Enhanced Lower Cost Tooling for Friction Stir Technologies
AREA(S): Air Platform, Ground/Sea Vehicles, Materials/Processes
PROGRAM: Program Executive Office – Land Systems (ACAT I vehicle programs)
This project will develop new material processing routes and technologies
toward high-toughness, super-hard cubic boron nitride-based materials for use
in friction stir welding (FSW) tool applications.
FSW is a solid-state joining process that uses a third body tool to join two
mating surfaces. Heat is generated between the tool and material, which
softens material to allow material mixing. Currently, it is primarily used on
aluminum structures that need superior weld strength without a post-weld heat
treatment. The Navy and Marine Corps have interest in developing tools for use
in the joining and repair of high hardness steel and other hard materials that
involve higher temperatures and fracture toughness than aluminum FSW; this will
require the development of new, low-cost tool materials with longer lifetimes.
The proposed research will advance the current state-of-the-art of FSW tool
materials. The key aspects of the study will be: A) material selection
utilizing theory/computational modeling to evaluate tool material
compatibility; B) fabrication of material coupons; C) mechanical evaluation of
test coupons; and D) fabrication and evaluation of friction stir welding
tools. The project will develop new bulk material or novel processing
techniques for material fabrication. This research has the potential to
improve the efficiency of current FSW tool technology by developing lower cost
processing techniques or identifying new compositions that lead to less
expensive, longer lasting tools.
Current tool materials for FSW processing of steel are based primarily on cubic
boron nitride (cBN). These materials are difficult to process to full density
due to the highly covalent nature of the bonding and the sensitivity of the
reversible phase transformation at higher processing temperatures. Metallic bond
phases have been utilized to make dense multiphase “cermet “compositions that
provide a tough, bond matrix phase (metal) with super-hard cBN particulate.
Previous studies have shown that smaller amounts of the bonding phase result in
tool materials that have high hardness, but suffer from poor thermal stress
response. They demonstrate poor thermal cycling response, and typically fail
in the initial plunge or during the extraction of the tool in the friction stir
process. Transient thermal loads drive the through-thickness stresses causing
the tool to fail from poor strain response. The addition of a more ductile
bond phase alleviates this failure mode, but drives a more rapid wear response
of the tool, again leading to shortened tool lifetimes. Expensive refractory
metals are currently used to provide tools with longer life, but that expense
limits the commercial viability of FSW for more widespread industrial use.
I: Define and develop a concept/approach using computational tools for a
new/optimized tool material composition, or novel processing technique to
produce bulk materials of current compositions. It is intended that the focus
of the program be to target materials by understanding the thermochemistry of
tool material in its use environment. This includes investigating if the bond
phase reacts with harder phases that may negatively impact tool performance at
the use temperature of 1,000°C and exploring if the tool material reacts with
the steel at those temperatures to negatively impact the as-fabricated weld
properties. Computationally guided materials selection to define the
composition space will be of high importance.
The mechanical and thermal properties (modulus, fracture toughness, strength,
coefficient of thermal expansion, and thermal conductivity) properties of the
candidate tool materials (at room temperature (RT) and use temperature) can
cover a wide range and there are tradeoffs for these tool properties. However,
as the Navy and Marine Corps desire improved tool life at lower cost, some
properties of commercially available tool materials are listed as a reference.
To ensure progress in the Phase I plan, a key deliverable will be a sample
material coupon (0.25” diagonal x 0.5” high) for independent Government testing
and report of achieved material properties, with requisite documentation
showing the rationale for selection (computational thermodynamics) and the
description of the processing technology used to process the material.
Develop a Phase II plan.
II: Based on Phase I results, develop, demonstrate, and validate the proposed
computational approach for new/optimized materials and/or processes. This will
include demonstrating optimized material composition(s) in large test builds in
order to measure mechanical and thermal properties (at RT and elevated
temperatures), and to characterize the microstructure and composition (grain
size, porosity, phase identification/quantification).
Begin initial FSW studies in order to determine viability of the material for
compatibility with the thermal and mechanical loads placed on the tool during
use, as well as potential chemical interaction with the steel weldment. It is
recommended that the performer initiate work with experts in commercial FSW
processing, as well as joining/repair OEMs to facilitate transition into Phase
Phase II will necessitate scale up of the process in order to produce larger
size billets/blanks for thermal and mechanical property characterization as
well as for extraction of sample tool shapes for initial FSW studies. A Phase
II option would involve supplying a government laboratory or FSW partner with
the small tool shapes for plunge and extraction tests on steel (minimum 1”
diagonal x 1” high).
III DUAL USE APPLICATIONS: Phase III will produce full-size FSW tools made from
materials and processes developed under the program performing at equivalent
speeds, feed rates, and test boundary conditions set forth during the program
by the Navy (equivalent to or better than state-of-the-art tool materials
performance) to industry partners or Navy Warfare Centers/DoD
production/maintenance facilities. Phase III will also plan to transition
optimized materials compositions and/or processes to commercial suppliers
through partnering agreement with OEMs, repair depots, etc. FSW can be used in
manufacturing and repairs of very hard materials in commercial industries as
Rai, R., De, A., Bhadeshia, H. K. D. H., and DebRoy, T. “Review: friction stir
welding tools.” Science and Technology of Welding and Joining. 16, 325-342. http://www.tandfonline.com/doi/abs/10.1179/1362171811Y.0000000023
Dialami, N., Chiumenti, M., Cervera, M., and Agelet de Saracibar, C.
“Challenges in Thermo-mechanical Analysis of Friction Stir Welding Processes.”
Archives of Computational Methods in Engineering: State of the Art Reviews.
2017. 24, 189-225. https://link.springer.com/article/10.1007/s11831-015-9163-y
Hanke, S., Lemos, G., Bergmann, L., Martinazzi, D., Dos Santos, J., and
Strohaecker, T. “Degradation mechanisms of pcBN tool material during Friction
Stir Welding of Ni-base alloy 625. Wear, 2017. 376-377, 403-408. http://www.sciencedirect.com/science/article/pii/S0043164817301898
Sorensen, CD. “Progress in Friction Stir Welding High Temperature Materials.”
Brigham Young University. http://fsrl.byu.edu/presentations/Progress%20in%20Friction%20Stir%20Welding.pdf
Friction Stir Welding; FSW
** TOPIC NOTICE **
These Navy Topics are part of the overall DoD 2018.A STTR BAA. The DoD issued its 2018.A BAA SBIR pre-release on November 29, 2017, which opens to receive proposals on January 8, 2018, and closes February 7, 2018 at 8:00 PM ET.
Between November 29, 2017 and January 7, 2018 you may talk directly with the Topic Authors (TPOC) to ask technical questions about the topics. During these dates, their contact information is listed above. For reasons of competitive fairness, direct communication between proposers and topic authors is not allowed starting January 8, 2018 when DoD begins accepting proposals for this BAA.
However, until January 24, 2018, proposers may still submit written questions about solicitation topics through the DoD's SBIR/STTR Interactive Topic Information System (SITIS), in which the questioner and respondent remain anonymous and all questions and answers are posted electronically for general viewing until the solicitation closes. All proposers are advised to monitor SITIS during the Open BAA period for questions and answers and other significant information relevant to their SBIR/STTR topics of interest.
Topics Search Engine: Visit the DoD Topic Search Tool at sbir.defensebusiness.org/topics/ to find topics by keyword across all DoD Components participating in this BAA.
Proposal Submission: All SBIR/STTR Proposals must be submitted electronically through the DoD SBIR/STTR Electronic Submission Website, as described in the Proposal Preparation and Submission of Proposal sections of the program Announcement.
Help: If you have general questions about DoD SBIR program, please contact the DoD SBIR/STTR Help Desk at 800-348-0787 or via email at firstname.lastname@example.org