Study On Friction And Wear Characteristics Of Alloy CF170 Steel

CF170 steel is a new developed alloy steel to replace 2Cr13 steel.Due to its good mechanical properties and processing properties,It has become an important material for the manufacture of gears,transmission shafts and other structural components and structural parts in spacecraft,showing promising application.If the gears are prepared with CF170 steel,the analyzation of the friction and wear behavior are carried out and providing useful information technology parameters for engineering applications.In this paper,CF170 steel is used as the evaluation object.The GCr18 steel ball is selected as the friction pair.The experimental study of dry sliding friction and wear was carried out with the MFT-5000 multi-function friction and wear test machine under ball-disc friction wear mode.The test conditions is that the loding of 5N,7N,9N 11 N,13N and rotation speed of 0.167m/s,0.251m/s,0.335m/s,0.418m/s and sliding time of 1800 s.The morphological characteristics of the wear scars of the disc samples were analyzed by SEM,and the semi-quantitative analysis of the element distribution and content was carried out by using EDS.The relevant data of friction force,friction coefficient and load,speed and wear distance were obtained with the data acquisition system of the friction and wear testing machine,and corresponding analysis and discussion were carried out.The experimental results show that the friction force increases synchronously with the increase of load and speed.The change of friction coefficient is affected by load and speed.When the load is constant,the friction coefficient increases with the increase of speed.When the speed is constant,the friction coefficient decreases as the load increases.The trend of wear quality change is basically consistent with the change of friction force with the increase of load and speed.Through the analysis of the wear scar morphology of SEM,it is found that when the load is constant,the furrow of the wear scar becomes wider and wider with the increase of the load.When the rotation speed is constant,the surface of the wear scar gradually from a clear visible furrow to the chaotic features.The shape of the wear debris is characterized by a variety of fine,finely distributed,granular abrasives,as well as flaky wear debris and adhesive wear debris.It can be seen that the friction and wear mechanism is the result of the coexistence of particle wear and fatigue spalling wear and adhesive wear.Through observation and analysis of the cross-section of the wear scar,it can be seen that under different conditions,the cross-section of the wear-receiving furrow is distributed with cracks of different degrees near the furrow,which is a typical fatigue wear characteristic.It shows that fatigue wear and particle wear are the main wear mechanisms.The energy spectrum(EDS)analysis of a specific area of the worn surface under different load conditions at 0.167m/s found Oxygen and Cobalt element,except for the unworn disc samples.As the load increases,the content of oxygen increases.This reflects the existence of oxide film formed by oxidation,which indirectly explains the reason why the friction coefficient decreases with increasing load.