Effect of solution heat treatment on the microstructure and crystallographic texture of IN939 fabricated by powder bed fusion-laser beam

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Date
2023-05-19
Authors
Doğu, Merve Nur
Özer, Seren
Yalçın, Mustafa Alp
Davut, Kemal
Bilgin, Mert Güney
Obeidi, Muhannad Ahmed
Brodin, Håkan
Gu, Hengfeng
Brabazon, Dermot
Journal Title
Journal ISSN
Volume Title
Publisher
Journal of Materials Research and Technology
Abstract
The effect of various solution heat treatment temperatures (i.e., 1120, 1160, 1200 and 1240 °C) on the microstructure, grain morphology and crystallographic texture of IN939 fabricated by powder bed fusion-laser beam (PBF-LB) was investigated. Microstructural analyses showed that the high-temperature gradient and rapid solidification of the PBF-LB processing caused different resulting microstructures compared to conventionally produced counterparts. The melt pool morphologies and laser scanning paths were examined in the as-fabricated samples in the XZ- and XY-planes, respectively. After the application of solution heat treatment at 1120 °C, the as-fabricated PBF-LB initial microstructure was still apparent. For solution heat treatments of 1200 °C and above, the melt pool and scanning path morphologies disappeared and converted into a mixture of columnar grains in the XZ-plane and equiaxed grains in the XY-plane. On the other hand, large equiaxed grains were observed when the samples were solutionized at 1240 °C. Additionally, γ' phase precipitated within the matrix after all solution heat treatment conditions, which led to increase in the microhardness values. According to electron backscatter diffraction (EBSD) analyses, both as-fabricated and solution heat-treated samples had intense texture with {001} plane normal parallel to the building direction. The first recrystallized grains began to appear when the samples were subjected to the solution heat treatment at 1160 °C and the fraction of the recrystallized grains increased with increasing temperature, as supported by kernel average misorientation (KAM) and grain spread orientation (GOS) analyses.
Description
Open Access, Published by Journal of Materials Research and Technology, https://doi.org/10.1016/j.jmrt.2023.05.152, Merve Nur Doğu, Muhannad Ahmed Obeidi, Dermot Brabazon, Form, the SFI Research Centre for Advanced Manufacturing, Dublin City University, Dublin, Ireland, School of Mechanical & Manufacturing Engineering, Dublin City University, Dublin, Ireland, Advanced Processing Technology Research Centre, Dublin City University, Dublin, Ireland, Mustafa Alp Yalçın, Metal Forming Center of Excellence, Atılım University, Ankara, Turkey, Seren Ozer, Department of Metallurgical and Materials Engineering, Atılım University, Ankara, Turkey, Department of Metallurgical and Materials Engineering, Middle East Technical University, Ankara, Turkey, Güney Mert Bilgin, Department of Metallurgical and Materials Engineering, Middle East Technical University, Ankara, Turkey, Kemal Davut, Department of Materials Science and Engineering, Izmir Institute of Technology, 35430, Urla, Izmir, Turkey, Håkan Brodin, Siemens Energy AB, Slottsvägen 2-6, 612 83 Finspång, Sweden, Hengfeng Gu, Ansys Inc., 1441 W Ute Blvd, Suite 335, Park City, UT 84098, USA, Corresponding author Merve Nur Doğu: mervenur.dogu@dcu.ie
Keywords
Solution heat treatment, PBF-LB, IN939, Microstructure, Texture, Recrystallization
Citation
http://hdl.handle.net/20.500.14411/1895