Effect of yttrium addition on the hot deformation behavior of Fe–6.5 wt%Si alloy

Abstract

Due to its remarkable soft magnetic properties, the Fe–6.5 wt%Si alloy has shown potential in energy-saving and noise-reducing applications. However, the appearance of brittle-ordered structures hinders its production and utilization. It has been previously indicated that rare earth (RE) elements can be used as inclusion modificators as well as for purification of molten steel and microalloying. In the present work, the effects of yttrium (Y) on the hot deformation of the Fe–6.5 wt%Si alloy was studied by hot compression at temperatures of 600–900 °C at different strain rates. Moreover, the processing maps were established according to the dynamic materials models (DMM), which determined the range of optimal process conditions. The obtained results demonstrated that in the range of 600–900 °C, the activation energy for hot deformation of the Fe–6.5 wt%Si alloy was 428.68 kJ/mol, which is lower than that of the alloy containing 0.03 wt%Y (473.27 kJ/mol). It is speculated that Y decreases the unstable region and apparently reduces the occurrence of microcracks during the hot deformation process of the Fe–6.5 wt%Si alloy. In addition, the presence of this element leads to an increase in the dislocation density and causes segmentation of the ordered domain. Lastly, the addition of Y improves the ductility of the Fe–6.5 wt%Si alloy due to grain refinement and reduction of the ordered domain size.