形变热处理工艺参数对冷轧态镍基高温合金晶界特征分布演变的影响

Influence of thermal-mechanical processing parameters on grain boundary character distribution evolution in a cold-rolled Ni-based superalloy

摘要:

本文研究了不同形变热处理工艺参数对冷轧态镍基高温合金中晶界特征分布演变的影响。结果表明，在退火处理过程中，生长事故模型是静态再结晶(SRX)晶粒中新Σ3晶界形成的主要机制。随着退火时间和退火温度的增加，晶界迁移时间延长，晶界迁移速度加快，从而增加了生长事故的发生频率，促进了Σ3晶界的形成。此外，随着应变的增加，Σ3晶界的比例先减小后增大。在冷轧变形量为0.1和0.7时，Σ3晶界的比例均可达到60%左右，这与大晶粒团簇的形成密切相关。此外，本文还详细分析了不同工艺参数下，Σ1晶界、共格Σ3晶界、非共格Σ3晶界、Σ9晶界、Σ27晶界和随机晶界的演变规律。

Abstract:

The influence of thermal-mechanical processing (TMP) parameters on the grain boundary character distribution evolution in a cold-rolled Ni-based superalloy was studied. During annealing treatment, growth accident model was considered to be the main mechanism for the formation of new Σ3 boundaries in the SRX grains. With the increasing annealing time and temperature, there was more time for grain boundary migration and the grain boundary migration was faster at the higher annealing temperature, which could stimulate the formation of Σ3 boundaries by increasing the frequency of growth accidents. In addition, the fraction of Σ3 boundaries decreased firstly with the increasing strain, and then increased again. At the strains of 0.1 and 0.7, the fractions of Σ3 boundaries reached around 60%, which was related to the well development of large grain-clusters. Besides that, the evolution of Σ1 boundaries, coherent Σ3 boundaries, incoherent Σ3 boundaries, Σ9 boundaries, Σ27 boundaries, and random boundaries were also analyzed in detail.