Abstract
Utilizing the Magnetic analysis with specimens of less than 27.8% Cr and 1.55% C, the change of the transformation point due to the cooling conditions was studied, and several diagrams showing the composition range in which the transformation is lowered and its change due to the cooling conditions were proposed. The microstructure of these specimens and its change due to the cooling conditions were examined, and structural diagrams showing the relation between the composition of specimens and the microstructures in 4 cases cooled from 900° and 1, 100° in furnace and in air, respectively were constructed. Based on these diagrams the effects of carbon and chromium contents in specimens, the cooling rate and the maximum heating temperature on the microstructure were elucidated. By examining the microstructure of several specimens which were carburized and cooled under several conditions the effect of carbon on the microstructure was studied, and the correctness of the structural diagrams obtained above was confirmed.
