Disordering induced work softening of Fe-6.5 wt%Si alloy during warm deformation

The application of Fe-Si electrical steel as iron cores of transformers and engines requires it to be cold rolled into thin sheet because the deformation process is a path directly reaching a final dimension with good magnetic and mechanical properties. However, it is impossible for the Fe-6.5 wt%Si alloy to be directly cold rolled due to its embrittlement. One alternative way to improve its workability is warm rolling. In this work, warm deformation behavior of Fe-6.5 wt%Si alloy is studied. The results show that the flow stress decreases remarkably after 30% compression, accompanying with a reduction of micro-hardness, indicating a work softening behavior of the alloy. The size of the ordered domains and the degree of order decrease gradually with deformation, and a disordered alloy is obtained finally. When deformation reaches a certain value, small dislocation cells appear and finally subgrains are formed indicating the occurrence of dynamic recovery. It is concluded that the deformation-induced disordering and dynamic recovery are the main softening mechanisms. (C) 2015 Elsevier B.V. All rights reserved.