The Effects of Stress on the Transient Compressive Creep and Dislocations of Ti6321 Alloy at Room Temperature

To clarify the effects of stress on the creep behavior and related dislocations at room temperature, short-time compressive creep tests were carried out on Ti6321 specimens. An electronic universal testing machine (GNT100), combined with scanning electron microscopy (SEM), electron backscatter diffraction (EBSD), and transmission electron microscopy (TEM), was used to evaluate the accumulation of creep strain and the variations in dislocation mobility of this alloy under different stress. The results show that both the creep strain accumulated over a 10 min creep duration and the transient creep rate gradually increase with rising applied stress. Basal dislocations act as the dominant deformation mechanism in Ti6321 alloy. The stress level also exerts a pronounced influence on the dislocation mobility and the resultant dislocation density. EBSD and TEM analyses confirm that the increasing stress gradually disrupts the tangled dislocation arrays, leading to reduction in the average geometrically necessary dislocation (GND) density and shrinkage of dislocation pile-ups. The resultant decrease in internal back stress promotes creep progression. The above findings provide an experimental basis for better understanding of the stress dependence of short-time strain accumulation of Ti6321 alloy during creep tests.