Cold creep of titanium: Analysis of stress relaxation using synchrotron diffraction and crystal plasticity simulations

Heterogeneous Deformation in a Commercially Pure Titanium Sheet under Dwell Fatigue Loading: Crystal Plasticity Modeling and Experiment

“…Since increased concentration of oxygen can improve the strength of CP-Ti for the solid-solution strengthening effect, and the strengthening effect of oxygen is reported to be more remarkable on prismatic slip than basal slip, the CRSS ratio between basal and prismatic slips is therefore decreases with increased amounts of oxygen. 35,36) Moreover, the macroscopic strength of tested grade 1 CP-Ti in the present study is between the counterparts reported by Hama et al 8) and Xiong et al 33) In terms of these relationships, the initial CRSS basal /CRSS prismatic in this study is optimized between 1.63 and 2.14, values reported by the abovemen-…”

“…The activation energy ΔF for each slip system is 0.5447 eV, which is slightly smaller than the value of prismatic slip reported by Xiong and co-workers. 33) The activation volume ΔV is 26b 3 , the same as the value calibrated by Gong et al 9) between 8b 3 -80b 3 , a general range for titanium and its alloys. 38) The reference shearing rate  γ 0 and rate sensitive index r for twinning systems are taken to be  γ 0 = 0.001 and r = 0.05, respectively.…”

“…Recently, Xiong et al have found that the SRS of prismatic slip is higher than that of basal slip in a grade 4 CP-Ti and the activation energy ΔF of basal slip is also greater than that of prismatic slip, similarly to Ti-6242 alloy. 33,34) Although slip-dependent SRS variations are considered to have influence on creep deformation in cold dwell fatigue, the concrete mechanisms are still unknown. Besides, the diversity in chemical compositions should not be ignored.…”

Weighted ellipse fitting routine for spotty or incomplete Debye-Scherrer rings on a 2D detector

“…As a part of the larger experiment, various Ti samples under were deformed under tensile load in-situ using an Instron Electro-Thermal-Mechanical Tester (ETMT) system (described elsewhere in (Xiong et al, 2020;Xiong et al, 2021)). A schematic of the setup is shown in Figure 2(a).…”

“…The image acquisition time per pattern was fixed at 1 s and the incident beam size was set to 1 × 1 mm 2 on a sample of thickness 1 mm. This weighted ellipse approach has already been used to evaluate the lattice strains for several other reflections in four different cp-titanium grades, the results of which are available elsewhere (Xiong et al, 2020;Xiong et al, 2021).…”