オーステンパ球状黒鉛鋳鉄の水蒸気による脆化挙動

抄録

  Plastic deformation with wet conditions causes marked embrittlement in austempered ductile cast iron (ADI). We call this behavior “Water Embrittlement effect”. Water molecules exist as water vapor in room air. Tiny amounts of water vapor in air are thought to embrittle ADI. Tensile tests were performed under different relative humidities. The purpose of this study was to examine the effects of water vapor on tensile properties of ADI. The results obtained were as follows : Water vapor in room air caused minute embrittlement in ADI. The increase in partial pressure of water vapor increased the degree of embrittlement. The humidity at which the embrittlement effects appeared clearly was above 50% RH. The increase in the exposure time to water vapor decreased the tensile properties. The embrittlement effect of water vapor may be due to surface reactions on the specimens.