On morphologies, microsegregation, and mechanical behavior of directionally solidified cobalt-base superalloy at medium cooling rate

Effect of Cooling Rate on the Solidification Microstructure and Characteristics of Primary Carbides in H13 Steel

“…Fernandez et al 11) analyzed the effect of cooling rate (between 4.98 × 10 − 2 and 1.07°C·s − 1 ) on the growth geometry of MC carbide in IN-100 dendritic monocrystals and found carbide coarsen as cooling rate increases. Chu et al 12) investigated characteristics of a cobalt-base superalloy at a medium cooling rate from 38 to 60°C·s − 1 and found that, the dendrite segregation is suppressed and the size of carbide decreases as cooling rate increases. Previous studies have investigated the effect of cooling rate on the morphology and distribution of carbide as well.…”

“…The reason of this phenomenon could be ascribed to the fact that as cooling rate increased, the growth of the primary carbides was suppressed because the local solidification time and the space of interdendritic region decreased. 12) But the shape of the primary carbides was determined by the shape of interdendritic region, hence it was insensitive to cooling rate. The area covered by the primary carbides were also analyzed and the result is plotted in Fig.…”

Effect of Pressure on Dendrite Structure and Characteristics of Carbides during Solidification Process of H13 Die Steel Ingot

“…The main reason is that there is comparatively sufficient time and space for MC and M 2 C to grow with decrement in cooling rate and increment in dendrite arm spacing from edge to center. 34,41) With increasing pressure from 0.1 to 2 MPa, the mean area of MC and M 2 C decreased. The decrement in mean area of M 2 C at the edge was large than that at the center, and decrements of mean area of MC were roughly equal.…”

“…With increasing pressure, there exists the increment in cool- ing rate and decrement in SDAS. Therefore, the increment in pressure leads to the insufficient time and space for the growth of MC and M 2 C. At the same time, with increment in cooling rate and decrement in SDAS, the insufficient degree of growth time and space are larger at the edge than those at the center for MC and M 2 C. 28,41) It results that the decrement in the mean area of carbides at the edge is greater than that at the center.…”

“…It indicates that there exist decrements in element segregation caused by the decrease of cooling rate from the edge to the center. 41) When the equilibrium partition coefficient is less than 1, the larger equilibrium partition coefficient will decrease the segregation. 26) Thus, the SR of Cr is smallest.…”