Alternation on rolling contact properties of steel due to magnetic field

This paper describes the effects of magnetic field on rolling contact performance of steel/steel disc couple and presents an investigation into the mechanisms governing these effects by applying contact mechanics and magnetism theory. The tests were carried out in disc-on-disc contact configuration under 1.1 T [Tesla] of horizontal static magnetic fields created by permanent magnets in three different orientations. Wear amounts were decreased in the magnetic fields and there was difference in magnetic field orientation. For the characteristic of the surface, results of scanning electron microscope observations point out that finer wear particles and smoother worn surfaces are produced in the presence of magnetic field. The smoother surfaces are also confirmed by surface roughness measurements. For the generation of the finer wear particles, it is considered that subsurface crack initiation point is moved toward the surface due to magnetic field. The effect of magnetic field is considered by calculating the number of cycles required to generate wear particles and the cycle was reduced due to the presence of magnetic field. It is considered, from views of contact mechanics and magnetism theory, that domain walls near the contact region are caught by dislocations when the specimen is magnetised and part of the energy for magnetisation activates the dislocation movement resulting in crack initiation. (C) 2009 Elsevier B.V. All rights reserved.