Temperature-Induced Enhancement of Tensile Strength of Perforated Ti-6al-4v Sheet Revealed Through Mechanical-Thermal Coupling Quasi-Static Tension

In order to investigate the effect of temperature on the tensile strength of perforated Ti-6Al-4V (TC4) alloy, the tensile mechanical properties of TC4 alloy with various micro-hole array distributions were obtained at a temperature in a range from 20 o C to 500 o C by using a novel mechanical-thermal coupling tensile test instrument developed by ourselves. The experimental results showed that the tensile strength of all types of TC4 alloy specimens decreased with the increase in temperature. The tensile strength of the perforated specimen was 12% lower than that of the solid specimen at room temperature (RT), and the perforated specimens continued to exhibit relatively lower tensile strengths at 180 o C and 340 o C. Abnormally, the tensile strength of the perforated specimen was 5% higher than that of the solid specimen at 500 o C. With the increase of temperature from 20 o C to 500 o C, the fracture mode of the solid specimen gradually changed from equiaxed dimple to shear dimple. Regarding the perforated specimens, the cracks and dimples adjacent to the holes gradually decreased as a function of temperature. The existence of prefabricated holes in the specimens promoted local thermal deformation and dissipated the corresponding thermal stress, which induced a relatively higher tensile strength at an elevated temperature. The relatively lower stress in the gauge section of the perforated specimens obtained through finite element analysis also indicated the temperature-induced enhancement of tensile strength