Study on small crack growth behavior of laser powder bed fused Ti6Al4V alloy

Abstract

The small fatigue crack growth (FCG) behavior in Ti6Al4V alloy manufactured by selective laser melting (SLM) was experimentally investigated on an in situ fatigue testing machine. A semi-elliptical artificial defect was introduced into the specimen to simulate the pore defects induced during additive manufacturing (AM) process. The results indicated that the fatigue life was mainly consumed in the small FCG stage. The FCG rate was significantly affected by microstructure at the early small FCG stage with great fluctuations. With the increase of crack length, the effect of microstructure decreased. Compared with long crack growth data, it was found that small crack can still grow below the threshold value of long crack, and at the same stress intensity factor (SIF) ΔK, the FCG rate of small crack was higher than that of long crack. Therefore, the small crack growth behavior should be considered in fatigue life prediction for SLM Ti6Al4V.

Effect of heat treatment on the variable amplitude fatigue life and microstructure of the novel bioinspired Ti‐6Al‐4V thin tubes fabricated using Selective Laser Melting process

“…All these studies show that the fatigue performance of the SLM-printed Ti-6Al-4V is entirely different from the other standard (α-β) Ti-6Al-4V, which affects both the static and dynamic life of the components. [14][15][16][17] Furthermore, studies on the fatigue behavior of SLM-printed Ti-6Al-4V lattice structures are limited. 18,19 Different methods have been used to enhance the fatigue life of the SLM-printed Ti-6Al-4V components like heat treatment, sand-blasting, and surface modification.…”

“…There have been many studies on the compressive fatigue behavior of the selective laser melting (SLM)‐printed Ti‐6Al‐4V component. All these studies show that the fatigue performance of the SLM‐printed Ti‐6Al‐4V is entirely different from the other standard (α‐β) Ti‐6Al‐4V, which affects both the static and dynamic life of the components 14–17 . Furthermore, studies on the fatigue behavior of SLM‐printed Ti‐6Al‐4V lattice structures are limited 18,19 .…”