Abstract

The post-dynamic recrystallization behavior of ultrafine-grained (UFG: 0.44 μm) cp-Ti under annealing, room temperature (RT) monotonic and cyclic loading was investigated across a range of temperatures and deformation rates wherever appropriate. By characterizing the grain and boundary structures, it was confirmed that recrystallization and grain growth occurred due to annealing (≥ 600 °C) and R = − 1 fatigue at RT. There was a noticeable 30 deg aggregation in misorientation distribution, along with the increased grain size. However, the hypothetical correlation between 30 deg aggregation and Σ13a or the other characteristic coincidence site lattice boundaries was found to be weak. The fatigue-induced grain growth is particularly intriguing for two reasons. First, the large monotonic deformation with low strain rate cannot trigger grain growth. Second, fatigue sharpened the basal intensity around the ND and caused a weaker texture component close to TD (load axis along the LD, perpendicular to the TD–ND plane). By contrast, high-temperature annealing only strengthened the UFG processing induced basal pole but without affecting its location. Novel insights into this fatigue-induced texture evolution in UFG cp-Ti has been provided. The lattice rotation during fatigue can be attributed to the combined effect of activation of prismatic \( \langle a\rangle \) slip parallel to LD, and basal \( \langle a\rangle \) slip perpendicular to it. The theoretically calculated stress to activate dislocation slip by assuming a non-equilibrium grain boundary state lent support to the above assertion. Moreover, the TEM observation evidently showed the characteristics of dislocation cross-slip and multiple slip in the grain interior.

Graphical Abstract

中文翻译：

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后动态再结晶钛在退火，单调和循环载荷下的微观结构和织构演变

摘要

的动态交再结晶行为超细颗粒（UFG：0.44 μ m）因退火CP-Ti系，室温（RT）单调和循环加载量在一定范围的温度和变形率酌情的调查。通过表征晶粒和边界结构，可以确认由于退火（≥600°C）和R导致了再结晶和晶粒生长=-1 RT疲劳。取向错误的分布有明显的30度聚集，同时晶粒尺寸也增加了。但是，发现30度聚集与Σ13a或其他特征重合位点晶格边界之间的假设相关性较弱。疲劳引起的晶粒长大特别有趣，原因有二。首先，具有低应变率的大单调变形不能触发晶粒长大。其次，疲劳加剧了ND周围的基础强度，并导致靠近TD（沿着LD的载荷轴，垂直于TD-ND平面）的纹理分量变弱。相比之下，高温退火只会增强UFG加工诱导的基极，而不会影响其位置。已经提供了有关UFG cp-Ti中疲劳引起的织构演变的新颖见解。\（\ langle a \ rangle \）平行于LD滑动，而基础\（\ langle a \ rangle \）垂直于LD滑动。通过假设非平衡晶界状态为上述论断提供了理论上计算出的激活位错滑移的应力。此外，透射电镜观察清楚地表明了晶粒内部错位的横向滑移和多次滑移的特征。

图形概要