Pouring temperature of nodular cast iron

It is recommended that the optimum spheroidizing temperature range is 1420-1480 ℃, the spheroidizing temperature of nodular cast iron is lower than 1420 ℃, the spheroidizing reaction is insufficient, and the spheroidizing is poor or even non spheroidizing; The spheroidizing temperature is higher than 1480 ℃, the molten iron reacts violently and consumes too much magnesium. At the same time, if the holding time is too long at high temperature, the solidification and crystallization of nodular cast iron will be blocked, the graphite will be coarse, and there will be too much burning loss of effective elements in spheroidizing agent and inoculant, resulting in the decline of spheroidization, as well as the loss of inoculation conditions due to the lack of oxygen and impurities in molten iron.

The pouring temperature shall consider the quality and wall thickness of nodular cast iron and other factors. The pouring temperature of thick and large parts can be appropriately low, but the minimum temperature shall not be lower than 1280 ℃; The pouring temperature of thin-walled parts shall be higher than 1350 ℃. Practice has proved that 1280-1250 ℃ is a dangerous pouring temperature zone, in which pores are most likely to form.