Additive Manufacturing of Metals: Microstructure, Properties and Alloy Development: Ni-based Alloys II
Program Organizers: Prashanth Konda Gokuldoss, Tallinn University of Technology; Jurgen Eckert, Erich Schmid Institute of Materials Science; Zhi Wang, South China University of Technology
Tuesday 8:00 AM
October 11, 2022
Room: 302
Location: David L. Lawrence Convention Center
Session Chair: Jeferson Pacheco, Federal University of Parana
8:00 AM
Material Qualification of IN625 for Binder Jet Printing: Katerina Frederick1; Kyle Myers1; 1Desktop Metal / ExOne
Inconel 625 material for fully dense single alloy binder jet printing was qualified for printing with a Desktop Metal InnoventX system through a series of testing both in-house and through a third party. Powder was tested prior to printing to determine process parameters based on powder size distribution and flow characteristics. Several builds were completed using the InnoventX qualification print layout to account for build-to-build variation. Parts were sintered and heat treated externally before physical and mechanical testing. Final relative densities were 99%+ and physical and mechanical properties fell within UNS specifications. The composition of the alloy was also within specifications for an Inconel 625 alloy. As a result, the alloy was qualified for use in the InnoventX system and a datasheet with expected mechanical and physical properties was published.
8:20 AM
Origin and Evolution of Defects during Sintering in Binder-Jet Printed 625 Alloy: Chuyuan Zheng1; Markus Chmielus1; Ian Nettleship1; 1University of Pittsburgh
When applied to powder metals, binder-jet 3D printing creates porous green structures where different defect types co-exist and may survive sintering. Previous work illustrated a variety of defects introduced during printing process, but how each type of defect evolves during sintering and to what extent the defect survives remain unclear. In this work, three-dimensional characterization using micro-computer tomography is applied to binder-jetted and subsequently sintered Inconel 625 alloy powders. Integrated 3D analyses along with 2D pore orientation analysis reveal the origin of different defect types during printing, and quantitatively describe their existence in the microstructure as a function of sintering conditions. Moreover, 3D measurements also provide critical data to establish a 3D microstructure pathway for the sintered binder-jetted powder metal.
8:40 AM
Thermal and Microstructural Characterizations of GRCop-84/In718 Composite Structure Fabricated by DED Machine: Zexiao Wang1; Nicholas O'Brien1; Nicholas Jones1; Jack Beuth1; Sheng Shen1; 1Carnegie Mellon University
Inconel 718 is a widely used nickel based super alloy with excellent high temperature strength and creep resistance. However, its low thermal conductivity limits its use in applications requiring heat exchange and thermal energy conversion. GRCop-84, as a copper-based alloy, has very high thermal conductivity, which may be used in composite materials to compensate for Inconel 718’s low thermal properties. In this work, Direct Energy Deposition (DED), an additive manufacturing technique, is used to create a GRCop-84/In718 composite structure under different combinations of laser power and velocity. The resulting microstructures are investigated by scanning electron microscopy (SEM) and energy dispersive X-ray spectroscopy (EDS). The thermal properties of the composite are also characterized by a frequency-domain thermoreflectance (FDTR) measurement.
9:00 AM
An Investigation into the Effects of CoAl2O4 Oxide Addition on Melt Pool Geometry and Microstructure in Alloy 718 Processed by Laser Powder Bed Fusion: I-Ting Ho1; Kai-Chun Chang2; Dhruv Tiparti1; An-Chou Yeh2; Sammy Tin3; 1Illinois Institute of Technology; 2National Tsing Hua University; 3The University of Arizona
This investigation aims to elaborate on the microstructural evolution of Alloy 718 blended with CoAl2O4 oxide particles and processed by laser powder bed fusion (L-PBF) in terms of melt pool geometry and grain structure. The findings indicate that the addition of CoAl2O4 particles appeared to reduce the melt pool width while increase the melt pool depth by inhibiting the degree of heat transfer and Marangoni flow. The changes in melt pool physics enhanced the tendency for epitaxial growth and hence retarded the columnar-to-equiaxed transition that was affirmed by samples processed using 3 different laser scan speeds. The physical presence of oxide particles was also found to improve the relative density and surface roughness of the bulk samples by generating better metallurgical bonding to the subsequent layers. Preliminary results will be presented and discussed.
9:20 AM
Electron Beam Powder Bed Fused Haynes-282 Builds Containing Thin Wall Struts of Varying Thicknesses: Bryan Lim1; Hansheng Chen1; Keita Nomoto1; Zibin Chen2; Amy Clarke3; Sophie Primig4; Xiaozhou Liao1; Sudarsanam Babu5; Andrew Breen1; Simon Ringer1; 1The University of Sydney; 2The Hong Kong Polytechnic University; 3Colorado School of Mines; 4The University of New South Wales; 5University of Tennessee, Knoxvile
Residual stresses in additively manufactured Ni-based superalloys impact the mechanical performance of as-fabricated parts. Though electron beam powder bed fusion (E-PBF) can produce components with minimal defects and residual stresses, these are often non-zero and significant, due to the inherent variations in thermal signature along the build direction. Here, we present the residual stress distribution measured via neutron diffraction in an as-fabricated Haynes 282 build containing internal cube voids and thin wall struts of varying thicknesses. Complementary local hardness measurements and multi-scale microscopy were used to investigate the influence on structure-property relationships. Observed variations in hardness were rationalised with residual stress distributions and microstructural phenomenology.
9:40 AM
Optimizing the High Temperature Mechanical Performance of Haynes 282 Printed via Laser Powder Bed Fusion: Nicholas Lamprinakos1; Anthony Rollett1; 1Carnegie Mellon University
The microstructures of metal parts produced via additive manufacturing (AM) are often very different than those produced by other methods such as casting or forging. Oftentimes, the as-built AM parts are strongly textured and thus have anisotropic mechanical properties. While for many applications this may be undesirable, there are certain cases, such as when creep must be limited, in which this could be advantageous. In this work, the superalloy Haynes 282 was printed via laser powder bed fusion. The effect of process parameter selection on microstructure and high temperature mechanical properties was studied, with a focus on developing highly textured microstructures. Experimental heat treatments were performed to determine a heat treatment cycle that could preserve the original texture of the AM parts while also allowing the desired precipitate structure to form. A modified Potts model was also utilized to predict the printed microstructure based on the input process parameters.
10:00 AM Break
10:20 AM
Post-heat Treatment Design of Haynes 282 Alloys Processed by Wire-arc Additive Manufacturing: Luis Ladinos Pizano1; Soumya Sridar1; Wei Xiong1; 1University of Pittsburgh
Solution heat treatment is applied to additively manufactured components to minimize texture, relieve residual stress, and reduce segregation. However, grain coarsening during this process also introduces strength deduction, which requires a proper design of both temperature and time for solubilization. In this work, we have systematically studied the effect of solubilization on grain structure, residual stresses and hardness of Haynes 282 samples printed by wire-arc additive manufacturing with two different scanning patterns: single-bead and meander. We observed a dependency of recrystallization behavior on scanning patterns during post-heat treatment. Samples with a single bead melting pattern experience higher cooling rates resulting in higher residual stresses. Therefore, the recrystallization process occurs at a lower temperature compared to the samples with a meander scanning pattern. The single bead sample treated at 1250°C for 2 h shows the greatest homogeneity while, the meander sample exposed to 1300 for 2 h is the most homogeneous.
10:40 AM
Solving Solidification Cracking in Laser Powder Bed Fusion Haynes 230: Jonah Klemm-Toole1; Ruben Ochoa1; Benjamin Rafferty1; Amy Clarke1; Jeremy Iten1; 1Colorado School of Mines
Haynes 230 is a wrought solid solution strengthened Ni-based alloy that exhibits excellent high temperature strength, oxidation resistance, and weldability with traditional arc welding processes. However, when processed with laser powder bed fusion (LPBF) additive manufacturing (AM), significant solidification cracking is observed. In this presentation, we show how we have eliminated solidification cracking in LPBF Haynes 230 by controlling nucleation and promoting equiaxed dendritic solidification. The crack-free microstructures we produce exhibit excellent strengths and ductilities at elevated temperature, enabling the addition of Haynes 230 to the library of materials processible with LPBF. We discuss our approach in the context of solidification models that predict why Haynes 230 exhibits solidification cracking in LPBF, but not in arc welding, as well as why other Ni-based alloys such as IN718 and Haynes 282 do not exhibit cracking in LPBF.