The Heat Treatment Parameters and Microconstituent Content Prediction of ADI Based on Fuzzy Subtractive Clustering Method

Abstract

Ductile cast iron was quenched at different austempering temperatures with different isothermal time, so there were austempered ductile iron (ADI) materials with nine different mechanical properties. Their metallographic structures were qualitatively and quantitatively analyzed with scanning electron microscope and X-ray diffraction method. Curves of the relationships between heat treatment parameters, content of retained austenite and carbon content in retained austenite were studied respectively. Models that showed their relationships were built in the base of fuzzy subtractive clustering method to research the rules of isothermal temperatures and time affecting the microconstituent of ADI. The results show that the metallographical matrix structures of ADI become ausferrite, and its mechanical properties are strengthened notably. From the curves and fuzzy models, we knew that the effect of austempering temperature on the component content of ADI was predominant, and austempering time was inferior. Thus, as the temperature increased, the content of retained austenite, carbon content in retained austenite increased markedly. Keywords: ADI, heat treatment parameters, retained austenite, carbon content of retained austenite, fuzzy subtractive clustering model