脉冲磁场对GCr15轴承钢网状碳化物的影响

Effect of pulsed magnetic field on network carbides in GCr15 bearing steel

在GCr15轴承钢的球化退火过程中施加脉冲磁场,研究脉冲磁场对其组织形貌和力学性能的影响,探讨脉冲磁场作用下网状碳化物溶解的热力学和动力学机理。结果表明:随着施加脉冲磁场时间的延长,GCr15轴承钢中沿晶界分布的碳化物由封闭网转变为半网,当施加脉冲磁场时间为20 min,晶界处的网状碳化物消失。这主要是由于施加脉冲磁场后,在热力学方面网状碳化物溶解的势垒降低,动力学方面原子扩散系数增大,这都促进了网状碳化物的溶解。随着施加脉冲磁场时间的延长,GCr15轴承钢的抗拉强度(R_(m))和屈服强度(R_(p0.2))基本保持不变,伸长率(A)提高了18%(从5 min的33%提高到20 min的39%),断面收缩率(Z)提高了13%(从5 min的61%提高到20 min的69%)。

During the spheroidization annealing process of GCr15 bearing steel,a pulsed magnetic field was applied,the effect of the pulsed magnetic field on its microstructure and mechanical properties was investigated,and the thermodynamic and kinetic mechanisms of the dissolution of network carbides under the action of the pulsed magnetic field were analyzed.The results show that as the time of applying the pulsed magnetic field increases,the carbides distributed along the grain boundaries in the GCr15 bearing steel change from a closed network to a semi-network.When the pulsed magnetic field is applied for 20 min,the network carbides at the grain boundaries disappear.This is mainly because that the application of a pulsed magnetic field reduces the energy barrier for the dissolution of network carbides in thermodynamics and increases the atomic diffusion coefficient in kinetics,both of which promote the dissolution of network carbides.As the applying time of the pulsed magnetic field increases,the tensile strength(R_(m))and yield strength(R_(p0.2))of the GCr15 bearing steel remain basically unchanged,the elongation(A)increases by 18%(from 33% for 5 min to 39% for 20 min),and the reduction of area(Z)increases by 13%(from 61%for 5 min to 69% for 20 min).