Analysis of 3D Morphology and Scratch Hardness of Copper under Large Constant Load

Scratch tests were conducted on copper with a conical indenter. 3D morphologies of the scratches were obtained by a 3D Surface Profilometer, and the influence of normal force on the scratch groove was studied. The results show that width and depth of the scratches increase linearly with the increase in the applied normal force. When the normal force is high, the periodic fluctuation of scratch depth appears due to the formation of the dislocation walls. At the same time, the scratching process is accompanied by pile-up on both sides and in front of the indenter. It is found that height and thickness of the pile-up at the end of the scratch and the height and width of the pile-up on both sides of the scratch increase linearly with the increase of the applied normal load. The ratio of cutting to plasticity shows two deformation mechanisms: micro-ploughing and micro-cutting, and micro cutting mechanism plays the dominant role in the scratching process, resulting in a linear increase of wear rate with the increase of normal load. The scratch hardness does not change with the variation of normal load, and can be regarded to be a constant about 0.77 GPa.