Improving fatigue durability of SLM Ti-6Al-4V parts by combined ultrasonic impact-electrophysical treatment

The paper deals with the study of fatigue durability of SLM Ti-6Al-4V specimens after post-build combined Ultrasonic Impact– EelectroPhysical Treatment (UIEPT). It is shown that the highest fatigue performance was characteristic for SLM Ti-6Al-4V specimens treated by the mode 1 (with lower pulse frequency and duration). It was revealed that the conducted combined ultrasonic impact – electrophysical treatment slightly changed the internal structure and microhardness. The modification mostly took place in the surface layers while but the straing and pulsed electric current exposure together gave rise to certain heating as well as variation of bulk material properties. It is suggested that the post-build treatment by the selected rational parameters due to favorable combination of mechanical and electro- physical impacts made it possible to reduce residual stresses. It was shown that the post-build treatment at higher values of electric current pulse frequency and duration did not provide efficient increase of fatigue durability. It suggests that increased energy input during the post-build treatment increased the brittleness and induced excess defects and stresses.