论文标题
温度升高和高强度和高脚度的绝热剪切带的热塑性微结构演变10 wt。％ni钢
Temperature increases and thermoplastic microstructural evolution in adiabatic shear bands in a high-strength and high-toughness 10 wt.% Ni steel
论文作者
论文摘要
由于其高强度，出色的韧性和低凝管至脆性过渡温度（DBTT），已经为高压和低温应用开发了10 wt。％镍钢。但是，在动态载荷条件下，这种钢很容易出现剪切定位，表现为绝热剪切带（ASB）。从宏观长度尺度到采用相关电子 - 叠加剂衍射（EBSD），透射电子显微镜（TEM）和Atom-Probobe-Probobe-probobe（APT）（APT），详细研究了ASB的温度升高和热塑性微结构演化。根据塑料工作向热量产生的转化，在绝热条件下的温度升高计算，ASB中的微观结构过渡是专门讨论的：（i）B.C.C.-F.C.C.相变及其元素分区； （ii）在温度升高期间，V（NB） - 富含碳耐二硫酸盐的组成变化的热力学模型； （iii）通过动态/机械再结晶过程进行晶粒的再填充和旋转。使用Gibbsian界面过剩方法测量的亚晶边界处的溶质分离，揭示了溶质分离如何通过促进溶质元素的下降和晶界的迁移来促进局部剪切形成的不稳定性。最后，通过以下方式描述了ASB内晶粒细化/旋转的动力学模型：（i）亚晶粒形成； （ii）变形旋转/改进； （iii）随着进一步旋转和温度升高，亚晶粒结合的晶粒生长。 ASB中动态变形下的温度升高促进了晶界的迁移和亚晶粒结合，从而产生了大量的等亚晶粒，并且缺陷密度较低。
A 10 wt.% nickel-steel has been developed for high pressures and low-temperature applications, due to its high strength, excellent toughness, and low ductile-to-brittle transition temperature (DBTT). Under dynamic loading conditions this steel is, however, prone to shear localization that manifests as adiabatic shear bands (ASBs). The temperature increases and thermoplastic microstructural evolution in the ASB are studied in detail, from the macroscopic length scale to the atomic-scale employing correlative electron-backscatter diffraction (EBSD), transmission electron microscopy (TEM), and atom-probe tomography (APT). From a calculation of the temperature increase under adiabatic conditions, based on the conversion of plastic-work to heat generation, the microstructural transitions in the ASB are discussed specifically for: (i) a b.c.c.-f.c.c. phase-transformation and their elemental partitioning; (ii) the thermodynamic model for the compositional change of the V(Nb)-rich carbonitride precipitates during a temperature increase; and (iii) grain-refinement and rotation by dynamic/mechanical recrystallization processes. Solute segregation at subgrain boundaries, measured using the Gibbsian interfacial excess methodology, reveals how solute segregation contributes to the instability of localized shear-deformation by promoting the depinning of solute elements and the migration of a grain boundary. Finally, a kinetic model for grain refinement/rotation within an ASB is described by the dynamic recrystallization behavior with: (i) subgrain formation; (ii) rotation/refinement by deformation; and (iii) grain growth by subgrain coalescence with further rotation and a temperature increase. The temperature increase under dynamic deformation in an ASB promotes grain boundary migration and subgrain coalescence to create a large degree of equiaxed grains with a low density of imperfections.
