Influence of Vanadium Microalloying on Isothermal Transformation Behavior of Eutectoid Steel

Resumo

Abstract—The influence of vanadium as a microalloying element on the austenite decomposition behaviors and microstructure transformation of eutectoid steel were studied during isothermal cooling. Vanadium dissolved in γ matrix exhibited a negative effect on austenite decomposition to pearlite microstructure and led to a decrease in the lamellar spacing. Moreover, the results indicated that the dissolved vanadium segregated toward austenite grain boundaries and suppressed the formation of grain boundary ferrite. However, the precipitation of vanadium during the isothermal process led to a decrease in vanadium dissolved in matrix that indirectly promoted transformation to pearlite. The precipitates could act as nucleus for pearlite formation, which also accelerated the transformation. The lamellar spacing of pearlite increased as a result of carbon consumption of precipitates. The addition of nitrogen remarkably accelerated the transformation, because the chemical driving force for VN formation was significantly larger.