In-situ tensile deformation behavior of powder metallurgy Ti6Al4V alloys

Abstract

In this study, in-situ tensile deformation behavior of powder metallurgy (PM) Ti6Al4V alloys was investigated to analyze the crack initiation and propagation. Accordingly, the fracture mechanisms of the as-sintered and forged PM alloys were summarized. At the initial stage of plastic deformation, cracks appeared in the stress concentration area of pores in the as-sintered Ti6Al4V alloy, and the crack propagation direction was along the phase boundary. Due to the existence of pores, early fracture was obtained, resulting in low elongation of 6.3%. After forging, the crack initiation occurred between α lamellar structure, and the propagation direction was along the lamellar direction. The fine lamellar structure in different directions in the forged PM Ti6Al4V alloy can hinder the crack propagation, thus improving the plasticity. As a result, better comprehensive mechanical performance was obtained in the forged sample, with UTS of 960 MPa, YS of 850 MPa, and EL of 16%.