High Productivity Direct Energy Deposition (DED) Additive Manufacturing (AM) with In-Situ Cryogenic Cooling Control
Abstract
This project aims to develop the fundamental knowledge base that is needed to successfully implement in-situ liquid nitrogen cryogenic cooling (ILNCC) technology in robotic arc directed energy deposition (DED) additive manufacturing (AM) of nickel aluminum bronze. ILNCC has the potential to address two key challenges in arc DED AM technology: low productivity due to long wait times for cooling to interpass temperature, and high residual stresses in large deposits. Nickel aluminum bronze (NAB) is a high value material used in a range of static and dynamic Naval structures (i.e. propellers) that would highly benefit from advances in AM technology. Robotic arc DED AM offers maximum build volume for manufacturing of large-scale metal structures and features. Shipbuilders need agile automation technology for robotic welding, cladding, and AM to build large structures, add features to structures, and repair structures. The gas metal arc pulse (GMA-P) process is widely used in shipbuilding applications. It offers high deposition rates over a wide range of DED features, i.e. single-bead wide “walls” and multi-bead wide walls (or “blocks”) to form shapes. Even though GMA-P DED offers high deposition, the actual duty cycle of the process can be very low. To meet interpass temperature requirements, up to 80% of build time is spent waiting for the build to cool between passes. Forced air, gas or water spray cooling can be used but have limitations for DED AM applications. A more efficient approach is the use of cryogenic cooling for either interpass cooling between deposits or in-situ cooling directly behind the GMA-P torch for maximum duty. In-situ cryogenic cooling with carbon dioxide or liquid nitrogen has shown potential for reducing residual stresses and distortion in welded structures; it is also used to control part temperature in high duty thermal spray applications. While cryogenic cooling has the potential to increase duty cycle and reduce residual stresses and distortion, understanding the effect on build microstructure and properties is key for its use in arc DED AM. Similar to steels, cooling rate plays an important role in phase transformations and resulting phase composition in nickel aluminum bronze (NAB). Rapid cooling rates result in suppression of multiple types of kappa phase precipitates, and formation of martensitic beta prime phase, which is detrimental to mechanical properties. Martensite in NAB alloys has also been associated with preferential corrosion and cavitation erosion. The proposed effort will establish the fundamental process-microstructure-property relationships needed to make high quality, high productivity GMA-P DED AM builds on nickel aluminum bronze. A twofold integrated computational materials engineering (ICME) approach will help direct the experimental research and facilitate the intelligent use of in-situ liquid nitrogen cryogenic cooling (ILNCC) technology: (1) Thermal stress finite element modeling will guide ILNCC setup and parameter selection, and (2) Thermodynamic and kinetic materials modeling will be used to predict NAB microstructure as a function of cooling rate, guide selection of interpass temperature and time/temperature selection for post build heat treatment if needed to restore material properties. The outcome of this project will be a GMA-P DED AM technology with ILNCC for nickel aluminum bronze (NAB) applications with demonstrated increase in productivity, reduction in residual stresses, and build microstructure and property control. This project outcome is directly aligned with the program’s focus areas of supporting advances in new or developing Naval manufacturing technologies, and optimizing materials used in Naval manufacturing.
Document Details
- Document Type
- DoD Grant Award
- Publication Date
- Jun 09, 2021
- Source ID
- N000142112461
Entities
People
- Carolin Fink
Organizations
- Office of Naval Research
- Ohio State University
- United States Navy