Evaluation of structural isotropy of Cr-V ledeburitic steel made by powder metallurgy of rapidly solidified particles

A microstructure with a particular focus on carbides amount in PM ledeburitic cold work tool steel VANADIS 6 was analysed in three independent directions using the linear quantitative method, in order to determine the anisotropy of the material.The obtained quantitative results were analysed by statistical methods.To obtain sufficiently large statistical files, twenty-five micrographs were acquired from each direction, using the scanning electron microscopy working in both the secondary electron detection mode and the backscattered electrons detection regime.The obtained results infer that there is no significant difference between the quantities of carbides in three independent directions.In other words, the material is isotropic with a probability of 95 %, hence, the initial orientation of semi-product can be disregarded in sampling.A significant difference in measured amounts of carbides was established between two detection regimes used for the quantification.Thereby it was confirmed that the backscattered electrons detection regime has lower resolution limit than the mode of detection of secondary electrons.K e y w o r d s : isotropy of material, statistical hypothesis testing