Effects of temperature on tensile and fracture performance of Ti6Al4V alloy fabricated by laser powder bed fusion

Research on low temperature resistance and fracture behavior of additively manufactured (AMed) titanium alloy is lacking. In this study, both tensile and fracture behavior of Ti6Al4V alloy produced by laser powder bed fusion (LPBF) were investigated at four temperatures (293, 223, 173, 123 K). Microscopic observation and finite element analysis were used to study the fracture mechanism. A correlation of fracture toughness and temperature between 123 and 293 K was obtained. As the temperature decreases, the fracture mode of the specimen changes from ductile fracture to a mixed mode of ductile and brittle fracture, the tensile strength increases and the fracture toughness decreases. These differences could be interpreted by the crack tip plastic zone (CTPZ) and microscopic plastic deformation. Compared to the wrought Ti6Al4V alloy, the fracture originations are mainly from LPBF defects, i.e., lack of fusion (LOF) defects and gas pores.