レーザ焼入れされた球状黒鉛鋳鉄の機械的特性について

抄録

Spheroidal graphite cast irons with different microstructures were heat-treated using a CO₂ laser. The microstructures of these specimens were examined by optical microscopy. Wear, Charpy impact and rotating-bending fatigue tests were then conducted on untreated and laser treated specimens. The results obtained were as follows: In the heat-treated surface layer of ferritic matrix cast iron, spheroidal graphites were surrounded by the ringlike martensite phase. The wear resistance of this structure was superior to that of an untreated structure. This wear resistance increased as the amount of martensite phase in the matrix increased. It was observed that the wear resistance of laser treated cast iron with 20% pearlitic phase was equal to that of untreated cast iron with 80% pearlitic phase. On the other hand, the impact strength of laser treated cast iron was inferior to that of untreated cast iron under the Charpy impact test. However, the impact strength of the laser treated cast iron with ferritic matrix was superior to that of untreated cast iron with pearlitic matrix. The fatigue limit of the laser treated cast irons was slightly decreased.