Numerical study on the formation of spurious grains and freckles during the directional solidification of superalloys
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2023. Paper presented at MCWASP XVI IOP Conf. Series: Materials Science and Engineering.
Research output: Contribution to conference › Paper › peer-review
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T1 - Numerical study on the formation of spurious grains and freckles during the directional solidification of superalloys
AU - Zhang, Zhao
AU - Wu, Menghuai
AU - Liu, Xiaoshan
AU - Song, Min
AU - Ludwig, Andreas
AU - Kharicha, Abdellah
N1 - This work was financially supported by the Austrian Science Fund in the framework of the FWF-NKFIN joint project (FWF, I4278-N36).
PY - 2023
Y1 - 2023
N2 - Freckles, a significant issue encountered during the directional solidification of superal-loys, are recognised by a trail of equiaxed grains parallel to the direction of gravity accompanied bylocal eutectic enrichment. In the current study, a mixed-columnar-equiaxed multiphase volume-av-erage solidification model was employed to study the formation of freckles in superalloy casting.Fragments produced via flow-driven and capillary-driven fragmentation mechanisms are consideredas the source of spurious grains. The transport and the growth/remelting of the fragments are consid-ered. According to the simulation results, some segregation channels develop at the corners of thecasting. Flow-driven fragments are produced in/around the segregation channels, whereas capillary-driven fragments are produced at a certain depth of the mushy zone across the entire section of thecasting. The fragmentation rate caused by the flow-driven mechanism is several orders of magnitudelarger than that caused by the capillary-driven mechanism, i.e. the flow-driven fragmentation mech-anism is dominant for the currently investigated sample. After the solidification process, four frecklesformed at the casting corners on the shadowed side, whereas it was freckle-free on the bright side.
AB - Freckles, a significant issue encountered during the directional solidification of superal-loys, are recognised by a trail of equiaxed grains parallel to the direction of gravity accompanied bylocal eutectic enrichment. In the current study, a mixed-columnar-equiaxed multiphase volume-av-erage solidification model was employed to study the formation of freckles in superalloy casting.Fragments produced via flow-driven and capillary-driven fragmentation mechanisms are consideredas the source of spurious grains. The transport and the growth/remelting of the fragments are consid-ered. According to the simulation results, some segregation channels develop at the corners of thecasting. Flow-driven fragments are produced in/around the segregation channels, whereas capillary-driven fragments are produced at a certain depth of the mushy zone across the entire section of thecasting. The fragmentation rate caused by the flow-driven mechanism is several orders of magnitudelarger than that caused by the capillary-driven mechanism, i.e. the flow-driven fragmentation mech-anism is dominant for the currently investigated sample. After the solidification process, four frecklesformed at the casting corners on the shadowed side, whereas it was freckle-free on the bright side.
KW - formation of spurious grains
KW - formation of spurious grains and freck- les
KW - spurious grains and freck- les
KW - directional solidification
KW - superalloys
U2 - 10.1088/1757-899X/1281/1/012059
DO - 10.1088/1757-899X/1281/1/012059
M3 - Paper
T2 - MCWASP XVI IOP Conf. Series: Materials Science and Engineering
Y2 - 18 June 2023 through 23 June 2023
ER -
