Al脱酸した18-8ステンレス鋼の酸化物系介在物

Abstract

The experiments are aimed to investigate the effects of aluminum content in 18Cr-8Ni-0.9Mn-0.4/0.8Si-Fe stainless steel upon the compositions and the amount of the oxide inclusions and upon their deformation by hot-and cold-rolling. The starting material is the ingot of 10 kg which is prepared in the induction furnace under argon atmosphere. The concentration range of aluminum are from 0.007 to 0.1%. The microscopic examination is used to determine the amount and the size of the oxide inclusions in ingots and their length after rolling. The compositions of inclusions are determined by a X-ray microanalyser and the crystallographic structure is examined by the electron-diffraction method.The following results are obtained.(1) The relation between the concentrations of aluminum and oxygen in molten steel is in well agreement with that of the equilibrium experiments. It is represented by the following equation.(2) As for the ingots containing less than 0.03%Al, the oxide inclusions are Mn-silicate and their amount decreases rapidly with increasing aluminum content. On the other hand, as for the ingots containing more than 0.03%Al, the oxide phase is alumina and the amount dcreases slightly with increasing aluminum content.(3) Mn-silicate is plastically deformed by hot-rolling, but in case of cold-rolling after hot-rolling of the ingots it is crushed and arranged in a dotted line in metallic matrix. Alumina is neither deformed nor crushed by hot-and cold-rolling.