Influence Of Original Microstructure On Rolling Wear Performance Of D2 Wheel Steel

Nowadays,domestic railway transportation develops prosperously,train wheels are directly related to the safety of the train operation and the property of passengers,therefore,it is necessary to study the microstructure evolution and the wear properties of the wheel.In this experiment,GPM-30 friction wear testing machine was used to conduct rolling wear tests on different D2 wheel steels whose original microstructures are lamellar pearlite+proeutectoid ferrite and tempered sorbite.SEM and other devices were used to detect the specimens after tests.The difference in wear properties of the two kinds of specimens and the reasons to this phenomenon were analyzed.The results showed:The polygonization will accelerate the wear phenomena of the specimens.The specimens whose original microstructure is tempered sorbite are more likely to form polygonization on their surface and the mass loss and wear rate of them the are also higher than those specimens with lamellar pearlite and proeutectoid ferrite as the original microstructure.The macroscopic wear morphology,mass loss and wear rate of the two kinds of partner specimens matched with the two kinds of major specimens were approximately the same.After 2×105 revolutions,the surface wear mechanisms of the two kinds of specimens were both dominated by adhesive wear and oxidative wear and the surface roughness of the specimens with tempered sorbite was higher.Thus,the coefficient of friction of them increased more obvious.The deformation degree of the plastic deformation layer of the two specimens decreases with the increasing of depth to the surface.The deformation degree of the plastic deformation layer of the specimens with lamellar pearlite+proeutectoid ferrite is higher.Within the range of 10?25?m from the surface,the deformation degree of proeutectoid ferrite in specimens with lamellar pearlite+proeutectoid ferrite is lower than that of the isoaxial ferrite at the same depth in specimens with tempered sorbite.When the distance from the surface is less than 10?m,the deformation degree of the former is higher than that of the latter.Therefore,there is a stronger hardening effect formed within the surface area of the former specimens,resulting in the better wear resistance of their surface.The highest hardness appears on the topmost surface for both specimens.The hardness of specimens with tempered sorbite increases by 78%and the valid hardening layer thickness is about 20?m.Higher degree of hardening effects happen on the specimens with lamellar pearlite+proeutectoid ferrite,witch can reach up to 95%.The valid hardening layer for the latter is thicker,about 125?m thick.Thus,the latter have a stronger hardening ability.During the process of rolling,only single strengthening effect caused by ferrite was dominant in the specimens with tempered sorbite.While for specimens with lamellar pearlite+proeutectoid ferrite,strengthening effects caused by ferrite and cementite and proeutectoid ferrite happened on the rolling surface.Above all,under the condition of dry friction rolling wear,the specimens whose original microstructure is composed of lamellar pearlite+proeutectoid ferrite have more prominent hardening effect than that of the specimens with tempered sorbite.The former have the better resistance to polygonization and the better wear resistance.