Rheocast structure in a hypoeutectic high chromium white iron

Microstructural stress concentration: An important role in grain refinement of rheocasting structure

“…Various rheocasting structures have been reported, [11][12][13][18][19][20][21] and these rheocasting structures have a common feature: equiaxed dendrites are like grape clusters. In these clusters, coarse dendrite arms join together by relatively thin roots, as shown in Figure 1.…”

“…[12] This type of morphology is very susceptible to stress concentration. After comprehensively considering the studies of Gillibate et al, Tönhardt et al, and Das et al, [22,23] as well as the rheocasting structures observed directly through experimentation, [11][12][13][18][19][20][21][22][23][24][25] a dendrite model composed of a stem and a side branch was conceived. The dendrite branch and the primary dendrite stem of the dendrite model were simplified to two perpendicular cylinders of diameters 2R 1 ϭ 40 m and 2R 2 ϭ 70 m, respectively, as shown in Figure 2(a).…”

“…1-Two typical equiaxed austenite dendrites in rheocasting hypoeutectic high chromium white iron with solute-enriched subgrains separating the stems and the branches. [12] The numbers marked on the upper-left corner are the angle of the subgrain boundaries: (a) quenched without isothermal stirring and (b) isothermally stirred for 30 s. Only the resultant fluid force on the upstream surface of the dendrite branch, dF y /dS, was considered. The central section was treated as a symmetrical area.…”

“…[7][8][9][10][11][12][13][14] It is generally accepted that grain refinement in agitated semisolid slurries is caused by dendrite fragmentation. Disagreement arises over the question of how dendrite branches detach.…”