Influence of the Electric Current Pulse with Different Pulse Width on the Eutectoid Microstructure of Hypoeutectic Fe-C Alloys

Abstract

The influence of the eutectoid structure of hypoeutectic Fe-C alloys by applying electric current pulse (ECP) is carried out. The experiment results show that ECP treatment can produce Joule heating. Joule heating increases the diffusion capability of atoms and the driving force of austenite growth, which promotes austenite crystal growth and accelerate cementite dissolution. In view of the influence of the electron-wind-force made by ECP, it can increase the quantity of moving dislocation. The dislocation pile-up which made by the dislocation motion lead to cementite dissolution. Cementite dissolution can lead to concentration fluctuation in Austenite. ECP can also make the phase transformation barrier and the phase transition drive force of graphite formation decrease. As the result, these phenomena can make cryogenic ledeburite become less and graphite increase. Furthermore, it can also increase the nucleation rate and growth rate of ferrite, which can make the relative amount of ferrite increase and the relative amount of pearlite decrease. Based on our experiments, the effect becomes more obvious with the pulse width increase.