Effect of strain level on the evolution of microstructure in a recently developed AD730 nickel based superalloy during hot forging
Effect of strain level on the evolution of microstructure in a recently developed AD730 nickel based superalloy during hot forging
复制标题
DOI：
10.1016/j.matchar.2018.03.027
复制
发表时间：
2018-05-01
影响因子：
4.7
通讯作者：
Baker, T. N.
中科院分区：
文献类型：
--
作者：
Konkova, T.;Rahimi, S.;Baker, T. N.
对由镍基高温合金制成的具有优异机械性能的高温应用工程零件的微观结构进行设计和控制，要求零件在锻造过程中进行一定的热机械加工。这通常包括在高温下连续应变和退火，随后在较低温度下进行时效热处理。在这项研究中，研究了应变大小对最近开发的 AD730 镍基高温合金热锻造过程中微观结构演变的影响。在锻造材料中观察到显微结构不均匀性，其表现为再结晶基体中大的未再结晶晶粒的形式，观察到其取决于变形水平（即应变大小）。微观结构分析表明，随着施加应变的增加，小角度晶界和亚结构的比例显着减少，这表明随着应变水平的提高，再结晶比例也更高。结论是，较低的应变水平不足以为锻造材料的整个微观结构的完全再结晶提供足够的驱动力。
Design and control of microstructure of engineering parts made from nickel based superalloys with superior mechanical properties for high temperature applications, require the parts to be subjected to certain thermo-mechanical processing during forging. This often includes sequential straining and annealing at elevated temperatures followed by subsequent aging heat treatments at lower temperatures. In this study, the effect of strain magnitude on the evolution of microstructure during hot forging of a recently developed AD730 nickel based superalloy has been investigated. Microstructural heterogeneity was observed in a forged material manifested in a form of large non-recrystallized grains within the recrystallized Matrix that is observed to be dependent on the level of deformation (i.e. strain magnitude). Analyses of microstructure indicated significant reduction in the fraction of low-angle grain boundaries and sub-structures with an increase in the applied strain, suggesting higher fraction of recrystallization with higher levels of strains. It was concluded that the lower strain levels were insufficient to provide enough driving force for complete recrystallization throughout the entire microstructure of the forged material.