**6. Mechanical property of AM Ti-6Al-4V (As built)**

UTS and elongation of as-built AM Ti-6Al-4V are summarised into Figure 14 (a) and (b) [29-88]. ASTM requires that as-prepared Ti-6Al-4V should be no lower than 860 MPa in UTS and no lower than 10% in elongation. These two benchmark values are marked in the two figures using dotted lines. These data suggest that, comparatively speaking, EBM is able to provide a combination of good facture strength and good ductility which satisfy the ASTM specifica‐ tions. Ti-6Al-4V made by SLM tends to show the highest fracture strength among the four AM approaches yet the corresponding ductility is the lowest which is mostly below the corre‐ sponding benchmark value (10%). There are no adequate data for LMD but it is reckoned that it should show a similar tendency to that of the SLM due to the similarity between the two processing techniques. Because of poor density (see Figure 6), SLS Ti-6Al-4V normally relies on post treatment such as HIP to achieve good fracture strength as well as ductility.

**Figure 14.** (a) UTS and (b) elongation of as-built Ti-6Al-4V prepared by the various AM techniques [29-88]. Dotted lines in the two figures represent corresponding ASTM specifications.
