电脉冲对亚共晶铁碳合金共析组织的影响

Influence of electric current pulse treatment on eutectoid structure of hypoeutectic Fe-C alloy

研究了不同输出电压下的电脉冲(ECP)处理对亚共晶铁碳合金共析组织的影响。结果表明,施加电脉冲处理产生焦耳热效应,增加了组织中原子的扩散能力和奥氏体长大的驱动力,促进了奥氏体的长大,加速了渗碳体的分解。电脉冲处理所产生的电子风力,使运动位错数量的增加。位错运动导致的位错塞积,致使渗碳体分解。渗碳体分解使奥氏体中产生浓度起伏,再加上电脉冲处理使相变势垒降低、石墨生成所需的相变驱动力减小,最终导致亚共晶铁碳合金组织中低温莱氏体的数量减少,促进石墨的生成。石墨的生成增加了铁素体的形核率和长大速率,使铁素体含量增加,珠光体含量减少。随着电脉冲输出电压的升高,ECP处理效果越加明显。

The eutectoid structure of hypoeutectic Fe-C alloy by applying electric current pulse( ECP) with different output voltages was analyzed. 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 accelerates cementite decomposition. In view of the influence of electron wind force made by ECP,it can increase the quantity of moving dislocation. The dislocation pile-up which made by the dislocation motion leads to cementite decomposition. Cementite decomposition 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 a result,the amount of ledeburite in hypoeutectic Fe-C alloy decreases and graphite increases. Furthermore,it also increases the nucleation rate and growth rate of ferrite,which makes the relative amount of ferrite increase and the relative amount of pearlite decrease. According to present experiments,the effect becomes more obvious with the increasing output voltage.