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Title: Preliminary Investigations of Joining Technologies for Attaching Refractory Metals to Ni-Based Superalloys

Abstract

In this study, a range of joining technologies has been investigated for creating attachments between refractory metal and Ni-based superalloys. Refractory materials of interest include Mo-47%Re, T-111, and Ta-10%W. The Ni-based superalloys include Hastelloy X and MarM 247. During joining with conventional processes, these materials have potential for a range of solidification and intermetallic formation-related defects. For this study, three non-conventional joining technologies were evaluated. These included inertia welding, electro-spark deposition (ESD) welding, and magnetic pulse welding (MPW). The developed inertia welding practice closely paralleled that typically used for the refractory metals alloys. Metallographic investigations showed that forging during inertia welding occurred predominantly on the refractory metal side. It was also noted that at least some degree of forging on the Ni-based superalloy side of the joint was necessary to achieve consistent bonding. Both refractory metals were readily weldable to the Hastelloy X material. When bonding to the MarM 247, results were inconsistent. This was related to the higher forging temperatures of the MarM 247, and subsequent reduced deformation on that material during welding. ESD trials using a Hastelloy X filler were successful for all material combinations. ESD places down very thin (5- to 10-{mu}m) layers per pass, and interactionsmore » between the substrates and the fill were limited (at most) to that layer. For the refractory metals, the fill only appeared to wet the surface, with minimal dilution effects. Microstructures of the deposits showed high weld metal integrity with maximum porosity on the order of a few percent. Some limited success was also obtained with MPW. In these trials, only the T-111 tubes were used. Joints were possible for the T-111 tube to the Hastelloy X bar stock, but the stiffness of the tube (resisting collapse) necessitated the use of very high power levels. These power levels resulted in damage to the equipment (concentrator) during welding. It is of note that the joint made showed the typical wavy bond microstructure associated with magnetic pulse/explosion bond joints. Joints were not possible between the T-111 tube and the MarM 247 bar stock. In this case, the MarM 247 shattered before sufficient impact forces could be developed for bonding.« less

Authors:
 [1];  [2];  [3]
  1. Edison Welding Institute, 1250 Arthur E. Adams Drive, Columbus, OH 43221 (United States)
  2. NASA Glenn Research Center, 21000 Brookpark Road, Mail Stop 49-1, Cleveland, OH 44135 (United States)
  3. Ohio Aerospace Institute, 21000 Brookpark Road, Mail Stop 49-1, Cleveland, OH 44135 (United States)
Publication Date:
OSTI Identifier:
20798017
Resource Type:
Journal Article
Resource Relation:
Journal Name: AIP Conference Proceedings; Journal Volume: 813; Journal Issue: 1; Conference: 10. conference on thermophysics applications in microgravity; 23. symposium on space nuclear power and propulsion; 4. conference on human/robotic technology and the national vision for space exploration; 4. symposium on space colonization; 3. symposium on new frontiers and future concepts, Albuquerque, NM (United States), 12-16 Feb 2006; Other Information: DOI: 10.1063/1.2169257; (c) 2006 American Institute of Physics; Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
75 CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND SUPERFLUIDITY; 36 MATERIALS SCIENCE; BONDING; DEFORMATION; FLEXIBILITY; FORGING; HASTELLOY X; INTERMETALLIC COMPOUNDS; LAYERS; MICROSTRUCTURE; POROSITY; PROPULSION; PULSES; REACTOR MATERIALS; REFRACTORY METALS; SOLIDIFICATION; SUBSTRATES; WELDED JOINTS; WELDING

Citation Formats

Gould, Jerry E., Ritzert, Frank J., and Loewenthal, William S. Preliminary Investigations of Joining Technologies for Attaching Refractory Metals to Ni-Based Superalloys. United States: N. p., 2006. Web. doi:10.1063/1.2169257.
Gould, Jerry E., Ritzert, Frank J., & Loewenthal, William S. Preliminary Investigations of Joining Technologies for Attaching Refractory Metals to Ni-Based Superalloys. United States. doi:10.1063/1.2169257.
Gould, Jerry E., Ritzert, Frank J., and Loewenthal, William S. Fri . "Preliminary Investigations of Joining Technologies for Attaching Refractory Metals to Ni-Based Superalloys". United States. doi:10.1063/1.2169257.
@article{osti_20798017,
title = {Preliminary Investigations of Joining Technologies for Attaching Refractory Metals to Ni-Based Superalloys},
author = {Gould, Jerry E. and Ritzert, Frank J. and Loewenthal, William S.},
abstractNote = {In this study, a range of joining technologies has been investigated for creating attachments between refractory metal and Ni-based superalloys. Refractory materials of interest include Mo-47%Re, T-111, and Ta-10%W. The Ni-based superalloys include Hastelloy X and MarM 247. During joining with conventional processes, these materials have potential for a range of solidification and intermetallic formation-related defects. For this study, three non-conventional joining technologies were evaluated. These included inertia welding, electro-spark deposition (ESD) welding, and magnetic pulse welding (MPW). The developed inertia welding practice closely paralleled that typically used for the refractory metals alloys. Metallographic investigations showed that forging during inertia welding occurred predominantly on the refractory metal side. It was also noted that at least some degree of forging on the Ni-based superalloy side of the joint was necessary to achieve consistent bonding. Both refractory metals were readily weldable to the Hastelloy X material. When bonding to the MarM 247, results were inconsistent. This was related to the higher forging temperatures of the MarM 247, and subsequent reduced deformation on that material during welding. ESD trials using a Hastelloy X filler were successful for all material combinations. ESD places down very thin (5- to 10-{mu}m) layers per pass, and interactions between the substrates and the fill were limited (at most) to that layer. For the refractory metals, the fill only appeared to wet the surface, with minimal dilution effects. Microstructures of the deposits showed high weld metal integrity with maximum porosity on the order of a few percent. Some limited success was also obtained with MPW. In these trials, only the T-111 tubes were used. Joints were possible for the T-111 tube to the Hastelloy X bar stock, but the stiffness of the tube (resisting collapse) necessitated the use of very high power levels. These power levels resulted in damage to the equipment (concentrator) during welding. It is of note that the joint made showed the typical wavy bond microstructure associated with magnetic pulse/explosion bond joints. Joints were not possible between the T-111 tube and the MarM 247 bar stock. In this case, the MarM 247 shattered before sufficient impact forces could be developed for bonding.},
doi = {10.1063/1.2169257},
journal = {AIP Conference Proceedings},
number = 1,
volume = 813,
place = {United States},
year = {Fri Jan 20 00:00:00 EST 2006},
month = {Fri Jan 20 00:00:00 EST 2006}
}
  • No abstract prepared.
  • To improve the performance of Ir-based alloys, the authors propose alloys designed by combining Ir- and Ni-based alloys because Ni-based alloys are ductile, have a relatively low density (about 8.5g/cm{sup 3}, compared to 22g/cm{sup 3} for Ir), and low cost. The objective is to combine the high-temperature strength of Ir-based alloys with the good ductility, low density, and low cost of Ni-based alloys. If the fcc and L1{sub 2} phases with coherent structure form in both alloys, the authors expect that the fcc and L1{sub 2} two-phase regions of the Ir- and Ni-based alloys will connect with each other atmore » the interface of the Ir-based and Ni-based alloys. The coherency of the fcc/L1{sub 2} phase is very important for quaternary alloys to achieve high strength at high temperature. The authors chose the Ir-Ta alloy from the available Ir-based binary alloys because the strength of the Ir-Ta binary alloy is high at high temperature (over 700 MPa at 1,200 C) and because Ta has a solid solution hardening effect in Ni-based alloys. For the Ni alloy, they chose the Ni-Al alloy because it is of coherent structure of fcc and L1{sub 2}. They therefore studied the strength and microstructure of Ir-Ta-Ni-Al quaternary alloys.« less
  • Many attempts have been made in order to improve the temperature capability of Ni-based superalloys by adding more refractory elements into them. In this study, the authors have tried to decrease or eliminate the larger L1{sub 2} phase by adjusting the composition of alloys and find a volume in which only fcc and L1{sub 2} phases exist in quaternary Ir-Nb-Ni-Al. The microstructural evolution and the phase relationships at 1,300 and 1,400 C are investigated, and the coherence between the fcc matrix and the L1{sub 2} precipitates is also discussed.
  • The authors propose a method for developing new quaternary Ir-Nb-Ni-Al refractory superalloys for ultra-high-temperature uses, by mixing two types of binary alloys, Ir-20 at. pct Nb and Ni-16.8 at. pct Al, which contain fcc/L1{sub 2} two-phase coherent structures. For alloys of various Ir-Nb/Ni-Al compositions, the authors analyzed the microstructure and measured the compressive strengths. Phase analysis indicated that three-phase equilibria--fcc, Ir{sub 3}Nb-L1{sub 2}, and Ni{sub 3}Al-L1{sub 2}--existed in Ir-5Nb-62.4Ni-12.6A1(at.pct) (alloy A), Ir-10Nb-41.6Ni-8.4Al(at.pct)(alloy B), and Ir-15Nb-20.8Ni-4.2Al(at.pct)(alloy C) at 1,400 C; at 1,300 C, three phase equilibria--fcc, Ir{sub 3}Nb, and Ni{sub 3}Al--existed in alloys A and C and four-phase equilibria--fcc, Ir{sub 3}Nb,more » Ni{sub 3}Al, and IrAl-B2--existed in alloy B. The fcc/L1{sub 2} coherent structure was examined by using transmission electron microscopy (TEM). At a temperature of 1,200 C, the compressive strength of these quaternary alloys was between 130 and 350 MPa, which was higher than that of commercial Ni-based superalloys, such as MarM247 (50 MPa), and lower than that of Ir-based binary alloys (500 MPa). Compared to Ir-based alloys, the compressive strain of these quaternary alloys was greatly improved. The potential of the quaternary alloys for ultra-high-temperature use is also discussed.« less