A wear model based on cumulative cyclic plastic straining

Issu de : WOM 09 - 17th International Conference on Wear of Materials 19-23 April 2009 • Las Vegas, USA; International audience; Given the specific micro‐structure of some steel grades, under tribological conditions the sub‐surface material or sub‐layers of sliding bodies are prone to cumulative cyclic plastic deformation, leading to the formation and emission of wear debris. In the present paper, a new wear model based on a cyclic ratchetting‐type plastic deformation of subsurface material is proposed. It is considered that the debris is formed and the wear‐loss occurs when the accumulated plastic deformation at sub‐surface exceeds ``a critical strain'' or ``rupture limit''. The model takes into account the number of cycles or test duration, a characteristic thickness of the sub‐layer dependent on tribological conditions and material properties, the shear rupture ductility and an average plastic strain increment. The average plastic strain increment is estimated by numerical simulation of pin‐on‐disc friction. A very close correlation is found between the predicted and experimental wear heights versus time and/or versus the number of cycles. The wear investigations were carried out on a high‐temperature pin‐on‐disc tribometer under dry friction conditions. Experiments were performed under constant load, speed and disc temperature for different durations. The steel grade involved was a tempered martensitic tool steel X38CrMoV5 (AISI H11). Wear mechanisms were investigated by Scanning Electron Microscopy (SEM) observations in surface and cross‐section.