N102-106 TITLE: High Strength Stress Corrosion Resistant Aluminum Casting Alloys

TECHNOLOGY AREAS: Ground/Sea Vehicles, Materials/Processes

ACQUISITION PROGRAM: PM Advanced Amphibious Assault - ACAT I

OBJECTIVE: Develop castable and weldable high strength stress corrosion resistant aluminum alloys for the production of structural cast components.

DESCRIPTION: The United States Marine Corps (USMC) is pursuing high-performance aluminum castings for components, such as the steering bucket and the waterjet inlet housing, of the Expeditionary Fighting Vehicle (EFV). Aluminum alloy A206 is one alloy that has been used. This alloy is susceptible to hot tearing during casting and has inferior stress-corrosion cracking resistance. There is a need for a design-for-castability effort to develop mechanistic material models. These models will enable computational alloy design within this system, including a custom thermodynamic database; precipitation models coupled with strength models; solidification simulations to address innoculation, hot-tearing, and homogenization issues; and qualitative models of stress-corrosion cracking (SCC). Using the modeling approach, the SBIR contractor shall develop and produce castable and weldable high-strength stress-corrosion resistant aluminum alloys for the production of structural cast components, such as the EFV water jet inlet housing or steering bucket. The target component of this SBIR project shall be determined at the Kick Off meeting, but the waterjet inlet housing is a higher priority if cost constraints accommodate this choice. The developed alloy strength, fatigue, and stress corrosion properties must meet or exceed the A206 Aluminum Alloy properties. The developed alloy must also be castable, with no hot cracking or hot shortness propensity and must be weldable.

PHASE I: The contractor shall conduct modeling to investigate the chemistry, thermodynamics, and heat treatments to develop castable and weldable high-strength, stress-corrosion resistant aluminum alloys with superior hot cracking resistance, that can be used to produce large structural components. The contractor shall plan and carry out testing to assist in the down selection of the chemistry and the alloys that could be carried into the Phase II effort. The Contractor shall conduct a Kick-off and a Final Review meeting at the Program Office.

PHASE II: In the Phase II effort, the contractor shall down select the chemistry with further testing to insure meeting the required strength and stress corrosion resistance properties, as well as the castability and weldability. The contractor shall produce prototype test components to evaluate castability and weldability. Based on the results, the contractor shall scale up his efforts to produce components, such as the waterjet inlet housing or the steering bucket, with waterjet inlet housing as the priority item. The contractor shall produce prototype components by casting. Various tests, including mechanical, corrosion, and welding shall be performed. Based on the results, the contractor shall produce additional castings of the components, and these castings shall be machined, painted, and delivered for on-vehicle testing by the government. The Contractor shall conduct a Kick-off, three semi-annual reviews, and a Final Review meeting at the Program Office.

PHASE III: Transition technology into EFV for Low Rate Initial Production.

PRIVATE SECTOR COMMERCIAL POTENTIAL/DUAL-USE APPLICATIONS: The cast high strength aluminum alloy and the casting technology should enable many platforms to utilize this alloy and approach for several major military land and aircraft programs. This alloy would find extensive application in the automotive industry, as the comparative alloy A206 is a commercial alloy used in the automobile industry, as well as in the commercial aircraft industry.

REFERENCES:
1. PM AAA Website - www.efv.usmc.mil

2. SAE AMS 4235

KEYWORDS: High Strength Aluminum Alloys; Castable; Weldable; Stress Corrosion Resistant; A 206 aluminum alloy; Inlet Housing; Steering Bucket

** TOPIC AUTHOR (TPOC) **

DoD Notice:   Between April 21 and May 19, 2010, you may talk directly with the Topic Authors to ask technical questions about the topics. For reasons of competitive fairness, direct communication between proposers and topic authors is not allowed starting May 19, 2010, when DoD begins accepting proposals for this solicitation.

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