Modelagem e análise numéricas da operação de roleteamento do aço ABNT 4140

Abstract

Metallic components used in engineering applications are seldomsubjected to the action of thermal and mechanical loads, which tend to reduce their lifespan. Mechanical surface treatments appear as an alternative capable of extending the service life of these materials. These processes act by plastically deforming the surface, reducing its roughness, increasing its hardness and inducing compressive residual stresses. The combination of these factors leads to an increase of material lifespan because it diminishes the nucleation and propagation of cracks, whichare responsible for material failure by fracture. Although the induction of compressive residual stress is one of the most effective factors increasing part life, the final roughness of the component plays an important role. Thus, although surface treatment processes such as shot peening and laser shock peening are used to induce compressive stresses, deep rolling not only induces compressive stress and increases surface hardness, but also promote the reduction of surface roughness. In this work, two-dimensional numerical simulation using the Finite Element Modelling (FEM) method was applied to deep rolling of hardened AISI 4140 steel (40 HRC), considering the tool a rigid element, while the part was assumed as elasto-plastic. Rolling force and feed rate were selected as input parameters which influence roughness, effective deformation, residual stress induction and effective stresses on the workpiece. Moreover, unlike other two-dimensional numerical models, the initial roughness of the part was introduced in order to verify its influence on the process. The HertzWin software was used to define the feed rate for each condition, which was based on the half contact width (b) obtained for each force separately. The analysis of the simulation results suggests the reduction of roughness, as well as the increase of effective deformation,compressive residual stress and effective stress when the rolling force is increased and the feed is reduced. The results were consistent with the literature.