The shear properties and failure mechanism of TC11 titanium alloy fabricated by laser melting deposition technology

The development of laser melting deposition (LMD) technology has dramatically improved the processing efficiency of complex components of titanium alloys, allowing them to be widely used in aerospace and military equipment fields. Compression tests of double shear specimens at various temperatures and strain-rate ranges from 0.001 s−1to 13,000 s−1 were conducted to study the shear properties and fracture mechanism of LMD TC11 titanium alloy in the scanning and deposition directions. The metallographic structure was observed by optical microscope (OM), while the fracture morphology was characterized by scanning electron microscope (SEM). The results indicate that the plastic flow stress of the material is insensitive to the printing direction. However, the failure strain for this material in the scanning direction is larger than that in the deposition direction, which suggests better plasticity in the scanning direction. Moreover, the material exhibits noticeable strain rate sensitivity and temperature rise softening effect, and the double shear specimens are prone to cracking due to stress concentration at the diagonal of the rectangular shear zone. Given the effect of strain rate on temperature sensitivity, a modified Johnson-Cook (J-C) model was presented. The predicted results showed a good agreement with the experimental results, which can guide the numerical simulation of LMD TC11 titanium alloy. This study also provides a fundamental databank for the application and design of LMD TC11 alloy in manufacturing large and complex structural parts.