Discontinuous dynamic recrystallization (DDRX), which involves multiple nucleation and grain growth processes, plays a crucial role in grain refinement; however, the underlying mechanism and the significant role of twin boundaries (TBs) remain poorly understood. Here, the evolution of characteristic microstructures and the fraction and density of TBs under different deformation conditions (i.e., 1050–1200 °C, 0.001–1 s⁻¹) in Incoloy 825 was investigated through a thermomechanical simulator, electron backscattered diffraction (EBSD), and transmission electron microscopy (TEM). The first strand of recrystallized grains nucleated along the original grain boundaries (GBs), separated by the newly formed random high-angle grain boundaries (HAGBs), which were transformed from low-angle grain boundaries (LAGBs) and pre-existing TBs. Subsequently, straight TBs forming in the new grains increased the misorientation angle, promoting the migration of stagnated grain boundaries, and parts of newly generated twinning chains at the front of the recrystallization zone converted into random HAGBs, providing sites for the following layer of nucleation. Moreover, triple junctions between the recrystallized and deformed grains also served as potential nucleation sites when the LAGBs in the large misorientation gradient were transformed into random HAGBs. Quantitative relationships between the recrystallized grain size and TB density were obtained.

涉及多个成核和晶粒生长过程的不连续动态再结晶（DDRX）在晶粒细化中起着至关重要的作用。但是，人们对孪生边界（TB）的潜在机制和重要作用仍然知之甚少。在这里，在不同变形条件下（即1050–1200°C，0.001–1 s ^-1），特征微结构的演变以及结核菌的分数和密度通过热机械模拟器，电子背散射衍射（EBSD）和透射电子显微镜（TEM）研究了Incoloy 825中的）。第一条再结晶晶粒沿原始晶界（GBs）成核，并被新形成的随机高角度晶界（HAGBs）隔开，而高角度晶界由低角度晶界（LAGBs）和预先存在的TB转变而来。随后，在新晶粒中形成的直TB增大了取向差角，促进了停滞的晶界的迁移，并且在重结晶区前部的新生成的孪生链的一部分转化为随机的HAGB，从而为下一个成核层提供了位置。此外，当大取向错误梯度中的LAGBs转变为随机HAGBs时，重结晶和变形晶粒之间的三重连接也可作为潜在的成核位点。获得了再结晶晶粒尺寸与TB密度之间的定量关系。