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Solid State Additive Manufacturing of Titanium Alloys

Description:

TECHNOLOGY AREA(S): Materials/Processes

OBJECTIVE: Develop an additive manufacturing technology capable of processing titanium alloys via solid state joining.

DESCRIPTION: The U.S. Army’s light weighting initiative has resulted in the expanded use of titanium alloys in fielded armament systems. Due to the price of these alloys and their associated machining costs, the titanium components are very expensive to replace. Part refurbishment is a viable option to reduce these types of sustainment costs, and typically relies on the ability to deposit more material on the part in question – perfectly suited for additive manufacturing. However, the major problem with current additive processes is that the technology relies on fusing the new material to the old through melting and solidification. This ultimately leads to a high degree of distortion that usually results in the part falling out of dimensional specification and being rejected anyway. Due to this limitation, a solid state process is desired as the lower heat input will minimize this type of distortion. Additionally, the solid state process is capable of much higher deposition rates. This opens the possibility of expanding the process beyond part refurbishment and into complete near net shape fabrication.

PHASE I: Develop a solid state joining process that is capable of depositing titanium and its alloys for component repair or a near net shape build. The process must have a minimum deposition rate on the order of 20 lb/hour using either powder or wire feedstock. An open air system is preferable but a vacuum dependent system would be acceptable. The process must also have some degree of microstructural control. A process that has the ability for in-situ grain refinement is preferable, but one that limits grain growth is acceptable. All builds shall be subject to extensive characterization and logged in the DARPA Open Manufacturing Additive Process Schema. Deliverables shall be process development documentation in conjunction with materials property data on as deposited material.

PHASE II: Streamline the process developed in Phase I. Particular attention should be given to system automation. At completion of Phase II, the system should require no user input during the build cycle – tooling pathways must be computer controlled. If necessary, a process parameter feedback loop should be implemented to ensure build quality. Deliverables shall be process development documentation, build data logged in the DARPA Open Manufacturing Additive Process Schema, and the prototype system developed under this effort.

PHASE III DUAL USE APPLICATIONS: The material developed under this effort will have a myriad of applications in the military as well as the commercial sector. Of particular interest, component repair and direct part manufacturing are the key areas of interest. Direct part manufacturing would be a true enabling technology as custom tooling would be minimal to nonexistent. This is ideal for applications where a small quantity would be required. Such technology will bring a new level of capability to military as well as commercial consumers. Thus, the ultimate objective is a solid state additive manufacturing process capable of processing titanium and its alloys so as to maximize performance while minimizing the distortion traditionally associated with these types of repair.

REFERENCES:

    • W.M. Thomas, I.M. Norris, D.G. Staines, E.R. Watts, “Friction stir welding – process development and variant techniques,” Proc. SME Summit, Milwaukee, WI, USA, August 2005.

 

    • I. Bhamji, M. Preuss, P.L. Threadgill, A.C. Addison, “Solid state joining of metals by linear friction welding: A literature review,” Materials Science & Technology 2010, Vol. 27, No. 1, January 2011, pp. 2-12.

 

    • H. Kreye, “Melting Phenomena in Solid State Welding Processes,” AWS Welding Research Supplement, May 1977, pp. 154-s – 158-s.

 

  • E. Brandl, A. Schoberth, C. Leyens, “Morphology, microstructure, and hardness of titanium (Ti-6Al-4V) blocks deposited by wire-feed additive layer manufacturing (ALM),” Materials Science and Engineering: A, Vol. 532, January 2012, pp. 295-307.

KEYWORDS: additive manufacturing, titanium, joining, repair, refurbishment, solid state

  • TPOC-1: Jeffrey Schutz
  • Phone: 973-724-5333
  • Email: jeffrey.r.schutz.civ@mail.mil
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