The quality problems of ductile iron castings can be caused by the following aspects:
1. The raw material production process does not require strict chemical composition;
2. The spheroidization rate standard is not up to the standard and the next process is carried out; the spheroidization rate standard is increased, and the products that meet the standard will enter the next step. One process.
2. Quality defects produced in the casting process: sand inclusion, sand hole, pinhole phenomenon, caused by the mold, the mold needs to be repaired in time.
3. Heat treatment of ductile iron castings; annealing, normalizing, quenching and tempering, and austempering are carried out in strict accordance with the production operation requirements. Annealing can obtain ferrite matrix, improve toughness, plasticity, and eliminate stress; normalizing can obtain pearlite matrix, which improves strength and Wear resistance; quenching and tempering to obtain good comprehensive mechanical properties; austempering to obtain comprehensive mechanical properties such as high hardness, high toughness and high strength, to avoid cracking during heat treatment.