Compared with gray cast iron, the tensile strength of vermicular graphite cast iron is increased by about 80%, the elastic modulus is increased by about 40%, and the fatigue strength is nearly doubled. In recent years, vermicular graphite cast iron has been rapidly developed and widely used at home and abroad. At present, more than 50000 engine blocks are produced every month in the world, including Audi, Daimler, Ford, Volkswagen, Volvo and other manufacturers of passenger and commercial vehicles. At present, the factories producing vermicular iron castings in China mainly adopt the wire feeding method and the punching method. Because the punching method is not stable and easy to control, the vermicular rate is not easy to stabilize above 80%. ZHY Casting adopts SinterCast large vermicular treatment system to develop 16L vermicular cast iron cylinder block and study its production process to achieve stable process control and quality stability.
Through reasonable chemical composition design and alloying treatment, high temperature graphitized low sulfur carburetor is used to improve the carburetion effect. Silicon carbide is used for pretreatment to increase the nucleation ability of molten iron. The superheat temperature of molten iron is increased to 1 540~1 550 ℃, and the temperature is kept for 20 minutes. The purity of molten iron is improved. The vermicularization and inoculation treatment is carried out at 1 480~1 490 ℃ to ensure good vermicularization effect, so that the produced vermicular iron cylinder blocks G, Y The creep rate at the three sampling positions of Z is more than 80%. The creep rate at different wall thickness positions is slightly different. The creep rate at G and Z positions is slightly higher than that at Y positions. The tensile strength of the three sampling positions G, Y and Z of the vermicular graphite cast iron cylinder block is more than 420 MPa, and the hardness is 230~260 HBW.