Abstract: The relationship of as-cast austempered ductile cast iron with alloy additions and the effects of alloys on matrix structures in various modules of casting have been examined. The alloy equivalent-module-matrix structure diagram and corresponding calculation formula have been given after sythesizing the functions of Ni, Cu, Mo and Si. The effects of Ni, Cu and Si on mechanical properties have been also examined. On this base, the author has made the methmatic statistic analysis with the effect of alloy combination on the mechanical properties and by this, the corresponding formulas are obtained. In order to control as-cast matrix structures, the CCT - diagram and cooling curves in varies modules have been measured. Besides, the toughness-temperature, the fracture toughness and the effect of the tempering heat treatment have been also examined. The results of the examination indicate that it is possible to obtain as-cast austempered ductile iron by adding alloys. To Y25 standard probe, with proper amount of alloys, the tensile strength up to 90 kg/m m2 With elongation up to 3% can be obtained. The low temperature (-40℃) toughness (ISO V-type probe) is up to 4.6J.The fracture toughness is up to 175 kg/mm3/2 and after tempering at 325℃, the 20% higher can be obtained. The results indicate that the retained austenite is good to mechanical properties.

Key words: 奥-贝铸铁, 合金铸铁, 铸态铸铁