Experimental Investigation on Quasi-Freckle Phenomenon in Single-Crystal-Blade Castings of Superalloys
Year: 2024
Type: article
Abstract: During the production of single-crystal superalloy blades, a kind of channel-type defect, named “quasi-freckle”, was found on the casting surface, which is similar to typical freckles in macroscopic appearance but different in microstructure. In the as-cast microstructure of the quasi-freckle channels, the γ/γ’ eutectic is significantly accumulated and can be dissolved during the solution heat treatment. Since no disoriented grains were detected, the quasi-freckles have a basically identical crystal orientation with the matrix. The quasi-freckle channels actually appear as thermosolutal convection traces in the directional solidification process of single-crystal casting. Because the convection was not strong enough to break dendrite arms, the single-crystal consistency of the castings was not destroyed. However, with the deterioration of the solidification condition and the increase in solutal convection, quasi-freckles often develop into typical freckle defects.
Source: Metals
DOI: 10.3390/met14101129
Institution: Central South University
Language: English
Subfield: Mechanical Engineering
Field: Engineering
Domain: Physical Sciences
Open Access status: gold
Estimated APC paid: $2,955
OpenAlex ID: W4403140047