19Cr-13Ni-3Si鋼の高温酸化におよぼす希土類元素添加の影響

抄録

Effect of addition of rare earth metals (REM) up to 0.06% to Fe-19Cr-13Ni-3Si alloys containing 0.002 to 0.008% sulfur on their oxidation behavior at temperatures from 1 000 to 1 200°C in air has been investigated by thermogravimetry, metallography, X-ray diffraction, EPMA, and chemical analysis.
(1) Good correlation between the oxidation resistance and the REM/S is found. With an increase of the REM/S, the oxidation resistance is improved under both cyclic and continuous oxidizing conditions.
(2) In case of the low REM/S, the oxidation resistance decreases because of early formation of Fe rich oxide and Si internal oxide grows markedly into substrate.
(3) In case of the high REM/S, REM concentrate in the inner scales and the continuous layer of Si oxide is formed beneath Cr₂O₃ layer, and consequently the protective scale is retained much longer.
(4) Effect of REM on the improvement of the oxidation resistance seems that REM concentrate in Cr₂O₃ scales and make Cr₂O₃ scales more protective. REM in solution except fixed REM to sulfide are effective.