Particle Stimulated Nucleation in Coarse-Grained Ferritic Stainless Steel

Abstract

Particle-stimulated nucleation (PSN) is investigated in Nb-containing ferritic stainless steel. Coarse-grained sheets were cold rolled to 80 pct thickness reduction and annealed from 973 K to 998 K (700 °C to 725 °C) to obtain partially recrystallized microstructures. Electron backscatter diffraction was performed around coarse niobium carbonitride particles (larger than 1 μm) within coarse grains (~1 mm), with different host orientations in both deformed and annealed states. In the deformed state, the deformation zones around both spherical and rectangular particles were investigated. The local lattice rotations about the transverse direction necessary to accommodate the particle-matrix strain incompatibility were observed in all grains investigated. After annealing, recrystallization occurs preferentially around coarse particles at the initial stages of recrystallization. Based on a total number of 130 grains nucleated via PSN, we observe both, randomly oriented and minor {111}〈110〉 oriented texture components. The results also reveal that PSN in this material is not associated with a specific host orientation.