Yttrium modifying influence on the shape and amount of nonmetallic inclusions in the austenitic high alloy steel

Yttrium influence on the form and amount of non-metallic inclusions in steel 06H23N18M5 was studied. It has been found that yttrium binds oxygen and other elements into heterogeneous compounds, it resulting in the transition of impurities into passive state. Oxide inclusions, sulfide inclusions and globules formed as a result of steel components reactions with oxygen, sulfur and nitrogen dissolved in metal are mostly found in the structure. It was found that by modifying and refining austenitic steels with yttrium service properties of the deposited layer can be ad-justed. X-ray diffraction and X-ray spectrum analysis revealed that the modified steel 06H23N18M5 + 0.02% Y has a heterogeneous structure with uniformly distributed inclusions of σ-phase and composite carbides (Fe, Cr, Mo) 23C6. It is possible that Y modification resulted in the appearance of chemically resistant intermetallic σ-phase in these steels, for nucleation was facilitated by increasing the number of crystallization centers as dispersed primary yttrium oxy-sulfide compounds