コールドボックス中子による鋼鋳物のガス欠陥

概要

論文の詳細を見る
Application of phenol urethane cold box cores to steel castings is often associated with gas defects like pinholes. This effect of the cold box cores on the defects was clearly indicated by the experiments in which the same steel melt was poured into molds with cold box cores or CO2 process cores, that is, much more pinholes were observed in the castings when cold box cores were used. The concentration of nitrogen in the samples obtained from the portions close to the pinholes was much higher than those in other portions of the casting. Mass spectrometric analysis of the gases evolved from the cold box, CO2 process and Shell mold process (resol-type) core sands was performed in the temperature range from 600°C to 1,400°C. As the cold box core sands were heated, the solvent of the binder for them volatilized firstly, followed by the evolution of NH3, CO2, CO, H2O and various kinds of hydrocarbon compounds produced by the decomposition of the binder. In the gases from other core sands, NH3 was not detected. It is concluded that the pinholes were caused by the reaction between cast steel and NH3 evolved from the cold box cores. Thermodynamic calculation indicates that the nitrogen pressure of NH3 is very high, and then liquid steel can absorb large amount of nitrogen from NH3.
Japan Foundry Engineering Societyの論文