Effect of pulsed magnetic field on network carbides in GCr15 bearing steel
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(Rm)and yield strength(Rp0.2)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).
GCr15 bearing steelpulsed magnetic fieldnetwork carbide
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