Effect of Carbide Precipitation at Austenite Grain Boundary on Crystallography of Grain Boundary Ferrite

摘要

Proeutectoid ferrite (alpha) nucleates at an austenite (gamma) grain boundary holding a near K-S orientation relationship in general with respect to one of the adjacent y grains. There is severe variant selection for grain boundary nucleation often resulting in coarse grain boundary a film after coalescence. It was recently shown that non-specific, irrational orientation relationships are achieved between grain boundary a and y when alloy carbides are present at y grain boundary. On the other hand, the crystallography of intragranular a nucleated at inclusion/precipitate in y is greatly affected by supercooling. However, the effects of supercooling and grain boundary precipitation prior to transformation on the crystallography of grain boundary a have not been studied yet. The present study examines the crystallography of grain boundary a formed at various temperatures with alloy carbides on y grain boundary with electron backscatters diffraction (EBSD) technique.