open access

https://hdl.handle.net/2115/96165

Hall-Petch strengthening of an Fe-C-Cr-Ni eutectic alloy under additive manufacturing conditions

英語

Additive manufacturing

2025-10-11

Elsevier

Journal of Alloys and Compounds

1043

184213

This paper deals with Hall-Petch strengthening of an Fe-based eutectic alloy that is applicable to the additive manufacturing. This alloy consists of a dual-phase structure of a γ-Fe (Ni) matrix and ∼20 vol% of eutectic chromium carbide rods. The distance between the eutectic carbide rods or rod spacing was varied over a wide range from ∼101 to ∼10−2 μm by varying cooling rate during solidification from ∼10−1 to ∼107oC/s. This wide variety of the cooling rate was provided by a variety of cooling methods of the liquid alloy, including slow furnace cooling of the liquid in an alumina crucible, arc melting and fast cooling of a button-like small ingot in a graphite crucible, rapid cooling of small melt pools formed on the surface of the ingot samples using a TIG welder, and extremely rapid cooling of fine melt pools formed on the surface of the ingot samples using a laser scanner. As the rod spacing decreased from ∼101 to ∼10−2 μm, Vickers hardness of the as-solidified alloy increased from ∼300 to ∼600 HV. This considerable increase in hardness was due to the Hall-Petch effect, and the relation between the Vickers hardness, HV, and the rod spacing, λ, was described as a regression equation of HV =67.4 λ−1/2 +305 with a high correlation coefficient of R2 =0.9009. When this alloy was applied to the laser powder bed fusion, the as-built prototype exhibited a high Vickers hardness of ∼720 HV, more than twice that of Inconel 718 Ni-based superalloy produced using the same process.

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