Session: Rising Stars of Mechanical Engineering Celebration & Showcase

Paper Number: 148553

148553 - Creep Performance of Gas Metal Arc Directed Energy Deposition Haynes 282 

Future clean power generation technologies will require advanced manufacturing processes to produce high-performance components locally and quickly. Additive manufacturing based on automated gas metal arc welding, or gas metal arc directed energy deposition (GMA-DED), can produce large components with high deposition rates and has the potential to provide flexibility and accelerated production needed to support the energy infrastructure. However, the lack of a comprehensive understanding of how processing conditions affect the material's microstructures and the high-temperature mechanical properties hinders the adoption of GMA-DED. A National Science Foundation (NSF) Faculty Early Career Development (CAREER) award supports an integrated experimental and modeling approach to develop a mechanistic link between processing conditions (during additive manufacturing and required post-processing) and crucial microstructural features that dictate high-temperature creep and fatigue performance of a precipitation hardened Ni-based superalloy, Haynes 282. This CAREER grant also supports the development of courses on “Solidification” and “Physical Metallurgy of Welding and Additive Manufacturing” at Colorado School of Mines as well as a joint capstone project between welding students and engineering students to build mutual respect.

In this presentation, the first creep results of GMA-DED are presented. A collaborative robot controlled Fronius TPS 400i gas metal arc heat source was used to produce wall-shaped builds using Haynes 282 wire feedstock. Builds were direct one step aged to replicate the heat treating strategy developed for large Haynes 282 components. The microstructure of the builds was evaluated using scanning electron microscopy (SEM) and electron backscatter diffraction (EBSD) in the as-build and heat treated condition. In the as-built condition, the microstructure exhibited coarse columnar grains parallel to the build direction with an average grain size of over 1 mm. After the aging heat treatment, the grain morphology was unchanged, but a heterogenous distribution of gamma prime precipitates were observed with different sizes and number densities in dendrite cores and interdendritic regions. Creep testing at 760 °C revealed that specimens extracted perpendicular to the build direction showed rupture times equivalent to wrought Haynes 282, while specimens extracted parallel to the build direction showed creep lives greater than that of wrought. An analysis of minimum creep rate as a function of stress showed that similar creep mechanisms are dominant in GMA-DED, wrought, and welded Haynes 282. Ultimately, the superior creep life of GMA-DED Haynes 282 is likely due the large grain size compared to wrought counterparts, which is in alignment with predictions of creep rupture life models. The results of this work show that GMA-DED is a strong candidate to produce structural components in high temperature structural applications and may provide the rapid production capability need to support future power generation technologies.  

Presenting Author: Jonah Klemm-Toole Colorado School of Mines

Presenting Author Biography: Dr. Jonah Klemm-Toole joined the Metallurgical and Materials Engineering (MME) department as an Assistant Professor in Fall 2020. Jonah became interested in metallurgy through learning how to weld at a local community college during high school. Jonah worked as a welder throughout high school and during his undergraduate education in the Materials Science and Engineering Department at the University of Florida (UF). After graduating from UF in 2008, Jonah’s welding experience helped him get a job at Power Systems Manufacturing in Jupiter Florida to work on welding, brazing, chemical processing, heat treating, and coating of Ni and Co based superalloy castings for industrial gas turbine components. After working at PSM for 5 years, Jonah decided to continue his education at Colorado School of Mines by pursuing a PhD focused on alloy design for improved fatigue performance of nitrided gear steels. Jonah stayed at Mines to work on advanced in-situ characterization of solidification relevant to additive manufacturing as a Post-Doctoral Fellow. Now, Jonah is an Assistant Professor at Colorado School of Mines focusing on welding and additive manufacturing of metals for demanding high temperature structural applications.

Authors:

Sophie Hill Colorado School of Mines
Jonah Klemm-Toole Colorado School of Mines