45号钢在往复冲击载荷作用下的塑性变形

摘要：采用钢球冲击45号钢盘，观测了在不同接触条件、冲击次数及载荷条件下钢盘表面的塑性变形情况．发现在低冲击次数条件下，使用低黏度油的凹坑深度与干接触相近，但在高次数冲击条件下，冲击深度与干接触条件下相比大幅度变浅．而高黏度油条件下的凹坑深度一直最浅．在其他条件相同时，冲击深度随载荷的增加而增加．冲击时，由于凹坑中心产生的热量不断向边缘传递，使凹坑边缘形成凸起即形成所谓彩虹环．彩虹环随润滑油黏度的增加及载荷的增加而高度增加．润滑油的使用可以降低材料表面的塑性变形和磨损．对于干接触条件，凹坑内部发生微细颗粒碎化．而油润滑时凹坑内部出现微裂纹．微细颗粒碎化及微裂纹的程度均随冲击次数和载荷的增加而增加．

Plastic deformation of steel no. 45 under reciprocating impact load

In the experiment,we use a steel ball to impact the plate of no.45 steel.The plastic deformation of the dent is observed under different contact conditions,impacting times and loads.Through the observation,we found that at low impact times,the depth of the dent by using the low viscosity oil is close to that while impacting under dry contact condition,but at high impact times,the depth of the dent by using the low viscosity oil is obviously shallower than that while impacting under dry contact condition.And the depth of the dent by using the high viscosity oil is always the shallowest.When the other conditions are the same,the depth of the dent increases with the loads.While impacting,the heat produced from the center of the dent transmits to the edge continuously,which causes the edge of the dent form the convex,we call it the iridescent ring.The height of the iridescent ring increases with the increase of the viscosity of the oil and the load.The use of the lubricating oil can reduce the plastic deformation and the wear of the materials.Under the dry contact condition,superfine particles are found inside the dent.Microcracks occur inside the lubricated dent.The fragmentation of the superfine particles and the degree of the microcracks increase with the impacting times and loads.