Molecular Dynamics Investigations for Surface Mechanical Attrition Treatment

Author:  A. Rida, E. Rouhaud, M. Micoulaut, A. Makke, D. Retraint
Source:  ICSP-13
Doc ID:  2017091
Year of Publication:  2017
Abstract:  
Introduction: In surface mechanical attrition treatments (SMAT) such like shot peening, the surface of a polycrystalline metal is submitted to strong impacts of many hard particles (called shots). Such impacts induce a severe local plastic deformation. This deformation leads to a drastic changes in the polycrystalline structure of the material layer close to the surface. (i) High residual compression stress is generated in this layer. (ii) The high local plastic deformation leads also to an increase in the dislocation and/or twin density. (iii) The grain size deceases and it may reaches the nanoscale. These modifications improve the fracture toughness and fatigue strength of the metal which increases the material lifetime. However, the mechanical behavior of nanocrystalline metal layer is still not well understood. An important issue is therefore to characterize the mechanical behavior of a nanocrystalline metal in and also to understand the crystal refinement during the treatment and its role on the fatigue strength of the material.