20 12,, 59 q r Fig.2 [3] Fig.3 1cm Fig.2 Schematic of experimental apparatus for measuring interfacial thermal resistance. Fig.3 Surface morphol

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1 58 *1, *1, * 2 Mechanism of Heat Transfer through Mold Flux in Continuous Casting Mold By Hiroyuki Shibata, Shin-ya Kitamura and Hiromichi Ohta 1 K.C.Mills and A.B.Fox [1] [2] Fig.1 q c q r q t q t = q c + q r (1) q c Fig.1 Schematic of temperature distribution and resistances to heat transfer across mold flux film consisting of crystalline and molten layers. (R FLUX ) (R INT ) *1 *2

1 q c q r q t q t = q c + q r (1) q c Fig.

2 20 12,, 59 q r Fig.2 [3] Fig.3 1cm Fig.2 Schematic of experimental apparatus for measuring interfacial thermal resistance. Fig.3 Surface morphology of solidified mold flux in contact with the mold. Fig.4 Influence of the height of large cells of solidified mold flux on interfacial thermal resistance for 6 kinds of mold flux.

Fig.3 Surface morphology of solidified mold flux in contact with the mold. Fig.

3 ,2 Fig.4 36mm 5 10cm 2 W/K 2.2 Fig.5 [4] 800K 4.6 ± m 2 /s 1073K 1000K 800K Fe 2.6% Fig.6 Cuspidine(Ca 4 Si 2 O 7 F 2 ) Carnegieite(NaAlSiO 4 ) Fig.5 Measured thermal diffusivity of crystalline and glassy mold fluxes. Fig.6 X-ray diffraction patterns of mold fluxes: (a) crystallized mold flux and (b) rapidly quenched mold fluxes. 2.3 Pulse laser Pulse laser [5] Fig.7 Fig.8(a) T(l 2) t (a) Upper plate Molten sample Lower plate l l 2 T(l 2+ l) t (b) Micrometer Mullite tube Platinum crucible (upper plate) Molten sample Platinum crucible (lower plate) Infrared detector Fig.7 Schematic diagram of differential three layered laser flash method for measuring thermal diffusivity of a molten powder.

$6 X-ray diffraction patterns of mold fluxes: (a) crystallized mold flux and (b) rapidly quenched mold fluxes. 2.3 Pulse laser Pulse laser [5] Fig.7 Fig.$

4 20 12,, 61 Fig.8(b) 8 6 (a) (a) / 10-7 m 2 s (b) TiO 2 0.7% TiO 2 2.6% TiO 2 4.9% TiO 2 7.4% TiO 2 9.6% (b) T.Fe 0.4% T.Fe 1.2% T.Fe 2.6% T / K Fig.8 (a) Thermal diffusivity values of molten continuous fluxes determined by the differential three layered laser flash method. These values include the contribution of radiative component at high temperature. (b)these values were obtained by precisely excluding the contribution of radiative component at high temperature Susa [6] [5, 7 10] E α S E = α + S (2) Fig.9 Fig.10 T 1 ε 1 T 2 ε 2 d α q r = β ( T1 4 T2 4 ) n 2 σ β = 0.75αd + 1 ε ε 2 1 σ Stephan-Boltzmann (3) (4)

8 (a) Thermal diffusivity values of molten continuous fluxes determined by the differential three layered laser flash method.

5 ,2 Fig.9 Absorption cpefficient of glassy mold fluxes at elevated temperatures compared with those at room temperature. Fig.10 Extinction coefficient of crystalline mold fluxes at elevated temperatures compared with those at room temperature. Fig.11,12 Fig.11 Amount and ratio of heat flux in molten layer of flux film when total flux film thickness is fixed at 1.5mm. Fig.12 Amount and ratio of heat flux in crystalline layer of flux film when total flux film thickness is fixed at 1.5mm. 3.2 [11] ϖ(0 ϖ < 1) ϖ = 0 Fig.13 ϖ

5mm. 3.2 [11] ϖ(0 ϖ < 1) ϖ = 0 Fig.13 ϖ 0.4 0.8

6 20 12,, 63 ϖ % 4 [12] Table 1 Fig.14 Ozawa [9] [14] Table 1 Conditions and physical properties for mold heat flux calculation [13]. Casting Speed(m/min) Position Solidifying steel shell thickness (mm) Interfacial thermal resistance (10 4 m 2 K/W) Thermal conductivity (W/mK) Emissivity Mold surface temperature (K) Solidus temperature of steel (K) Crytallizing temperature of mold flux(k) 2.0(LC2) 1.6(MC2) 30mm below the meniscus 15t 0.5 (t:min) 2.94d cry , for 0.3 d cry 1.0 (LC2) 16.4d cry, for 0.4 d cry 0.9 (MC2) d cry:crystalline layer thickness(mm) 31.1(steel shell) 383(copper mold) 0.8(steel shell) 0.4(copper mold) 0.7(crystalline flux) (low carbon steel) 1749(medium carbon steel) 1316(LC2) 1436(MC2) Fig.13 Calculated total heat flux for the mold flux layer as a function of scattering albedo. Reported heat flux [13] beyond which cracks occur (upper for LC, lower for MC) d FLUX (mm) Fig.14 Heat flux in mold as a function of total mold flux film thickness.

temperature of steel (K) Crytallizing temperature of mold flux(k) 2.0(LC2) 1.6(MC2) 30mm below the meniscus 15t 0.5 (t:min) 2.94d cry + 3.52, for 0.3 d cry 1.0 (LC2) 16.4d cry, for 0.4 d cry 0.

7 , [1] K.C.Mills and A.B.Fox: High Temperature Materials and Processes, 22(2003), [2], :,92(2006), [3] H.Shibata,K.Kondo,M.Suzuki and T.Emi:ISIJ Int.,36(1996),S179-S182. [4],,,,, :, 82(1996), [5],,,,, :,80(1994), [6] M.Susa,K.Nagata and K.C.Mills:Ironmaking and Steelmaking, 20(1990), [7] M.Susa,K.C.Mills,M.J.Richardson,R.Taylor and D.Stewart:Ironmaking and Steelmaking, 21(1994), [8] J-W.Cho,H.Shibata,T.Emi and M.Suzuki:ISIJ Int., 38(1998), [9] S.Ozawa,M.Susa,T.Goto,R. (Kojima)Endo and K.C.Mills: ISIJ Int., 46(2006), [10] J.Diao,B.Xie,N.Wang,S.He,Y.Li and F.QI: ISIJ Int., 47(2007), [11],,, :,61(1997), [12] J-W.Cho,T.Emi,H.Shibata and M.Suzuki:ISIJ Int., 38(1998), [13],,,,, :,83(1997), [14] H.Nakada,M.Susa,Y.Seko,M.Hayashi and K.Nagata: ISIJ Int., 48(2008),

Stewart:Ironmaking and Steelmaking, 21(1994), 279-286. [8] J-W.Cho,H.Shibata,T.Emi and M.Suzuki:ISIJ Int., 38(1998), 268-275. [9] S.Ozawa,M.Susa,T.Goto,R. (Kojima)Endo and K.C.Mills: ISIJ Int.

J. Jpn. Inst. Light Met. 65(6): 224-228 (2015)

J. Jpn. Inst. Light Met. 65(6): 224-228 (2015) 65 62015 224 228 ** Journal of The Japan Institute of Light Metals, Vol. 65, No. 6 (2015), 224 228 2015 The Japan Institute of Light Metals Investigation of heat flow behavior on die-casting core pin with