Studies on the Heat Treatment of the Inoculated Cast Iron : The Investigation about the Ca-Si, Fe-Mo Complexly Inoculated Cast Iron by means of the Magnetic Analysis

摘要

It is generally recognized that Ca-Si is effective as inocubnt to make high strength cast iron. The authors already researched on the previous papers that the complex inocu lants, Ca-Si and Fe-Mo were more effective to make strong cast iron. The authors investigated the method to make acicular cast iron by the heat treatment on that inoculated cast iron. From the varions expcrimcnts, the authors gained the following results. The cast iron heated up to the quenching temperature should be cooled rapidly. That cooling velocity must be rapid enough especially while it passes through the temperature of the pearlite transformation range in order to suppress this transformation. Immediately after that pearlite transformation temperature range, the cast iron test piece should be put in the annealing furnace, which is controlled to maintain the temperature range of bainite transformation. And it is necessary to keep the cast iron in that furnace until to finish the bainite transformation perfectly. The authors also recognized that when the pearlite transformation would be suppressed perfectly during that cooling time, the less of the amount of Fe-Mo inoculant, the more rapidly to transform to the bainite structure and the larger quantity of the bainite transformation.