| Because of its low cost and excellent performance,steel is still one of the most widely used metal materials.In actual working conditions,the service process of equipment and components is not only subjected to a single wear load,but also generally subjected to fatigue load.In the wear load or wear and fatigue load under the joint action of components,many times will occur early failure fracture.There are few researches on the dry friction and wear behavior of steel materials.In this paper,20Cr Ni2Mo low carbon steel is taken as the research object to study its dry friction and wear characteristics and wear bending fatigue life.By means of laser confocal microscope,scanning electron microscope,transmission electron microscope and other technical means,the influence of oxidation on dry friction and wear of ball disc is revealed,and the factors affecting wear bending fatigue life are preliminarily given.These studies provide theoretical guidance and reference for the study of dry friction wear and wear bending behavior of steel materials.(1)20Cr Ni2Mo steel was subjected to dry friction and wear test.By changing the positive pressure,rotation speed and friction time,the friction coefficient curve of the double platform was obtained.The normal pressure is 100 N and the linear velocity is50 r/min.After 300 s of dry friction and wear,the friction coefficient drops to 0.25 soon.The process of friction coefficient decreasing is closely related to the oxidation of surface wear chips.Through comparison,it is found that if the dust particles formed on the surface are removed,the phenomenon of rapid decrease of friction coefficient will not occur.Dry friction and wear process of friction specimens under the action of shear stress,surface grinding chip,chip under the effect of surface after heat and mechanical coupling,after oxidation of wear debris on the surface abrasion form a layer of oxidation protection film,found by scanning electron microscopy(sem)and transmission electron microscopy(sem)characterization of oxidation protection film is made up of about 10 nm size and Fe3O4 Fe2O3 nanoparticles,nano oxide particles form protective film,can reduce the surface roughness,friction coefficient and wear rate,improve the effect of wear surface morphology.(2)On the basis of the bending fatigue testing machine,by installing the friction auxiliary device,the machine can be transformed into a wearing bending fatigue prototype that can complete the wearing bending fatigue samples.The wear bending fatigue testing machine can change the wear load by changing the wear auxiliary device.Wear by changing load,the bending stress under the action of fatigue behavior of different high bending stress,when wear load increase to 12 N fatigue life down to 6.15x 10~6quickly,continue to increase the load to 24 N,fatigue life down to 2.71 x 10~6,abrasion wear with the increase of load on bending fatigue life,fatigue life drastically;Wear fatigue life can exceed 10 million times under low bending stress.Under the same stress condition,the wear of 3200 r/min rotation speed is mainly adhesive wear.The size of grinding chips is generally more than 200μm,and deep furrows are formed on the worn surface.At a speed of 1300 r/min,the main reason is oxidation wear.At a low speed,the chip shedding speed and size become smaller,and the chip size is below 10μm. |
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