The initial stage of the rapid solidification of 18Cr-8Ni stainless steel has been numerically analysed using the cooling curves at the sample surface obtained in the experiments. Heat transfer coefficient between the chill substrate and the samples is determined by fitting the calculated cooling curves to experimental ones.
In the vicinity of the surface, there exists the region where growth rate and temperature gradient are very large. The length of the region is nearly equal to that of the initial solidification structure of samples. The solidification conditions in the sample are estimated and the relation between secondary dendrite arm spacing and cooling rate is obtained.