摘要
Abstract
During the high-speed operation of the rocket sled,the friction pair composed of the slipper and the track continuously experiences friction.Due to the lack of effective lubrication measures between the slipper and track,the surface of slipper is severely worn.In order to make the sled pass smoothly on the track,there is usually a certain gap left between the slipper and the track.As the surface of the slipper wears down,the gap between the slipper and the track continues to increase,changing the operating state of the sled.When the slipper is severely worn,it can even disrupt the operation stability of the sled and pose a threat to test safety.In order to control the wear of the slipper,it is necessary to understand the wear behavior of the slipper during the track operation of the rocket sled.The work aims to conduct a single track rocket sled test with consistent operating conditions based on U71Mn steel rails and bainitic steel rails.In the test,the maximum speed is 900 m/s,and the sled slides 6.4 km along the track.After the experiment,the sled will be recycled and the 30CrMnSiNi2A front sliding shoes will be taken as the research object.Two front slippers are analyzed separately and the friction and wear characteristics of 30CrMnSiNi2A slipper-U71Mn rail friction pair and 30CrMnSiNi2A slipper-bainitic rail friction pair are studied.The three-dimensional morphology and two-dimensional contour features of the worn surface of the slipper are analyzed with confocal microscopy.The microstructure and elemental distribution of the worn surface of the slipper are investigated through scanning electron microscopy and energy dispersive spectroscopy.The phase composition of slipper materials subject to friction and wear is explored with an X-ray diffraction analyzer.The cross-sectional hardness and microstructure of the sliding shoe are analyzed with a Vickers hardness tester and scanning electron microscope.The wear mechanism of 30CrMnSiNiA slipper,whether running on U71Mn rail or bainitic rail,is mainly abrasive wear,accompanied by slight adhesive wear,fatigue wear,and oxidative wear.After running on U71Mn and bainite rails,the local hardness of the worn surface of the 30CrMnSiNiA slipper increases.The highest hardness of the worn surface of the slipper paired with U71Mn rail is 720HV,and the highest hardness of the worn surface of the slipper paired with bainite rail is 795HV.However,as the depth increases,the hardness gradually decreases to the hardness level of the substrate material.Grain refinement is the main reason for the increase in the hardness of the slipper,which is related to material work hardening caused by high friction heat and high normal load.The 30CrMnSiNiA slipper running on the U71Mn rail has a larger wear surface roughness,more peeling pits,and deeper wear marks compared to the 30CrMnSiNiA slipper running on the bainitic rail.It also exhibits thicker deformation layers and more pores rich in oxygen,silicon,and other elements on its wear cross-section.This means that the 30CrMnSiNiA slipper has better wear performance when running on the bainitic rail.The 30CrMnSiNi2A slipper has better wear resistance performance when running on the bainitic rail.Therefore,sled rockets with30CrMnSiNi2A slippers should be tested on bainitic rails first.关键词
30CrMnSiNi2A钢/滑靴/U71Mn轨道/贝氏体轨道/表面形貌/磨损机理Key words
30CrMnSiNi2A steel/slipper/U71Mn rail/bainitic rail/surface morphology/wear mechanism分类
机械制造
