Effect of sliding velocity on friction-induced microstructural evolution in Copper

Durability of engineering workpieces surfaces is well-known to be strongly related to the microstructural evolutions induced by machining processes. One current challenge is to choose the right process parameters, such as the sliding speed, in order to optimize both the subsurface microstructure and the surface properties. In this paper, a special tribometer, able to simulate contact pressures and cutting speeds occurring during machining, has been used to characterize the effect of sliding velocity on microstructural evolution induced in copper. Significant recrystallization and grain refinement phenomena have been observed for the highest sliding speed tested (250m/min). Finite element analysis have been performed to extract local variables near the pin/copper bar interface. A good agreement is noticed between the equivalent plastic strain level, the temperature rise, the resulting grain size and the hardness gradient.