油润滑下钢严重磨损表面的分形特征

本文在ＭＨＫ－５００型环－块试验机上于２０号内燃机油润滑下对４５＾＃钢（炉冷）、４５＾＃（水淬）、ＧＣｒ１５钢和Ｗ１８Ｃｒ４Ｖ钢进行了滑动磨损试验，得到了表征这４种钢试样由轻微磨损向严重磨损转变的Ｐ（临界载荷）－Ｖ（临界滑动速度）曲线。对严重磨损表面进行扫描电子显微镜观测的结果表明，在一定的标度范围内其表现裂纹具有分裂特征。在给定的试验条件下，利用Ｓａｎｄｂｏｘ法测量出上述４种钢严重磨损表面裂纹的

Fractal Character of Severe Worn Surfaces for Four Different Steels under Oil Lubrication

The sliding wear tests for four different steels were carried out on a Model MHK-500 ring-block wear testing machine under 20# engine oil lubrication. The curves of P * (the critical load)- V * (the critical sliding speed) were obtained at transition point from mild wear to severe wear. The severe worn surfaces were observed by scanning electron microscope (SEM). The results indicated that the surface cracks have fractal character in a certain scale range. Using Sandbox method, the fractal dimension value ( D'f ) of these surface cracks was measured and found that the range of D'f is between 1. 65 to 1. 76. The curves of P * -V * are representative of anti-scratching ability of the four different steels and the transition point of steel from mild wear to severe wear can be judged by the fractal dimension value.