Laser powder bed fusion of Inconel 718 on 316 stainless steel

Journal Article · Sun Aug 09 00:00:00 EDT 2020 · Additive Manufacturing

DOI:https://doi.org/10.1016/j.addma.2020.101500· OSTI ID:1776833

Chen, Wei-Ying ^[1]; Zhang, Xuan ^[1]; Li, Meimei ^[1]; Xu, Ruqing ^[1]; Zhao, Cang ^[2]; Sun, Tao ^[3]

---

1. Argonne National Lab. (ANL), Lemont, IL (United States)
2. Argonne National Lab. (ANL), Lemont, IL (United States); Tsinghua Univ., Beijing (China)
3. Argonne National Lab. (ANL), Lemont, IL (United States); Univ. of Virginia, Charlottesville, VA (United States)

The joining of Inconel 718 and 316 stainless steel has notable industrial importance. However, traditional arc-welding has many issues. In particular, the formation of the detrimental Nb-rich Laves phase in the heat affected zone can promote crack initiation and propagation, which leads to poor mechanical properties. The small heat input and the rapid solidification of laser powder bed fusion (PBF) has the potential to suppress this problem. Despite the infancy of the multi-material PBF, it is of interest to investigate the relationship among the process parameter, the microstructure at the materials joining point, and the mechanical performance. In this study, we used high-speed x-ray imaging to in-situ monitor the printing of Inconel 718 tracks on a 316H SS substrate via laser powder bed fusion, followed by post-build characterization and testing with SEM, XRD and nanoindentation. We observed that a higher linear energy density resulted in a more diffused interface and a smaller compositional gradient, but as a trade-off, generated more keyhole pores and thermal cracks. Furthermore, we also showed that the built layer exhibited chemical inhomogeneity at two length scales: a tens-of-mu m-scale compositional vortex due to the melt flow, and a sub-mu m-scale Nb-rich dendritic structure due to the non-equilibrium solidification that led to the formation of the Laves phase. It was inferred that the chemical inhomogeneity may benefit the mechanical properties at the interface by providing more interlocking between the two materials and also by limiting the effect of the brittle Laves phase to potentially short range.

• Research Organization: Argonne National Laboratory (ANL), Argonne, IL (United States)
• Sponsoring Organization: USDOE; USDOE Office of Science (SC), Basic Energy Sciences (BES)
• Grant/Contract Number: AC02-06CH11357
• OSTI ID: 1776833
• Alternate ID(s): OSTI ID: 1647262
• Journal Information: Additive Manufacturing, Journal Name: Additive Manufacturing Vol. 36; ISSN 2214-8604
• Publisher: Elsevier
• Country of Publication: United States
• Language: English

Related Subjects

36 MATERIALS SCIENCE
Metal additive manufacturing
dissimilar metal joining
electron microscopy
laser powder bed fusion
x-ray techniques