15.
CopleyS, GiameiA, JohnsonS and HornbeckerM: ‘The Origin of freckles in unidirectionally solidified castings’, Metall. Trans., 1970, 1, 2193–2204.
