Estudio de fatiga a bajos ciclos de la aleación Ti-6Al-4V obtenida por fusión de haz de electrones y su extensión a altos ciclos

Abstract

Electron beam fusion (EMB) is an Additive manufacturing (AM) technique used to produce parts by melting metal powder layer by layer with an electron beam under high vacuum conditions, thus generating a 3D topology that allows complex configurations that are very difficult to obtain with conventional manufacturing methods. This paper describes the low cycle fatigue behavior for samples of Ti-6Al-4V alloy obtained by EBM and its extension to high cycle fatigue. Cylindrical specimens machined under the ASTM E8 were used, then they were subjected to tensile tests, on a universal MTS Bionix® machine. The results allowed to establish the static conditions: yield stress of 1023 MPa, and a maximum stress of 1143 MPa, as well as a maximum strain of 13%. Fatigue tests were performed at approximately a load inversion ratio R = -1 under controlled displacement. The range of cycles to breakdown was up to 13335 cycles. These results were plotted in a strain vs. number of cycles to failure (Ɛ -Nf) curve using two versions of the Coffin-Manson rule. The two rules are rules for Ti and Al alloys and one of these is exclusive for Ti-6Al-4V alloys printed by AM. Finally, high cycle fatigue data for the same alloy and manufactured by EBM were appended to data from this research seeking an adjustment to a Manson-Coffin-Basquin model-type-of rule, which resulted in ε_t= 0.0364N ^-0.148.