MODELACIÓN DEL COMPORTAMIENTO DE CAPAS DURAS BAJO CARGAS DE INDENTACIÓN

Abstract

The present study describes the mechanical behavior under indentation loads of the Fe2B layer which is formed on the surface of AISI 1018 steel by the thermochemical treatment of boriding. The nanoindentation technique and the Vickers indentation fracture technique are used to evaluate the residual stresses in the interface layer-substrate and fracture toughness of the Fe2B layer respectively. The numerical simulation of the nanoindentation test by means of finite element method and the developed experimental are the bases to establish a expression which describes important mechanical parameters such as: residual stresses generated for the thermochemical treatment of boriding, which influence directly on the behavior of the mechanical components subject to hardness surface treatment, because of the fact that in function of their magnitude and type (tension or compression) to increase or decrease the wear resistance and abrasion resistance of such mechanical components. On the other hand, the cracking in brittle materials like is the case of hardness layers by boron diffusion Fe2B, due to the penetration of indenter during the Vickers indentation process allows to estimate the fracture toughness by means of different empirical formulations, which involve the type and length of the cracks with the fracture toughness of materials. However, such formulations are based in specific materials, which were used to determine the value of the coefficients of the equation. For all above in this work is developed a formulation, which establish a better approximation of the fracture toughness of the borided layer Fe2B using the finite element method together with dimensional analysis of the Vickers indentation fracture technique by means of numerical simulation of the Vickers indentation test with help of the commercial software ABAQUS 6.8.2, with the goal of obtaining a formulation, which contained representative coefficients of the hardness layers by boron diffusion.