低合金鋼のミクロ偏析に関する定量的研究

Abstract

Standard samples were prepared by fully homogenizing a set of low-alloy steels. Then, working curves were made out, demonstrating the relationships between contents of alloying elements and the X-ray intensity with electron-probe microanalysis. Using these working curves, the influence of cooling rate during solidification on the microsegregation of chromium and molybdenum in the interdendrite of a 4-ton commercial steel ingot was measured.In the columnar crystal zone, the effective partition coefficient was approximately constant regardless of the large variation in cooling rate, but the segregation index increased to some extent with decreasing cooling rate.The degree of microsegregation was by far greater in the equiaxed than in the columnar crystal zone. Therefore, it is supposed that the microsegregation arising during solidification depends upon the mode of solidification rather than upon the experimentally measured parameters of solidification such as temperature gradient and freezing rate. The effective partition coefficient was lower in the equiaxed than in the columnar crystal zone.