定電位電解選択腐食法による球状黒鉛鋳鉄中の非金属介在物の観察

抄録

  Cast iron was melted in a high frequency induction furnace from electrolytic iron and electrode graphite. The melt was treated with Fe-Si-Mg (20.62%Mg) alloy at 1,530°C and was cast to a 6mm thick plate using CO₂ mold. C and Si contents were 3.8% and 2.8%, respectively. The potential-current density of the specimens was measured by the potentiostatic electrolysis method in order to select a suitable electrolytic potential. Ferritizing heat treatment was given by heating the as-cast specimens at 900°C for 1h and 720°C for 4h in order to eliminate cementite which interfered with the observation of inclusions, because of its high potential. The selective potentiostatic etching by electrolytic dissolution method (SPEED) was used to expose the inclusions for observation. Titanium phosphide, dice-shaped Ti (C, N), non-metallic inclusions containing Mg, Al, Si, O and those containing Ti, Ce, Si, P and S were three-dimensionally observed and identified by SEM-EDX analysis.