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Secondary Processing Development and Prototyping of Cast Single-Piece Vehicle Underbody Structure

Description:

OBJECTIVE: Develop, demonstrate, and prototype a highly scalable secondary process of cast single-piece underbody structures to achieve a combination of high strength and high toughness. DESCRIPTION: The Army is interested in the production of cast steel single-piece underbody structures for combat vehicles. The steel must possess an outstanding combination of strength and toughness for it to survive battlefield threats. With proper heat treatment, Eglin Steel [1,2] can exhibit the required levels of strength and toughness. The challenge here is to develop, demonstrate and prototype a thermal, mechanical, or thermomechanical process (herein referred as a Secondary Process) for very large castings of Eglin Steel, such that the entire structure has the required combination of strength and toughness. The Secondary Process must be able to convert very-large-scale low-alloy steel cast by commercial foundries under the standard foundry casting practices using combination of successive and/or location-specific Secondary Process to sound parts meeting or exceeding the Phase I and II objective as described in following sections without requiring additional capital investments beyond the current SBIR Phase I and Phase II. The selected offerers are expected to be a part of the Army/DoD Science & Technology and ManTech integrated product teams (IPTs); and to work closely with the Army/DoD tiered steel foundries and mills, Army/DoD original equipment manufacturers (OEMs), and Army/DoD tiered supply chain industries to assist the Army/DoD PEO's and PM's Acquisition strategies. PHASE I: Design successive and/or location-specific Secondary Process of as-cast low-alloy steel plates (4 ft wide x 4 ft long x 3 in thick nominal dimension) conforming to the Eglin Steel (ES-1) compositions [1,2] and demonstrate that the designed Secondary Process is able to achieve the Phase I minimum post-cast Secondary Process combination of properties. The Phase I minimum post-cast Secondary Process properties are 180 ksi tensile yield strength, 230 ksi ultimate tensile strength, 12% tensile elongation, and 30 ft-lb Charpy V Notch (CVN) toughness at -40 degrees F [3-5]. Two (2) 4 ft width x 4 ft length x 3 in thickness Secondary Process plates meeting the Phase I minimum post-cast Secondary Process combination of properties shall be produced from one single heat. One (1) of the two (2) identically processed plates shall be destructively evaluated in x, y, and z reference orientations within every 1 ft x 1 ft spacing in the x and y reference orientation at two positions in the z-direction: one at the mid-point of the plate and the other half-way between the mid-point and the surface. These eighteen (18) locations shall be tested to validate the Phase I minimum post-cast Secondary Process combination of properties requirement. The validation test must be done according to the ASTM standards [3-5]. The plate not destructively tested shall be delivered to Army Research Laboratory for blast tests. The Secondary Process design shall be demonstrated to be sufficiently predictable, adaptable, flexible, and robust such that it can be directly integrated into the existing conventional foundry cast manufacturing processes and infrastructures without needing of additional capital investment beyond the SBIR Phase I and Phase II funding. Numerical methodologies in process model and simulation are highly desirable in demonstrating the Phase I Secondary Process predictability. The selected offerers are responsible in either obtaining or casting the ES-1 plates for the Phase I program. PHASE II: The Phase II progam will be to scale up and optimize the Secondary Process of post-cast low alloy steel first, to larger plates, and second, to an entire vehicle underbody tub. Two (2) plates (6 ft wide x 10 ft long x 3 in thick nominal dimensions) with compositions conforming to ES-1 [1,2] shall be processed to achieve the same combinations of properties as Phase I. One (1) of these plates shall be destructively tested to validate the properties and their homogeneity. This plate shall be sampled at every 2 ft in the x-y plane and at the two z positions described under Phase II, giving a total of sixteen (16) positions. The validation testing must be done according to the ASTM standards [3-5]. The plate not destructively tested shall be delivered to the Army Research Laboratory for blast tests. Following successful validation of properties, one (1) full vehicle tub shall be processed. This tub (12 ft wide x 30 ft long x 5 ft high with 2 in to 3 in variable thickness nominal dimension) conforming the ES-1 compositions [1,2] and shall be delivered to Army Research Laboratory for blast tests. The Secondary Process shall be validated to be sufficiently predictable, adaptable, flexible, and robust such that it can be directly integrated into the existing conventional foundry cast manufacturing processes and infrastructures without needing of additional capital investment beyond the SBIR Phase I and Phase II funding. Numerical methodologies in Phase II Secondary Process model and simulation shall be developed, and the model and simulation shall be demonstrated to be highly predictable. The selected offerers are responsible in either obtaining or casting the ES-1 plates for the Phase II. PHASE III: The manufacturing technology shall be transitioned to civil and military sector applications. The manufacturing technology transition to military application includes partnerships with Army/DoD OEMs. Successful Phase II validation facilitates immediate single piece vehicle hull and cap fabrication and integration of demonstrated technology. The manufacturing technology and force protection capability information will be transitioned to both Tank Automotive Research and Development (TARDEC) and Tank Automotive Command (TACOM) for immediate implementation and integration into existing and future platform design and engineering efforts. Deliverables and technical data packages (TDPs) resulting from this SBIR will support a variety of Army PEOs and PMs in Army major acquisition programs. The manufacturing technology to civilian application enable very-large-scale complex-shape cast structural part in ship hulls, transportation vessels, and energy infrastructures where unnecessary joining are critical design requirements. REFERENCES: 1. M. Dilmore and J.D. Ruhlman, Patent No: US 7,537,727 B2, Eglin Steel A Low Alloy High Strength Composition, 26 May 2009. 2. J. Paules, M. Dilmore, and K. Handerhan,"Development of Eglin Steel A New, Ultrahigh-Strength Steel for Armament and Aerospace Applications", Materials Science and Technology Association for Iron and Steel Technology 2005, Vol. 2, page 13-24. 3. ASTM E8/E8M-11 Standard Test Methods for Tension Testing of Metallic Material. 4. ASTM E1820-11 Standard Test Method for Measurement of Fracture Toughness. 5. ASTM E23-07 Standard Test Methods for Notched Bar Impact Testing of Metallic Materials.
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