Creep Analysis of Ti-600 Alloy at 600°C

摘要

Creep tests were carried out on Ti-600 alloy at the temperature of 600°C, and with the stresses of 150MPa, 200MPa, 250 MPa, 300 MPa and 350 MPa, respectively. Steady state creep rate and the stress exponent n at different stresses were calculated for the alloy. Threshold stress σ_0 was introduced to get the true stress exponent p. Creep deformation mechanism was also investigated. The results indicated that the steady state creep rate will increase with the rise of stress, and the creep time will be shortened at the same time. At 600°C, the threshold stress is 76.1MPa. The value of n and p is 2.4 and 1.1 respectively for the alloy crept at lower stress region (150-200MPa); and which is 7.4 and 4.1 respectively for the alloy crept at higher stress region (200-350MPa). Constitutive equations of steady state creep rate were established for the alloy crept at 600°C. The creep deformation mechanism for the alloy is grain boundary diffusion one (Coble creep mechanism) at lower stress region, and which is dislocation climbing mechanism controlled by lattice diffusion (Weetman creep mechanism) at higher stress region.