Molento de Moraes, Carlos EduardoBaptista, Carlos Antonio Reis Pereirados Santos Torres, Marcelo Augusto [UNESP]Fonseca, Maria CindraAbdalla, Antonio Jorge2018-12-112018-12-112016-01-01Materials Science Forum, v. 869, p. 503-507.0255-5476http://hdl.handle.net/11449/168958The AISI 4340 steel has been largely employed for structural purposes, which requires resistance levels with yield strength above 1400 MPa and it attains high levels of resistance in dual phase, bainitic or martensitic microstructural conditions. The samples of AISI 4340 steel with different microstructural conditions (martensitic, bainitic and ferritic/perlitic) have been submitted to fatigue tests on push-pull mode. Subsequently, the new specimens underwent a shot peening surface treatment and new fatigue tests. The results have been discussed in comparison to the three microstructural conditions studied and they were related to a microstructural characterization. The results have showed that a shot peening treatment is not always beneficial to fatigue life, since there is a relationship between the compressive stresses developed on the surface and its roughness formed due to the deformations. Under the three microstructural above studied it was noticed a strong fatigue life reduction in the martensitic condition because such microstructure is considered less ductile.503-507engAISI 4340 steelFatigueMicrostructural characterizationShot peeningTrabalho apresentado em evento10.4028/www.scientific.net/MSF.869.503Acesso aberto2-s2.0-84988328623