Grain boundary engineering in a thermo-mechanically processed Nb-stabilized austenitic stainless steel

17th International Conference on Textures of Materials

材料科学;物理学

Yunquera, A.^1 ; Jorge-Badiola, D.^1 ; Gutiérrez, I.^1 ; Iza-Mendia, A.^1

CEIT and Tecnun (University of Navarra), Donostia-San Sebastián, Basque Country, Spain^1

关键词: Annealing twinnings;    Electron back scatter diffraction;    Grain boundary character distributions;    Grain boundary engineering;    Grain boundary migrations;    Random grain boundaries;    Special boundaries;    Thermo-mechanical;   

Others  :  https://iopscience.iop.org/article/10.1088/1757-899X/82/1/012113/pdf
DOI  :  10.1088/1757-899X/82/1/012113

学科分类：材料科学（综合）

来源: IOP

【 摘 要 】

Three different thermo-mechanical strategies - annealing, strain recrystallization and strain annealing - were applied to a Nb-stabilized 304H austenitic stainless steel in order to study their effects on grain boundary character distribution (GBCD). An Electron Backscatter Diffraction (EBSD) analysis revealed specific combinations of cold reduction-temperature-time that favor annealing twinning. A uniform increase in microstructural size and special boundaries (particularly for Σ3, Σ9 and Σ27 boundaries) was achieved under strain annealing conditions (low cold reductions) and long times at high temperatures (≥ 990°C). These conditions provide a high fraction of special boundaries (about 80%), which replace the random grain boundary network and thus optimize the GBCD. The profuse presence of Σ3nboundaries is attributed to the geometric interaction of twin-related variants during grain boundary migration. In addition to all this, precipitation takes place at the temperature range where optimum GBCD is achieved. The significance of precipitation in the different strategies was also tackled.