Estudo do comportamento das tensões residuais em amostras jateadas de aços inoxidáveis AISI 201LN e AISI 304L

Abstract

Stainless steels are a large family of steels that are used in several applications due to their excellent corrosion resistance and good mechanical properties. Few studies address the residual stresses state and the mechanical properties of 200 series steels when subjected to shot peening treatment, generating phase transformation induced by deformation, since the literature is restricted to the evaluation of deformation caused by rolling. The present work aims to evaluate the residual stresses by X-ray diffraction and by magnetic Barkhausen noise (MBN) in samples of 201LN and 304L steels submitted to shot peening with different treatment times. The results indicate that the increase in the treatment time promotes an increase in the intensity of the compressive residual stresses both in the austenitic matrix and in the ferromagnetic phases, represented by the delta ferrite and the martensite. The MBN technique verified that the new martensite from shot peening has tensile residual stresses represented by signals with high and narrow peaks. In addition, shot peening promoted a significant increase in surface hardness due mainly to the austenite hardening. In contrast, for longer treatment times, a lower increase in hardness is observed, which can be attributed to the effect of the transformation of austenite in martensite.