Impact and Sliding Wear Resistance of Hadfield and Rail Steel
Résumé
Railway networks are subjected to more and more severe loading conditions requiring the use of steels with a high resistance to wear and good fatigue behaviour. The surveys carried out on out of use equipment, such as rails or switches, show that these equipments fail by wear after quite a long period of use, but they can fail by fatigue in a substantially shorter time. In service, crossings are submitted to rolling, impact and sliding stresses. The impact-sliding is the result of the wheel transition from rail wing to crossing nose. Very high contact forces act on the crossing nose while such wheels are passing over it. These large contact forces between wheel and crossing can cause severe damage at crossing nose and wing rail. The influence of contact parameters on the damage of the crossing alloy (Hadfield steel GX120Mn13) in comparison with rail steel (R260) was investigated by impact and impact-sliding tests. The results are described and discussed using weight loss and microhardness measurements, optical and scanning electron microscopy observations of the contact surface. Examination of the results shows large plastic deformation in surface and subsurface of samples. In comparison with impact tests, sliding produces a change in size and shape of the contact area, a higher weight loss and lower hardening. A better impact-sliding wear resistance of Hadfield steel has been confirmed.