Effects of work hardening on mechanical metal properties—experimental analysis and simulation by experiments

Abstract

The aim of the present work is to improve the materials’ performances, particularly their elastic property based on an optimal exploitation of surface work-hardening phenomenon, using surface plastic deformation treatment (DPS). The surface of a mechanical piece is considered as the most vulnerable zone that determines its mechanical performances. To improve the surface physico-mechanical properties, the surface plastic deformation treatment (DPS) is often used. The (DPS) acts by a combined action of: surface hardening, structural modification, and the generation of the compression residual stresses, the factors that will create a heterogeneous plastic deformation. Knowing that during operation the mechanical pieces have to be subjected to a stress smaller than the elastic limit (taking into account the safety margins), where the material behavior is reversible, and to reach the maximum allowable stresses, we have to increase the material’s elastic limits. This objective can be realized through an optimal use of work hardening phenomenon for the treated surface by the DPS. The work hardening is characterized by the increase of the yield strength (Re), the surface hardness (Hv), and consequently the increase of the brittleness. Depending on the considered metals, when the piece has a defect variation: cavity, inclusion (precipitate), or zones of different hardness, it can create a stress concentration which generates a local hardening. This phenomenon is one of the main causes of crack generation. In our study, we consider the influence of work hardening on the elastic behavior of XC38 steel and aluminum alloy.