Journal
MATERIALS SCIENCE AND ENGINEERING A-STRUCTURAL MATERIALS PROPERTIES MICROSTRUCTURE AND PROCESSING
Volume 644, Issue -, Pages 32-40Publisher
ELSEVIER SCIENCE SA
DOI: 10.1016/j.msea.2015.06.021
Keywords
Inconel 718; Selective laser melting; Standard heat treatment
Categories
Funding
- Beijing Natural Science Foundation [Z140002]
Ask authors/readers for more resources
Inconel 718 superalloy has been fabricated by selective laser melting technology (SLM). Its microstructure and mechanical properties were studied under solution+aging (SA) standard heat treatment, homogenization+solution+aging (HSA) standard heat treatment and as-fabricated conditions. Precipitated phases and microstructures were examined using OM, SEM, TEM and X-ray analysis methods. The fine dendrite structures with an average dendrite arm spacing of approximately 698 nm accompanying some interdendritic Laves phases and carbide particles can be observed in the as-fabricated materials. After standard heat treatments, dendrite microstructures are substituted by recrystallization grains, and Laves phases also dissolve into the matrix to precipitate strengthening phases and delta particles. The test values of all specimens meet Aerospace Material Specification for cast Inconel 718 alloy, and the transgranular ductile fracture mode exists for the three conditions. The strength and hardness of heat-treated SLM materials increase and are comparable with wrought Inconel 718 alloy, whereas their ductility decreases significantly compared with the as-fabricated material. This is because of the precipitation of fine gamma' and gamma '' strengthening phases and needle-like delta phases. For the as-fabricated alloy, the formation of finer dislocated cellular structures that develop into a ductile dimple fracture shows excellent ductility. Due to dislocation pinning from gamma' and gamma '' strengthening phases and the impediment of dislocation motion caused by the needle-like 5 phases, the ductility of the SA materials decreases and causes a transgranular fracture, compared with the as-fabricated samples. (C) 2015 Elsevier B.V. All rights reserved.
Authors
I am an author on this paper
Click your name to claim this paper and add it to your profile.
Reviews
Recommended
No Data Available