Studies on the Queuched Structure of a Plain Carbon Steel : (4th Report) Observation of the Spherodizing Process of a Plain Carbon Steel during a long Tempering

The steel with various contents of carbon tempered for a long period of time after quenched in the water (10℃). In this case, the present investigators observed the process of spherodizing of carbide for each tempering time. The results obtained are as follows : (1) The higher the tempering temperature is, the more rapid the spherodizing velocity is for the same carbon steel. Especially the low carbon steels have this tendency. (2) The time of spherodizing cementite is shorter for the high carbon steel than the low carbon steel, and the size of spherodizing carbide is larger. (3) The majority of the drop of hardness was done for a very short time, and it was very small to drop the hardness for a long tempering. (4) The dispersion of spherodizing carbides in consequence of tempering for a low carbon steel is better than it done for a long heating of normalized steels.