Abstract: Focusing on the key component of automotive turbochargers—Ti Al alloy turbine, the microstructural factors and mechanical characteristics of the turbine failed during its overspeed test were explored. The experiment employed Ti-47.5 Al-2.5 V-1.0 Cr（at%） titanium-aluminum alloy, and turbine samples were prepared using a centrifugal casting process. Overspeed tests were conducted under specific rotational speed conditions, and the tensile property testing and microstructure observation were carried out for the samples taken from the turbine core. The results indicate that the turbine undergoes premature fragmentation failure during the overspeed test, with an average radial tensile strength of 392 MPa at the core, which is only 73% of the material’s intrinsic strength, serving as the primary macro-cause for failure. The angle between the lamellar structure at the crack initiation site and the back surface of the wheel is between 30°-60°, leading to a reduction in local material strength. Based on Griffith’s fracture theory and PST crystal theory, when the angle between the external load and the lamellar orientation is 30°-60°, the PST crystals of Ti Al alloy exhibit the lowest strength, ultimately resulting in the turbine’s overspeed fragmentation failure.