Effect of Si addition on the damping capacity of a high carbon steel

The aim of this study is to investigate the effects of Si addition and annealing process on the microstructure and damping capacity of Fe-1.1wt.%C and Fe-1.1wt.%C-2.0wt.%Si steels. The damping capacity increases with increasing annealing time, and for the same annealing time, the damping capacity is larger in Fe-1.1wt.%C-2.0wt.%Si steel than Fe-1.1wt.%C steel. It is revealed that the damping capacity consists of three parts: the damping capacity due to the migration of magnetic domain boundaries in matrix (Δδm), the damping associated with the precipitated graphites (Δδgr) and the background damping of the material (δ0). The contributions of Δδm and Δδgr to the total damping capacity of the steels increase with increasing annealing time. The Δδgr is linearly dependent on the volume fraction of graphite to the 2/3 power, f2/3, which corresponds to the total surface area of graphites. This indicates that the plastic flow across the interphase boundaries between matrix and graphites is a damping mechanism of Δδgr.