Effect of solidification rate on microstructure and primary carbides of AISI DC 53 cold work tool steel

The solidification behavior of AISI DC 53 cold work tool steel was investigated by means of a cooling curve and its first derivative. Copper and sand wedge-shaped molds were used to obtain various solidification rates. To reveal the cooling rate degree during solidification, the secondary dendrite arm spacing of the steel alloy was examined by scanning electron microscopy (SEM). The solidification rates of each section for both wedge steel samples were calculated by means of the secondary dendrite arm spacing using a research-based empirical relation from the literature. Experiment results revealed that at the tip region of the cast specimen in the copper wedge-shaped mold, the carbide size was 7-8 mu m, where the solidification rate was approximately 4,830 degrees C.s(-1). The greatest carbide size obtained in the upper region of the sand cast wedge-shaped specimen was 250-270 mu m