Development of a novel high temperature open tribometer with laser-based heating system

Abstract

Contacts operating under severe conditions such as high temperatures, contact pressures and/or sliding velocities, can occur in many applications and especially in metalworking processes. The extreme thermomechanical loadings withstood by the tooling during such interaction directly govern their lifetime but also the functional properties of the component surface. Understanding the friction and wear mechanisms behind is still an issue and can only be addressed with a relevant experimental set-up. This work presents the development of a new laser-based heating system fitted on an open tribometer with the aim of investigating such severe contact conditions for a AISI1045 carbon steel during sliding against uncoated cemented carbide. A 3D numerical approach is adopted to design the system and predict the temperature distribution, as well as the heating rates, below the laser beam and at the expected contact zone. A phase transformation model based on the simulated thermal kinetics is applied to identify the conditions leading to the potential formation of austenite and to show that a proper combination of laser power and sliding velocity has to be selected to ensure the desired contact conditions. It is shown for example that even at high sliding velocities, a maximum temperature of 600∘C can be reached in the contact zone without exceeding the melting temperature ahead while only a thin layer can be affected by the laser. The experimental set-up is described with the integration of a laser head into the test bench. An experimental campaign is carried out to show the influence of the temperature and sliding conditions on the tribological behavior especially in terms of friction, wear mechanisms and microstructural evolution beneath the contact track.