Effect of prior deformation on microstructural development and Laves phase precipitation in high‐chromium stainless steel

• Published in: Journal of microscopy (Oxford) Vol. 266; no. 1; pp. 35 - 47
• Main Authors: HSIAO, Z.‐W., CHEN, D., KUO, J.‐C., LIN, D.‐Y.
• Format: Journal Article
• Language: English
• Published: England Wiley Subscription Services, Inc 01.04.2017
• Subjects: Crofer 22 H; EBSD; Laves phase; strain‐induced precipitates; strain-induced precipitates; Crofer 22 H; EBSD; Laves phase
• ISSN: 0022-2720; 1365-2818; 1365-2818
• DOI: 10.1111/jmi.12516

Summary This study investigated the influence of deformation on precipitation behaviour and microstructure change during annealing. Here, the prior deformation of high‐chromium stainless steel was tensile deformation of 3%, 6% and 10%, and the specimens were then annealed at 700˚C for 10 h. The specimens were subsequently analyzed using backscattered electron image and electron backscattering diffraction measurements with SEM. Compared with the deformation microstructure, the grains revealed no preferred orientation. The precipitates of TiN and NbC were formed homogenously in the grain interior and at grain boundaries after annealing. Fine Laves phase precipitates were observed in grains and along subgrain boundaries as the deformation increased. Furthermore, the volume fraction of Laves phase increased, but the average particle diameter of precipitate was reduced as the deformation increased. Lay Description Crofer 22 H ferritic steel with high chromium has been developed for interconnect applications in solid oxide fuel cell at high temperature above 620°C due to ecoenergy and CO2 reduction regulation. Thus, work hardening and solution strengthening are needed for the high‐temperature mechanical properties. Here, the formation of precipitates inhibits recrystallization and grain growth. For example, microalloying elements of Ti, V and Nb have been added to achieve precipitates in HSLA steel. In this study, we focused on the relationship between prior deformation and the behaviour of Laves phase precipitates in Crofer 22 H after annealing. In addition, the deformation microstructure was investigated during annealing using backscattered electron image and electron backscattering diffraction measurements with SEM.