RESEARCH ON A NEW PROCESS OF LOW-TEMPERATURE ANNEALING OF MALLEABLE CAST IRON AND THE THEORY OF ITS GRAPHITIZATION.

If proper inoculation is used before casting, malleable cast iron of a ferritic matrix is produced by annealing the white cast iron at temperature below the eutectic point, 760 degree C, for 20-30 hours. This new process is superior to the traditional method in which ferritic malleable iron is obtained by annealing at high and low temperature in succession, through two stages of graphitization. Comparing the traditional two stage graphitization with the new process, the energy consumed will be decreased by 25% and the oxidation and distortion of castings will also be decreased. The machinability will be improved to some extent.