Ferrite grain refinement in low carbon Cu-P-Cr-Ni-Mo weathering steel at various temperatures in the (alpha plus gamma) region

摘要

Self-designed Cu-P-Cr-Ni-Mo weathering steel was subjected to compression test to determine the mechanism of ferrite grain refinement from 750 degrees C to 925 degrees C. Optical microscopic images showed that ferrite grain size declined, whereas the ferrite volume fraction increased with increasing compression temperature. Electron back scatter diffraction patterns revealed that several low-angle boundaries shifted to high-angle boundaries, thereby generating fine ferrite grains surrounded by high -angle boundaries. Numerous low-angle boundaries were observed within ferrite grains at 750 degrees C, which indicated the existence of pre-eutectoid ferrite. Results showed that ferrite grain refinement could be due to continuous dynamic recrystallization at 750 degrees C and 775 degrees C, and deformation-induced ferrite transformation could be the main mechanism at 800 degrees C and 850 degrees C. Fine equiaxed ferrite grains with size ranging from 1.77 mu m to 2.69 mu m were produced in the (alpha + gamma) dual phase region. (C) 2016 Elsevier Inc. All rights reserved.