Three-dimensional Grain Size Distribution in SUS304 Stainless Steel

We disintegrated an annealed SUS304 stainless steel bar into separate crystal grains, and measured the distribution of the volume-equivalent grain diameter (the three-dimensional grain size distribution) by weighing the individual grains. We also measured the distribution of the area-equivalent grain diameter (the two-dimensional grain size distribution) on a cross section of the steel bar. From this two-dimensional grain size distribution, the three-dimensional grain size distribution was calculated by the method previously proposed by the authors. The measured and the calculated three-dimensional grain size distributions were then compared. The measured three-dimensional grain size distribution was approximately log-normal. The variation coefficient of the distribution (the standard deviation divided by the average value) was 0.4, and the ratio of the maximum grain size to the average size was about 3.0. The calculated three-dimensional grain size distribution was very similar to the measured one, indicating that the method of calculation previously proposed by the authors yields accurate results.