Microstructure of unidirectionally solidified Fe-V-C alloy and interface temperature measurement of γ+VC eutectic carbide

摘要

Alloying elements such as Cr, W, V, Mo of the high speed cast iron for hot rolling have been added to improve fracture toughness and wearing resistance. It is important to control solidification structures of these cast irons including eutecticcarbides, M{sub}3C, M{sub}7C{sub}3, M{sub}6C and MC. Therefore, it is required to predict which carbide will solidify at certain composition and solidification condition. This prediction criteria will be gained by measuring the interface temperature ofeach carbide in various samples with different solute elements, composition and growth rate. In this report, the solidification temperature ofγ+VC eutectic in Fe-V-C ternary system was measured during the directional solidification process. Therelationship between solidification temperature and growth rate was obtained. In eutectic solidification alongγ+VC mono-variant lines, coefficient of under-cooling, according to equation△T = k square root of V was obtained. At 1μm/sec growth rate,γ+VC/γ+M{sub}3C banded structure was observed. The paper also discussed aboutγ+VC/γ+M{sub}3C banded structure formation at low grow4h rate, where the conditions under which theγ+VC+M{sub}3C ternary eutectic was expected to solidify.