SBIR-STTR Award

Warhead liner performance is greatly affected by three liner material properties, namely, strength, ductility and circumferential symmetry. Extensive work done in the area of on-axis upset forging of round bar stock to form liner plates has demonstrated symmetry of texture which is necessary for uniform geometry during explosive formation. Additional development has focused on severe plastic deformation, using the technique of equal channel angular pressing (ECAP) of the starting bar stock, to condition the material prior to upset forging and to eliminate microstructure variations from multiple material vendors. Recent work in the rolling of copper plate at cryogenic temperatures, followed by a rapid anneal, has been found to create a duplex grain structure that produces high levels of strength and ductility simultaneously. The extension of the cryogenic temperature environment to ECAP processing, offers the possibility of warhead liners with an unprecedented combination of ductility and strength, which would provide enhancements in penetrator length and penetration depth respectively. In addition, the use of upset forging following cryogenic ECAP will generate the texture symmetry needed for uniform geometry during explosive forming. Such characteristics would offer the warhead designer the best possible material performance for a variety of applications

Warhead liner performance is greatly affected by three liner material properties, namely, strength, ductility and circumferential symmetry. Extensive work done in the area of on-axis upset forging of round bar stock to form liner plates has demonstrated symmetry of texture which is necessary for uniform geometry during explosive formation. Grain refinement of the material has been achieved through pre-processing of the blank with equal channel angular pressing (ECAP). Work done in Phase I has shown that cryogenic ECAP, performed at -195?C, followed by a controlled annealing process, can produce dramatic enhancements in both strength and ductility of copper. Increases in these material properties can provide performance increases in warhead liner penetration capability. Phase II work will scale up this technology to the production of 9-inch diameter plates for liner testing. In addition, shaped charges from cryogenically ECAP processed material will be test fired in direct comparison with production Javelin parts. Through this Phase II project, both the strength and ductility of copper warhead liners would be significantly increased, leading to greater performance in a number of warhead applications

Keywords:
Warhead, Liner, Severe Plastic Deformation, Cryogenics, Strength, Ductility, Copper, Ecap