Improvement in uniformity of alloy steel by pulsed magnetic field treatment

Abstract

This article reports that the uniformity of the alloy steel 20Cr2Ni4A is improved by using pulsed magnetic treatment. The pulsed magnetic field with 1, 4 and 9T was applied on the tempered samples. Meanwhile the microstructures were characterized using transmission electron microscopy and magnetic force microscopy, and mechanical properties tested to verify the effect of the proposed process. It shows the contact fatigue life of alloy steel increases by 42.11% after magnetic treatment. Range of residual stresses narrows down along with rise of magnetic induction strength. The microstructures of dislocations, precipitates, and magnetic domains become more uniform under pulsed magnetic field. Besides, dislocations and precipitates were observed to transit from intergranular agglomeration to intracrystalline distribution. The energy of the external magnetic field promotes the dislocation slip and reduces high dislocation density on grain boundaries, which results in a decrease of residual stress.