Texture Strengthening and Fracture Toughness of Titanium Alloy Sheet at Room and Cryogenic Temperatures

Biaxial yield strengths as high as 1.53 times uniaxial yield strength were obtained from burst tests of 6-in.-diameter cylindrical pressure vessels (1 to 2 stress field) fabricated from two textured titanium alloys, Ti-4Al-0.2O and Ti-5Al-2.5Sn ELI. Material nominally 0.020 in. thick was tested at 70, -320, and -423 F. While the Ti-4Al-0.2O alloy generally had superior biaxial smooth properties at the three test temperatures, the Ti-5Al-2.5Sn ELI alloy exhibited less notch sensitivity at-320 and -423 F. It is demonstrated that plastic Poisson's ratio obtained from a uniaxial test could be used to characterize the degree of texture in the two alloys and provide a means for predicting biaxial strengthening.