To explain the intrinsic mechanism of the yield plateau phenomenon in commercially pure titanium, the tensile behaviors of commercially pure titanium specimens after 91.6% cryorolling and subsequent annealing at 280 °C, 335 °C, 450 °C and 600 °C have been studied. The results show that the yield plateau phenomenon is a result of dislocation behaviors controlled by grain size and thus only exists within a given range of mean grain size. α grain boundaries are the main dislocation multiplication sources of commercially pure titanium. Fine-grained microstructure could offer numerous dislocation multiplication locations during deformation. Once the applied stress is above the yielding strength, dislocations multiply rapidly and the mobile dislocation density is high. To retrieve the imposed strain rate, the mean dislocation velocity is bound to be low. Therefore, it takes time for them to interact with each other. As a result, the movement of dislocations is hardly blocked and the deformation could continue at a nearly constant applied stress. Consequently, the so-called yield plateau behavior presents in the tensile curves. The disappearance of yield plateau phenomenon in coarse-grained and ultrafine-grained microstructures is attributed to the quick realization of the mutual interactions among dislocations at the initial stage of tensile test.

为了解释商业纯钛中屈服平稳现象的内在机理，研究了商业纯钛试样在91.6％的冷轧后在280°C，335°C，450°C和600°C退火后的拉伸行为。结果表明，屈服平稳现象是位错行为受晶粒尺寸控制的结果，因此仅在给定的平均晶粒尺寸范围内存在。α晶界是商业纯钛的主要位错倍增来源。细晶粒组织可以在变形过程中提供许多位错倍增位置。一旦施加的应力超过屈服强度，位错迅速增加，并且移动位错密度很高。为了恢复施加的应变速率，平均位错速度必然较低。因此，它们彼此交互需要花费时间。结果，几乎不阻止位错的运动，并且变形可以在几乎恒定的施加应力下继续。因此，在拉伸曲线中存在所谓的屈服平稳行为。