By strictly controlling the chemical composition, melting process, spheroidizing inoculation process and casting modulus of nodular iron, high-quality nodular iron with different as cast structure was prepared. The nodularization rate of graphite was more than 80%, the number of graphite balls was not less than 170 / mm2, and the grade of graphite ball diameter was ≥ 6. The as cast structure should contain mainly P and P+ α mixed matrix, mainly α, and no precipitation of intergranular carbide, phosphorus eutectic, sulfur eutectic and other compound phases.
(1) The as cast nodular iron with different matrix structure is treated by austenitizing and water quenching under different process parameters, and then the carbon content in the as cast and water quenched structure is detected by electron probe microanalyzer. The change law of carbon content in austenite of nodular iron after austenitizing is studied, and the optimal austenitizing parameters of nodular iron are obtained.
(2) The microstructure of Austempered Ductile Iron at different isothermal transformation temperatures was observed and analyzed, and the isothermal transformation mechanism of austemperedwas studied.
(3) The mechanical properties of Austempered Ductile Iron Prepared by different process factors were investigated.