Effect of Heat Treatment on Microstructure Evolution and Mechanical Properties of Selective Laser Melted Inconel 718 Alloy
- 42 Downloads
The microstructure characteristics of the selective laser melted Inconel 718 alloy under as-deposited, homogenization + solution + aging (HSA) and solution + aging (SA) conditions were studied. The anisotropy and heterogeneity of mechanical properties under different conditions were also investigated. Under the as-deposited condition, the morphology and size of the grains are heterogeneous. The dendrite structures which grow nearly perpendicular to the molten pool traces, accompanying interdendritic Laves phase, can be observed within the grains. The dendrite structure completely disappeared, and the Laves phases embedded in the interdendritic regions also dissolved into the matrix to precipitate γ′ and γ″ phases after heat treatments. Fully recrystallized grains were obtained under the HSA condition, while only incomplete recrystallized grains were obtained under the SA condition. However, the characteristics of γ′ and γ″ phases are very similar under the HSA and SA conditions. Significant improvement in strength after heat treatments was due to the dissolution of undesirable Laves phase and the precipitation of γ′ and γ″ phases. For all the three conditions, different tensile properties were observed depending on the orientation of the specimens. The scatter of mechanical properties is notable, and heat treatments increased the scatter of mechanical properties.
KeywordsInconel 718 alloy mechanical properties microstructure selective laser melting
This work was supported by Supported by National Key R&D Program of China (2017YFB0305100) and Fundamental Research Funds for the Central Universities (Grant No. 21618325).
- 3.S.S. Babu, N. Raghavan, J. Raplee, S.J. Foster, C. Frederick, M. Haines, R. Dinwiddie, M.K. Kirka, A. Plotkowski, Y. Lee, and R.R. Dehoff, Additive Manufacturing of Nickel Superalloys: Opportunities for Innovation and Challenges Related to Qualification, Metall. Mater. Trans. A, 2018, 49(9), p 3764–3780CrossRefGoogle Scholar
- 4.R.C. Roger, The Superalloys: Fundamentals and Applications, 2012.Google Scholar
- 8.W.D. Huang and X. Lin, Research Progress in Laser Solid Forming of High-Performance Metallic Components at the State Key Laboratory of Solidification Processing of China, 3D Print, Addit. Manuf., 2014, 1, p 156–165Google Scholar
- 26.W. Kurz and D.J. Fisher, Fundamentals of Solidification, Trans Tech Publications, 1986.Google Scholar
- 28.J.F. Radavich, The Physical Metallurgy of Cast and Wrought Alloy 718, Metall. Appl., 1989, 718, p 229–240Google Scholar
- 31.G.H. Cao, T.Y. Sun, C.H. Wang, X. Li, M. Liu, Z.X. Zhang, P.F. Hu, A.M. Russell, R. Schneider, D. Gerthsen, Z.J. Zhou, C.P. Li, and G.F. Chen, Investigations of γ′, γ″ and δ Precipitates in Heat-Treated Inconel 718 Alloy Fabricated by Selective Laser Melting, Mater. Charact., 2018, 136, p 398–406CrossRefGoogle Scholar