Enhancement of fatigue performance of 20Cr2Ni4A gear steel treated by pulsed magnetic treatment: Influence mechanism of residual stress

Abstract In order to study the influence of pulsed magnetic field on the fatigue properties of 20Cr2Ni4A steel, pulsed magnetic treatment and rolling contact fatigue experiments are carried out on 20Cr2Ni4A steel samples. The mechanical properties and microstructure of the materials are investigated by X-ray diffraction and transmission electron microscopy (TEM). Combined with COMSOL simulation, the influence mechanism of pulsed magnetic treatment is explored. The experimental results show that the contact fatigue property of 20Cr2Ni4A steel is improved by pulsed magnetic treatment, which is related to the effect of pulsed magnetic treatment on the residual stress. The mechanism of magnetic field action includes promoting the increase of dislocation movement, and the accumulated dislocation starts to disperse, reducing stress concentration. Magnetostriction caused by magnetic domain rotation increases the residual compressive stress near the surface. The increased residual stress can offset a certain external load and reduce the actual force of the parts, thus prolongs the contact fatigue life.