from Gotthard Wolf, Wolfram Stets and Ulrich Petzschmann, Düsseldorf, Germany:
The paper presents the results of a research project at the IfG in Düsseldorf during the last 2 years. The item of the activities was to investigate and evaluate the cumulative effects of carbide promoting elements on the microstructure and the properties of heavy-section castings made of ferritic cast iron like ENG-JS-400-15. The five selected carbide promoting elements manganese, chromium, niobium, vanadium and boron were varied in two levels. The result was an experimental design of 25 = 32 trials. From each alloy were cast samples with different solidification conditions. On the specimen were evaluated the microstructure and mechanical properties. The generated data base with information about chemical composition, features of microstructure and also of the static, dynamic and cyclic mechanical properties and the fracture mechanics was analysed by multiple regression. As the main result of the project the paper presents regression equations for the formation of carbides and pearlite depending on the chemical composition on the one hand and for the influence of the structural constituents on the mechanical properties otherwise. During the project were used different software programs to calculate the carbide formation in complex cast iron alloys.