Effect of grain size and grain boundary on ductile to brittle transition behavior of Fe-6.5wt.%Si alloy under miniaturized three-point bending tests

Abstract

This research investigates the influence of grain size and grain boundary on the ductile to brittle transition (DBT) behavior using three-point bending tests. With increasing grain size from 91 μm to 255 μm, the ductile to brittle transition temperature (DBTT) increases by approximately 80 °C, accompanied by a corresponding 0.196 eV increase in DBT activation energy. An evident linear reciprocal relationship exists between DBTT and grain boundary ratio. The Hall-Petch equation is employed to determine the quantitative relationship between the DBTT and grain size, offering novel guidance for determining the rolling temperature of Fe-6.5wt.%Si alloy.