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Improvement in the Mechanical Properties of Additively Manufactured Ni–Co‐Based Superalloy by Tailoring Microstructures
Author(s) -
Lee Jung-Uk,
Kim Young-Kyun,
Kim Seong-Soo,
Lee Kee-Ahn
Publication year - 2021
Publication title -
advanced engineering materials
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.938
H-Index - 114
eISSN - 1527-2648
pISSN - 1438-1656
DOI - 10.1002/adem.202100136
Subject(s) - materials science , superalloy , microstructure , substructure , alloy , carbide , dislocation , selective laser melting , metallurgy , phase (matter) , composite material , structural engineering , chemistry , organic chemistry , engineering
Herein, a Ni‐Co‐based superalloy is manufactured using selective laser melting (SLM), and the effects of heat treatment (direct aging [DA] and solution treatment + aging [STA]) on the microstructure and mechanical properties of an SLM‐built Ni–Co‐based superalloy are investigated. An electron channeling contrast (ECC) image of the as‐built alloy shows a substructure where nm‐sized carbides are present along with a dislocation network. In the DA alloy, the basic characteristics of the substructure do not change, but the dislocation density decreases, the carbide fraction increases, and a large number of γ′ phases are formed. On the other hand, the STA alloy has very low dislocation density and exhibits γ′ phases with a size and fraction similar to those of the DA alloy. Room temperature compression tests are conducted, and the yield strengths of the as‐built, DA and STA alloys are 480, 837.5, and 750 MPa, respectively. The main underlying mechanism of improvement in the mechanical properties after heat treatment can be explained by the change of dislocation density and the fraction of carbide and γ′ phase. Based on the abovementioned findings, this study discusses the relationship between the microstructure and mechanical properties of the SLM‐built Ni–Co‐based superalloy.