Key Considerations for Ductile Iron Castings

Spheroidization Fade: Pouring must be carried out promptly after spheroidization treatment; otherwise, the loss of spheroidizing agents leads to the deterioration of graphite morphology and adversely affects performance. It is recommended to limit the pouring time to within 15 minutes.
Micro-porosity and Shrinkage Cavities: Ductile iron undergoes significant volumetric shrinkage during solidification. Proper placement of risers and chills is required, and the carbon equivalent should be controlled between 4.3% and 4.7% to utilize graphitization expansion for self-feeding.
Heat Treatment Control: The processing window for Austempered Ductile Iron (ADI) is narrow. Precise control of the isothermal temperature (e.g., 230–400°C) and holding time (30–120 minutes) is essential; failure to do so prevents the formation of the desired lower bainite microstructure.