Chemical analysis and X-ray diffraction were carried out for residues which were isolated byhydrochloric acid (1+1) from steel specimens killed with aluminum. The results are as follows;
All of the residues isolated from the present specimens are shown to be mixtures of α-aluminaand aluminum oxy-nitride which is in tetragonal structure of δ-alumina type from the analysis oftheir X-ray diffraction patterns. Aluminum oxy-nitride, like alumina, is so stable to mineral acidthat the existence of this kind of oxy-nitride causes lower analytical results of nitrogen by rapid Kjeldahl, s method. In some other studies on aluminum nitride in steel, it has been reported that thenitride seems occasionally to be undissoluble in mineral acids. The authors concluded from this study, however, that the compound containing nitrogen in the residue isolated by mineral acids is aluminumoxy-nitride and not nitride.